Chapter 18 in my ongoing quest to meanderingly pedanticize the world.
I've been brooding over the nature of creativity since I noticed a disconnect between two different broad usages of the word. If I say Bob is creative, I can mean that he:
1. creates things.
or
2. is imaginative.
The first, I imagine, is closer to the roots of the word, but the second is much more common. If I tell you that I know a guy named Bob and that he's very creative, you would probably imagine somebody with unique style, an artist's flair for the new and different, and a certain unrealistic and colorful view on life. At least that's the image I get.
The interesting thing is that being creative in this way doesn't say anything about one's actual creation of anything. Engineers--not everyone's creative archetype--create things all the time, but colorful creative personalities might actually create nothing. I'm not arguing that this is in any way wrong--language can make whatever it wants out of the words we use--but the distinction is interesting because it shows how much we culturally evaluate creativity as an attitude or personality and not as a process of creation.
I came upon this disconnect while trying to label myself [a fantastic waste of time]. I have always felt a profound motivation to make things--music, photographs, drawings, snowflakes, model rockets, electronics, dams, forts, holes, gardens, websites, food, books, songs, code, solutions, essays, babies. But calling that "creativity" implies a lot of things which--regardless of whether they are true or not--have nothing to do with this creative impulse. So, I want a way to think of these two ideas--creation and imagination--independently.
I imagine there is a continuum of possible "amounts" of each of these two types of creativity which each person has. And I doubt they're correlated. And no doubt a large portion of the world's more successful artists, scientists, architects, musicians, chefs, engineers, lawyers, contractors, entrepreneurs, and criminals have decent amounts of both. I can't think of many situations where creativity wouldn't help performance, and it is basically a uniformly recognized [but soft] virtue.
Synthesizing these two ideas, we get creativity as a process of imagination motivating creation. This is probably what I would like the word creativity to express. Take, for example, the three processes of creation that I've noticed in my own life and by observation, with Bob as proxy. These represent the three general paths whereby a new thing can come into existence.
1. Inspiration lands in Bob's head. He follows it.
2. Bob has some good ideas. He uses talent, work, and time to stitch them together into something.
3. Bob sits down with no ideas but with a goal to make something. He forces it into existence with no particular inspiration, using only his skills and concerted effort.
It would be fair to say that, in a sense, the first path is the "higher" path. But there's nothing in essence wrong with the third approach--it just seems less likely to produce remarkable results. In fact, I imagine that the bulk of the creation that is done is of the third type; crank the stuff out because somebody will buy it, instead of sell it because it's worth buying. This Dell PC that I'm typing on right now is a result of that approach, so I shouldn't complain too loudly. That being said, the third path is less creative [by my definition].
Anybody who has made an effort to create has probably experienced each of these three states. You can't control inspiration [whatever that is] so if you're regularly driven to create something you'll use the third method at least some of the time. Brahms did--he threw away huge amounts of music that he didn't feel met his standards, a fact which many musicians bemoan but I am grateful for. So it's nothing to be ashamed of--unless your entire career is the mass production of forced-into-existence soulless pieces of corporate detritus. Then you should be ashamed [but you wouldn't have lasted this far into this post if that was you].
And what about the crucial element of creativity, uniqueness? It's essential to any of these three steps. If it's not original, it's not creation you're doing, it's mimicry. And don't get me wrong, mimicry has its place too--every band has its own sound [Beatles respectfully excepted]. But even to accomplish creation of the third kind requires something new. I like to remind myself often though that uniqueness is not a measure of creativity any more than sheer bulk of output is. Anybody can do something that has never been done before--I just picked my ear with a bottle of contact solution, balanced my salsa bowl on my cup and then blogged about it--but that doesn't mean it's an expression of creativity. I feel that this is the major trap that people fall into when they run out of inspiration: they replace it with idea-free experimentation [see: Wild Honey Pie].
There is no conclusion. But I feel like I understand creativity better--perhaps not in the cognitive sense but in the psychological sense. The best summation I can make is this:
Creativity is imagination which motivates creation. The more inspiration is involved the better the result. Creativity motivates experimentation and creates unique results, but does not come from them.
Monday, December 22, 2008
Tuesday, November 4, 2008
Monday, October 6, 2008
Killing in the name of
[by mandamommy and trogonpete]
From our perspective, there are two distinct questions pertaining to the Iraq war that are often lumped together. The first is whether we were right to invade in the first place. The second question is what we do now that we’re in. We believe that the first question needs to be answered first, because it necessarily motivates the answer to the second question.
Invasion:
The original justification for invading Iraq is often cited this way: Iraq seemed to be producing weapons of mass destruction. The theory was that part of our war on terrorism included pre-emptive strikes against terrorists likely to attack the US.
But the actual original justification predated 9/11 and had nothing to do with terrorism. The neoconservative group Project for a New American Century [PNAC] sent a letter in 1998 to President Clinton urging a strategy aimed at “the removal of Saddam Hussein’s regime from power.” The group believed in the establishing of an “American empire” and proposed that American dominance in the 21st century should be maintained by "fight[ing] and decisively win[ning] multiple, simultaneous major theater wars." The main goal of the group was to convince the government to invade Iraq.
So who is the PNAC? Well, you might have heard of Dick Cheney. And Donald Rumsfeld. And 15 other well-known names later part of the Bush administration. Nearly everybody advising Bush after 9/11 were members of the PNAC, a group that had a clear and public agenda of bringing war to Iraq for the purpose of maintaining American “hegemony.” These are the very same people who attempted to discredit the entire CIA after the intelligence agency proved that there was no WMD threat from Iraq.
10 days after George Bush took office he instructed his staff to begin drawing up plans for an invasion of Iraq.
Additionally, it is now well documented that Bush, Cheney and Rumsfeld lied about the WMD’s and misled the American people about Iraq being part of the war on terror. There were no WMD’s, and the administration knew it. Again, this much is well documented [along with almost 1000 other lies told between 2001 and 2003 by the Bush administration about the threat Iraq posed to the US, according to the Center for Public Integrity].
As far as the war on terror was concerned, bin Laden and Saddam were enemies; Saddam represented the secular Islamic ideal so repugnant to fundamentalists like bin Laden, and Saddam considered bin Laden a—well, terrorist. Additionally, there never was any possibility that Saddam was in the terrorism business—he was a cruel dictator, but he wasn’t interested in flying planes into American buildings.
But the administration said Saddam had WMD’s and that these WMD’s could be used as weapons of terror on American soil. Donald Rumsfeld, as the Secretary of Defense, made it clear that what was at stake in Iraq was the potential for Saddam to repeat 9/11 but on a much larger scale. Again, this is a deliberate lie; Saddam never had any connection to al Qaeda and had no interest in terror operations in the US.
So we invaded Iraq.
The interesting footnote here is that many supporters of the war now cite how bad Saddam was and what a service we have done to the world in getting rid of him. But what about Robert Mugabe? What about Kim Jong-il? Than Shwe? Hu Jintau? Sayyid Ali Khamenei? And there’s no way Saddam was worse than Omar al-Bashir. Should we invade Zimbabwe, North Korea, Myanmar, China, Iran and Sudan in order to depose tyrants? Is that our role? If so, why aren’t we doing it?
We believe—as members of the Church of Jesus Christ of Latter-day Saints—that we should “renounce war and proclaim peace.” [D&C 98:16] War is justifiable only in cases when it is necessary to defend our families [Alma 43:47] and plausibly our rights and freedoms [akin to Alma 48:10]. War is also a purely defensive means of preservation [Alma 48:14] and even pre-emptive war is expressly forbidden, even in cases where a pre-emptive strike would prevent a terrorist attack [3 Nephi 3:20-21]. Modern scriptures clearly forbid the invasion of Iraq and the prophesies concerning the failure of offensive endeavors are applicable.
[Each of these scriptures pertains to a situation analogous to the position we were in; the saints in Missouri wanted to take the fight to their persecutors and the Lord forbad it, the Nephites wanted to pre-emptively attack the terrorist Gadianton robbers but were forbidden. We believe that the inclusion of these councils in the scriptures is very strong council for us and pertains to our government as well.]
This is an unjust war, founded on a thousand lies and violating basic morality.
The immorality of the invasion is key to the discussion about what we do now:
A much more complicated question is what we should do now that we’re in Iraq. It is very important at this time to step back and admit that nobody—nobody anywhere—has any idea what the future holds. The military experts told us the war would be quick, painless and easy. They were wrong. The civilian experts said the surge would only exacerbate the violence. They were wrong. So any time a politician says something like “setting a timetable will plunge Iraq into a civil war” or “the fighting will never continue as long as we’re there,” we shouldn’t believe it for a second. The truth is that nobody knows and even the best analysis is a guess.
Politicians also like to talk about “winning” and “losing” the war. This is pure propaganda. It is meaningless. In a sense, we have already lost: we lost over 4,000 American soldiers—significantly more than the number of civilians lost in 9/11—we lost our moral standing in the world, we lost trillions of dollars, we lost the opportunity to capture or kill the terrorists responsible for 9/11, we lost trust in our government, and our government lost the trust of the world. We lost our national integrity. We created a country full of destitute anti-American terrorists where once there was a country of poor repressed farmers. A million Iraqis lost their lives. Every day we stay we lose more. The only metric of victory in a war like this one is preventing further losses.
This is where the immorality of the invasion comes to play. Having losses does not imply a war is lost. World War II was a victory in the sense that Hitler’s ambition at global domination was ended, and Americans had to pay dearly. But when the cause that these troops are fighting for is an ignorant, arrogant global domination scheme dreamed up by a few radical ideologues in the government, when “dying in vain” becomes propaganda for dying for oil and power, when planning to save American lives is branded “unpatriotic” and “defeat,” then we have lost. But neither Saddam Hussein nor Osama bin Laden beat us. We just lost.
Still, it would be clearly irresponsible of America to just pack up and leave. The infrastructure needs to be rebuilt. We need to make sure the Iraqi army is competent enough to prevent a plunge into anarchy. That’s why we need to stay. But we must stop the bleeding as soon as possible. This means setting a firm goal with the government of Iraq after which they will be on their own, then get out. Every day we spend there the more we lose. An open-ended policy seems foolish; with our tax dollars flowing into the country, what great motivation does the government of Iraq have to pick up the slack themselves? With no carrot and no stick, the donkey ain’t moving.
Of course we’re not experts. We know very little and understand less. But we do know that the invasion was wrong. And that fact alone compels us to want out—the best way to repent, we believe, is to stop sinning. That’s a good first step.
Friday, September 26, 2008
Deceit and ... Silliness
For anybody who may have doubted that Palin really buys the McCain campaign's garbage about the proximity of Russia to Alaska giving her foreign policy experience, there's this:
COURIC: You've cited Alaska's proximity to Russia as part of your foreign policy experience. What did you mean by that?
PALIN: That Alaska has a very narrow maritime border between a foreign country, Russia, and on our other side, the land-- boundary that we have with-- Canada. It-- it's funny that a comment like that was-- kind of made to-- cari-- I don't know, you know? Reporters--
COURIC: Mock?
PALIN: Yeah, mocked, I guess that's the word, yeah.
COURIC: Explain to me why that enhances your foreign policy credentials.
PALIN: Well, it certainly does because our-- our next door neighbors are foreign countries. They're in the state that I am the executive of. And there in Russia--
COURIC: Have you ever been involved with any negotiations, for example, with the Russians?
PALIN: We have trade missions back and forth. We-- we do-- it's very important when you consider even national security issues with Russia as Putin rears his head and comes into the air space of the United States of America, where-- where do they go? It's Alaska. It's just right over the border. It is-- from Alaska that we send those out to make sure that an eye is being kept on this very powerful nation, Russia, because they are right there. They are right next to-- to our state.
By those qualifications, the governer of Missouri has foreign policy experience because the B2's used to bomb Iraq in 2003 flew out of an air base there. Again, she's claiming experience from what the military is doing in Alaska; it has nothing to do with her.
Read that carefully a couple times. It's disturbing.
COURIC: You've cited Alaska's proximity to Russia as part of your foreign policy experience. What did you mean by that?
PALIN: That Alaska has a very narrow maritime border between a foreign country, Russia, and on our other side, the land-- boundary that we have with-- Canada. It-- it's funny that a comment like that was-- kind of made to-- cari-- I don't know, you know? Reporters--
COURIC: Mock?
PALIN: Yeah, mocked, I guess that's the word, yeah.
COURIC: Explain to me why that enhances your foreign policy credentials.
PALIN: Well, it certainly does because our-- our next door neighbors are foreign countries. They're in the state that I am the executive of. And there in Russia--
COURIC: Have you ever been involved with any negotiations, for example, with the Russians?
PALIN: We have trade missions back and forth. We-- we do-- it's very important when you consider even national security issues with Russia as Putin rears his head and comes into the air space of the United States of America, where-- where do they go? It's Alaska. It's just right over the border. It is-- from Alaska that we send those out to make sure that an eye is being kept on this very powerful nation, Russia, because they are right there. They are right next to-- to our state.
By those qualifications, the governer of Missouri has foreign policy experience because the B2's used to bomb Iraq in 2003 flew out of an air base there. Again, she's claiming experience from what the military is doing in Alaska; it has nothing to do with her.
Read that carefully a couple times. It's disturbing.
Thursday, September 18, 2008
Deceit and Outrage
Guy walks into a job interview. Interviewer asks if he feels he's sufficiently educated for the job.
GUY: "Well, I grew up in Oakland. Berkeley and Oakland are neighbors."
INTERVIEWER: "What knowledge did you obtain due to your proximity to Berkeley?"
GUY: "Oakland and Berkeley are neighbors, and there's even a hill in Oakland you can climb and actually see the Berkeley tower."
INTERVIEWER: "What knowledge does that give you?"
GUY: "Well, it means it's a small world."
Does he get the job? Of course not. Even if the job required no special schooling, the sheer audacity of the bald deceit involved in Guy's claim to education would disqualify him from any job in the eyes of a self-respecting interviewer. It's downright offensive. If Guy expected the interviewer to buy that, what does he think of the interviewer's intelligence? And can the interviewer expect him to be an honest employee?
Here's another story, even more ludicrous, you may have heard this one:
SARAH PALIN: "...And, Charlie, you're in Alaska. We have that very narrow maritime border between the United States, and the 49th state, Alaska, and Russia. They are our next door neighbors.We need to have a good relationship with them. They're very, very important to us and they are our next door neighbor."
CHARLES GIBSON, ABC NEWS: "What insight into Russian actions, particularly in the last couple of weeks, does the proximity of the state give you?"
PALIN: "They're our next door neighbors and you can actually see Russia from land here in Alaska, from an island in Alaska."
GIBSON: "What insight does that give you into what they're doing in Georgia?"
PALIN: "Well, I'm giving you that perspective of how small our world is and how important it is that we work with our allies to keep good relation with all of these countries, especially Russia..."
Before you rush in and claim that these two stories are not perfectly analogous, let me say that you're right. Palin is much much worse than Guy. There is a decent probability that Guy, growing up in Oakland, benefited from some small cultural trickle-down from the [relatively] nearby university. It is even likely that Guy has been to Berkeley. But Palin has never seen Russia, she's never been there, she's never interacted with diplomats from there, she's never dealt with Russian-American common interests in the region, there is no Russian foreign policy trickle-down floating across the Bering Strait, and she surely hasn't picked up any clues to Russian motivations for the invasion of a small democracy 5,000 miles away. Guy was just trying to deceive the interviewer to get a job. Palin? The entire country.
Before I analyze her comments further, let me make one thing clear: I'm not currently interested in the question of whether Sarah Palin is qualified to be VP. What interests me is the culture of deceit in the McCain-Palin campaign that this story symbolizes. The campaign and even John McCain himself have repeated this exact same argument on national TV. This is not a poor choice of words by a candidate under duress; it is apparently a coordinated talking point within the campaign designed to convince voters that Palin is experienced enough in foreign affairs to be VP and, by extension, P. Yet it would be safe to claim that both Palin and McCain understand the deceit inherent in this claim; Palin certainly understands that she never interacted with Russia in any way as Governor of Alaska. But she apparently has no qualms feeding this story to the public. America hasn't seen somebody this comfortable deceiving us since... well, Dick Cheney and Karl Rove.
GUY: "Well, I grew up in Oakland. Berkeley and Oakland are neighbors."
INTERVIEWER: "What knowledge did you obtain due to your proximity to Berkeley?"
GUY: "Oakland and Berkeley are neighbors, and there's even a hill in Oakland you can climb and actually see the Berkeley tower."
INTERVIEWER: "What knowledge does that give you?"
GUY: "Well, it means it's a small world."
Does he get the job? Of course not. Even if the job required no special schooling, the sheer audacity of the bald deceit involved in Guy's claim to education would disqualify him from any job in the eyes of a self-respecting interviewer. It's downright offensive. If Guy expected the interviewer to buy that, what does he think of the interviewer's intelligence? And can the interviewer expect him to be an honest employee?
Here's another story, even more ludicrous, you may have heard this one:
SARAH PALIN: "...And, Charlie, you're in Alaska. We have that very narrow maritime border between the United States, and the 49th state, Alaska, and Russia. They are our next door neighbors.We need to have a good relationship with them. They're very, very important to us and they are our next door neighbor."
CHARLES GIBSON, ABC NEWS: "What insight into Russian actions, particularly in the last couple of weeks, does the proximity of the state give you?"
PALIN: "They're our next door neighbors and you can actually see Russia from land here in Alaska, from an island in Alaska."
GIBSON: "What insight does that give you into what they're doing in Georgia?"
PALIN: "Well, I'm giving you that perspective of how small our world is and how important it is that we work with our allies to keep good relation with all of these countries, especially Russia..."
Before you rush in and claim that these two stories are not perfectly analogous, let me say that you're right. Palin is much much worse than Guy. There is a decent probability that Guy, growing up in Oakland, benefited from some small cultural trickle-down from the [relatively] nearby university. It is even likely that Guy has been to Berkeley. But Palin has never seen Russia, she's never been there, she's never interacted with diplomats from there, she's never dealt with Russian-American common interests in the region, there is no Russian foreign policy trickle-down floating across the Bering Strait, and she surely hasn't picked up any clues to Russian motivations for the invasion of a small democracy 5,000 miles away. Guy was just trying to deceive the interviewer to get a job. Palin? The entire country.
Before I analyze her comments further, let me make one thing clear: I'm not currently interested in the question of whether Sarah Palin is qualified to be VP. What interests me is the culture of deceit in the McCain-Palin campaign that this story symbolizes. The campaign and even John McCain himself have repeated this exact same argument on national TV. This is not a poor choice of words by a candidate under duress; it is apparently a coordinated talking point within the campaign designed to convince voters that Palin is experienced enough in foreign affairs to be VP and, by extension, P. Yet it would be safe to claim that both Palin and McCain understand the deceit inherent in this claim; Palin certainly understands that she never interacted with Russia in any way as Governor of Alaska. But she apparently has no qualms feeding this story to the public. America hasn't seen somebody this comfortable deceiving us since... well, Dick Cheney and Karl Rove.
Let me be again be clear: I'm not accusing Palin of lying. I'm [re-]documenting her deceit. Let's analyze her claims in detail:
Start in Sarah Palin's hometown of Wasilla. Drive to Anchorage and board a plane. Fly 500 miles over completely uninhabited wilderness to the town of Nome on the remote western coast of Alaska. Hire [at great cost] a helicopter to fly 120 miles to Little Diomede, a small island in the middle of the Bering Strait. This is the only way to get to Little Diomede; it has no port and no airport, the population of about 170 Inupiat Eskimos isolated from the rest of the world but for a weekly mail helicopter and a single cargo barge each year. If you're lucky and the weather is good, you can now look west and see another island on the horizon. This is Big Diomede which, for historical technicalities, is actually part of Russia. Big Diomede has a permanent population of exactly zero. Beyond Big Diomede, over the Bering Sea, lies the Chukotka Autonomous region of Russia, with a population density of 0.18 per square mile; less than 1/6th that of Alaska, which is by far the least densely populated state in the country [Wyoming, the next lowest, has 5.4 citizens per square mile]. Chukotka is so remote that its large oil reserves and other resources are largely untapped. See this map: Alaska on the right, Little Diomede and Big Diomede in the middle, with Chukotka on the left.
Furthermore, Russia is so big that Wasilla is barely further from the business end of the country--Moscow--than Boston is, via a Great Circle route. You don't hear Mitt Romney touting his foreign policy experience because he was the governor of a state only 4,500 miles away from Moscow. In fact, to fly to Moscow from Anchorage requires flying down to the lower 48 and flying east over Europe. So Wasilla--in practical terms--is as far from the heart of Russia as any place you can find in the Northern Hemisphere.
The point is this: While it is technically true that it's possible to see part of Russia from an island in Alaska, this fact is irrelevant to Palin's foreign policy experience in the following ways:
1. Sarah Palin has neither seen Russia nor traveled to Russia
2. The region of Russia adjacent to Alaska has negligible strategic importance
3. Palin has never met with official Russian delegations
4. Alaska is functionally further from the Kremlin than almost anywhere else in the Northern Hemisphere.
Unless foreign policy experience is acquired through some kind of bizarre geographically selective osmosis, Palin can claim exactly none due to her home state's proximity to Russia.
Some cite the fact that Palin was commander of the Alaska National Guard. Well, this is true, but any time National Guard troops are used for international issues they are federalized under command of national military leaders. The frequently-cited Alaskan National Guard troops in Iraq are not commanded by Sarah Palin. Executive experience [whatever that means, and why it's suddenly the only kind of applicable experience, is another question entirely] maybe, but foreign policy experience? Hardly.
Let me get back to the point. This little deceit is a microcosm of the McCain-Palin campaign. They have shown an epic degree of comfort with deceiving the American public for political gain. Sarah Palin and John McCain both know that there is exactly zero substance behind the some-Alaskans-can-see-a-remote-part-of-uninhabited-Russia-sometimes-and-therefore-the-Alaskan-Governer-is-experienced-in-foreign-affairs claim. When they use this argument, they are consciously trying to deceive the country. That is terrifying to me, as an American citizen. And, truth is, this isn't even close to the most egregious example of McCain-Palin deceit. Check any one of the non-partisan fact-checking sites like FactCheck.org and PolitiFact.com. It's shocking: full-up straight-faced pants-on-fire lies.
Having foreign policy experience with Russia may or may not be a legitimate mandatory qualification for VP candidates; I haven't argued either way. But the willful, persistent, coordinated deceit that the McCain-Palin campaign is willing to feed the American people signals a moral corruption and deep cynicism that profanes the offices they are running for. This isn't politics as usual, this is the politics of change: change from fibs, exaggerations and disinformation to dirty, filthy, brazen lies.
Monday, September 8, 2008
Thursday, June 19, 2008
Montebello
I backpacked solo in Montebello friday and saturday. The lighting was unreal due to a nearby fire. Here are a few of the several hundred pictures I took on friday. I hope you like California grass. Enjoy.
At about 5pm a large cloud of smoke covered the sun.
Count my aperture blades.
As the smoke patch cleared the normal gorgeous colors came out briefly.
One of the sweat-sucking little buggers.
I think this is a white butterfly mariposa lily.
Bees were mobbing the soap plants.
At about 5pm a large cloud of smoke covered the sun.
Count my aperture blades.
As the smoke patch cleared the normal gorgeous colors came out briefly.
One of the sweat-sucking little buggers.
I think this is a white butterfly mariposa lily.
Bees were mobbing the soap plants.
Wednesday, May 21, 2008
My other hobby
Sometimes I go to parties and start beatboxing. Everybody just starts going wild, I'm that good. Here's a live recording from the last party I went to. Pretty sweet, right? I know, it's pretty impressive.
Tuesday, April 22, 2008
Monday, April 7, 2008
Racist
I just took tests at two sites to determine if I have subconscious racist biases. Here they are:
U Chicago
Harvard [the race IAT]
I first read about these in Malcolm Gladwell's Blink and then today in Nicholas Kristof's NY Times column. Apparently whites and blacks alike tend to associate blacks with negative things and whites with positive things. The tests are designed to access the subconscious through mind-numbingly repetitive tasks that measure implicit associations.
So go give them a try.
The U Chicago test has you shooting or choosing to not shoot a series of white and black men holding guns or cell phones. I shot whites with guns faster than blacks and I holstered my gun faster with blacks than with whites [no error bars were quoted, so I don't know if the results were statistically significant, but the difference appeared "large"]. This means that I am subconsciously biased anti-white. The second test is an association test and I scored dead even with no bias. I have many questions/complaints about the methodology but the general conclusion is that I test marvelously bias-free!
Everybody let me know how you do... and whether you measure up to my lofty precedent of high-minded anti-European American bigotry.
U Chicago
Harvard [the race IAT]
I first read about these in Malcolm Gladwell's Blink and then today in Nicholas Kristof's NY Times column. Apparently whites and blacks alike tend to associate blacks with negative things and whites with positive things. The tests are designed to access the subconscious through mind-numbingly repetitive tasks that measure implicit associations.
So go give them a try.
The U Chicago test has you shooting or choosing to not shoot a series of white and black men holding guns or cell phones. I shot whites with guns faster than blacks and I holstered my gun faster with blacks than with whites [no error bars were quoted, so I don't know if the results were statistically significant, but the difference appeared "large"]. This means that I am subconsciously biased anti-white. The second test is an association test and I scored dead even with no bias. I have many questions/complaints about the methodology but the general conclusion is that I test marvelously bias-free!
Everybody let me know how you do... and whether you measure up to my lofty precedent of high-minded anti-European American bigotry.
Wednesday, February 27, 2008
Evolution of Toxicity
How does defensive toxicity evolve? Being as I am completely ignorant of scientific orthodoxy on the topic, I am free to wildly speculate regarding this mystery.
Consider the monarch butterfly for a well-known example. As caterpillars, monarchs acquire a store of cardenolide aglycones from eating milkweed. These cardenolides are steroids that, in high enough doses, can stop the heart and thus are toxic to most animals. The monarchs then are permanently toxic to most predators from cardenolides ingested as a caterpillar and are thus protected from predation.
Storing cardenolides is a trait that must have evolved. Any investigation into the evolutionary history of a trait must begin with the Occam's Razor of evolutionary theory: the trait arose through random genetic mutation; it was beneficial to the reproductive viability of an individual monarch; this increase in viability eventually led to universal trait ownership in the global monarch population.
But how can this explanation be correct? Let us try to explicitly paint this story of the cardenolides-storing "gene" [standard euphemism for "gene or set of genes"]. We will start with a single monarch since identical genetic mutation in two distinct individuals is probabilistically impossible:
Consider further the role of the predator, in this example a bird. If not killed, the bird might learn not to eat monarchs again. Through cultural transmission the bird could possibly teach other birds not to eat monarchs. Even if such cultural transmission is likely, this benefits both the monarchs endowed with this gene and not, giving no evolutionary advantage to the gene itself [using a Dawkinsian gene-level evolutionary argument which is clearly valid trait-level as well]. If the bird was killed, on the other hand, then birds with a gene instructing them to not eat monarchs might replace the old ones after many generations. This scenario is less likely than the first; it requires a long period of large-scale predator/prey interactions with a monarch population significantly endowed with the gene, while simultaneously never giving any viability advantage to the cardenolides-storing monarchs. Neither explanation can account for selective pressures favoring the toxic gene.
Is there still some way to invoke basic adaptive natural selection for monarch toxicity? There is a candidate solution: taste. Cardenolides taste horrible. Is it possible that the bird tasted our monarch and rejected it? The butterfly then has received the ultimate survivability boost from the gene: it lives where its cousins would certainly have died. This is certainly possible, but I have strong doubts about this hypothesis. For one thing, I wonder about the state of a butterfly after being tasted by a bird. Is it likely that a tasted butterfly can survive and have offspring? It is true that this tasting could possibly leave the butterfly alive; this is why beak-marks on the wings of butterfly specimens are common. But what are a monarch's chances of reproducing after this injury? Additionally, any lesson the bird learned from the tasting the monarch--that all monarchs or even all butterflies taste terrible and are possibly toxic--will confer no specific advantage to the monarchs with the mutation. Remember that our one monarch, in order to pass on beneficial genes, will need to live in a situation where a monarch without the genes would die. Unless birds habitually sample butterflies in a non-fatal way before deciding to eat them, I find it extremely unlikely that it is taste that conferred the viability advantage for the monarchs with the toxic gene.
It is clear to me that the standard adaptive natural selection argument can't explain the toxicity trait of monarch butterflies. But exaptation--my old friend of herons and voles--could explain it well. Here's my explanation:
Cardenolides are not only toxic to birds, but insects as well. In fact, the toxins are used by plants specifically as a defense against being eaten by insects. Let us paint a different evolutionary story:
Suppose the gene for "immunity" is actually a gene for removing the cardenolides from the plant matter before digestion. This is one of several plausible methods for tolerating a toxin. The toxin thus must be excreted or stored. If the toxin is stored--or even if it persists a significant amount of time before being excreted--the monarchs will be toxic to birds. This toxicity is a by-product of the natural selection of the cardenolide-tolerant gene.
The benefit of this approach is that it allows the monarchs to acquire the toxic gene as a species. The downfall of the adaptive natural selection argument in the first place was that the gene had to be beneficial to the first butterfly in order to propagate. If the mutation had an initial evolutionary benefit--allowing access to new abundant food sources--then it will prevail throughout the species. Only then will the pressures of predation influence the evolution of these monarchs. Remember that all of our explanations for how the presence of the gene in the first individual gave it an evolutionary edge failed because all of those explanations gave the same advantage to the monarchs not possessing the mutation as to the monarchs with it. This failing is erased when the evolutionary impetus for the gene's survival is not dependent on being eaten or "tasted" to be expressed.
Now, as a species, the monarchs evolve better and better storage mechanisms for the toxins to be more effective at deterring predators. The predators evolve in parallel to learn not to eat monarchs.
This is exaptation.
This is also a "just-so story." But I would be surprised if toxicity in most prey animals is not a result of exaptation [there is a tantalizing genetic correlation between toxicity and coloration that broadcasts toxicity--like the red/black monarch wings--which seems to support my argument].
Update: I just found a paper [Ecological factors influencing the evolution of insects' chemical defenses, J. Skelhorn et al., Behavioral Ecology, doi:10.1093/beheco/arm115 ] discussing the evolution of defensive toxicity in insects. It says that the subject is relatively unexplored but gives this insight:
Update 2: I just realized that toxicity can be manufactured by the prey species, not just acquired through feed. This strongly suggests that the adaptive route is possible.
Consider the monarch butterfly for a well-known example. As caterpillars, monarchs acquire a store of cardenolide aglycones from eating milkweed. These cardenolides are steroids that, in high enough doses, can stop the heart and thus are toxic to most animals. The monarchs then are permanently toxic to most predators from cardenolides ingested as a caterpillar and are thus protected from predation.
Storing cardenolides is a trait that must have evolved. Any investigation into the evolutionary history of a trait must begin with the Occam's Razor of evolutionary theory: the trait arose through random genetic mutation; it was beneficial to the reproductive viability of an individual monarch; this increase in viability eventually led to universal trait ownership in the global monarch population.
But how can this explanation be correct? Let us try to explicitly paint this story of the cardenolides-storing "gene" [standard euphemism for "gene or set of genes"]. We will start with a single monarch since identical genetic mutation in two distinct individuals is probabilistically impossible:
- A single monarch is endowed through genetic mutation with the cardenolides-storing gene. Until the first interaction with a predator, this gene has no effect on the reproductive viability of the single butterfly.
- A bird eats the butterfly and dies or is injured from the toxin.
- The gene disappears.
Consider further the role of the predator, in this example a bird. If not killed, the bird might learn not to eat monarchs again. Through cultural transmission the bird could possibly teach other birds not to eat monarchs. Even if such cultural transmission is likely, this benefits both the monarchs endowed with this gene and not, giving no evolutionary advantage to the gene itself [using a Dawkinsian gene-level evolutionary argument which is clearly valid trait-level as well]. If the bird was killed, on the other hand, then birds with a gene instructing them to not eat monarchs might replace the old ones after many generations. This scenario is less likely than the first; it requires a long period of large-scale predator/prey interactions with a monarch population significantly endowed with the gene, while simultaneously never giving any viability advantage to the cardenolides-storing monarchs. Neither explanation can account for selective pressures favoring the toxic gene.
Is there still some way to invoke basic adaptive natural selection for monarch toxicity? There is a candidate solution: taste. Cardenolides taste horrible. Is it possible that the bird tasted our monarch and rejected it? The butterfly then has received the ultimate survivability boost from the gene: it lives where its cousins would certainly have died. This is certainly possible, but I have strong doubts about this hypothesis. For one thing, I wonder about the state of a butterfly after being tasted by a bird. Is it likely that a tasted butterfly can survive and have offspring? It is true that this tasting could possibly leave the butterfly alive; this is why beak-marks on the wings of butterfly specimens are common. But what are a monarch's chances of reproducing after this injury? Additionally, any lesson the bird learned from the tasting the monarch--that all monarchs or even all butterflies taste terrible and are possibly toxic--will confer no specific advantage to the monarchs with the mutation. Remember that our one monarch, in order to pass on beneficial genes, will need to live in a situation where a monarch without the genes would die. Unless birds habitually sample butterflies in a non-fatal way before deciding to eat them, I find it extremely unlikely that it is taste that conferred the viability advantage for the monarchs with the toxic gene.
It is clear to me that the standard adaptive natural selection argument can't explain the toxicity trait of monarch butterflies. But exaptation--my old friend of herons and voles--could explain it well. Here's my explanation:
Cardenolides are not only toxic to birds, but insects as well. In fact, the toxins are used by plants specifically as a defense against being eaten by insects. Let us paint a different evolutionary story:
- A single monarch is endowed through genetic mutation with some kind of immunity to cardenolides
- This monarch has access to food plants [as a caterpillar] that other monarchs do not. The immunity gene confers a strong advantage to this monarch at its most vulnerable stage of life.
- Because of increased survival rates as caterpillars, monarchs with the mutant genes proliferate and replace those without it
Suppose the gene for "immunity" is actually a gene for removing the cardenolides from the plant matter before digestion. This is one of several plausible methods for tolerating a toxin. The toxin thus must be excreted or stored. If the toxin is stored--or even if it persists a significant amount of time before being excreted--the monarchs will be toxic to birds. This toxicity is a by-product of the natural selection of the cardenolide-tolerant gene.
The benefit of this approach is that it allows the monarchs to acquire the toxic gene as a species. The downfall of the adaptive natural selection argument in the first place was that the gene had to be beneficial to the first butterfly in order to propagate. If the mutation had an initial evolutionary benefit--allowing access to new abundant food sources--then it will prevail throughout the species. Only then will the pressures of predation influence the evolution of these monarchs. Remember that all of our explanations for how the presence of the gene in the first individual gave it an evolutionary edge failed because all of those explanations gave the same advantage to the monarchs not possessing the mutation as to the monarchs with it. This failing is erased when the evolutionary impetus for the gene's survival is not dependent on being eaten or "tasted" to be expressed.
Now, as a species, the monarchs evolve better and better storage mechanisms for the toxins to be more effective at deterring predators. The predators evolve in parallel to learn not to eat monarchs.
This is exaptation.
This is also a "just-so story." But I would be surprised if toxicity in most prey animals is not a result of exaptation [there is a tantalizing genetic correlation between toxicity and coloration that broadcasts toxicity--like the red/black monarch wings--which seems to support my argument].
Update: I just found a paper [Ecological factors influencing the evolution of insects' chemical defenses, J. Skelhorn et al., Behavioral Ecology, doi:10.1093/beheco/arm115 ] discussing the evolution of defensive toxicity in insects. It says that the subject is relatively unexplored but gives this insight:
One potential explanation [for the evolution of defensive toxicity] is that chemically defended individuals suffer less from predation than those that do not invest in costly chemical defenses. However, chemical defense often cannot be detected prior to attack, meaning that in order for chemically defended individuals to suffer less from predation than visually similar undefended individuals, they must be more likely to survive predatory attacks. Although there is now some evidence that aposematic insects often survive predatory attacks relatively unharmed and that predators selectively reject prey based on their chemical content, it is currently unclear under what ecological circumstances such differences in survival would allow costly chemical defenses to evolve...This vindicates the premise for my theory but sheds some doubt on the need for it [the paper nowhere discusses the transmission of the gene from the first individual to further generations, but points to evidence that birds taste and release butterflies. And I was right about storing the toxic chemicals, it seems]. I still think exaptation is a cleaner explaination, but pure adaptative natural selection is more plausible in light of this. The paper is really good, it's worth a read.
...[A]lthough sequestered chemicals may be stored systemically in body tissues, many species store a large proportion of the chemicals in the integument and wings. This may increase the speed with which predators perceive an individual to be defended and as a result reduce damage to the insect.
Update 2: I just realized that toxicity can be manufactured by the prey species, not just acquired through feed. This strongly suggests that the adaptive route is possible.
Tuesday, February 26, 2008
Encyclopedia of Life
Last night I had the urge to look up the ecology of tank bromeliads. Not having a university biology library in my apartment, I turned to the internet. And found nothing. The "information superhighway" is supposed to be a glut of information; a curious Googler is supposed to be able to find anything. I have found this to be increasingly not the case. Very, very few resources provide deep, detailed, well-written material for the purpose of free information. Most of my searches return a superfluity of corporate garbage, functionally empty blogs, and woefully incomplete or inaccurate official pages. There are a few well-respected sites which provide high-quality information consistently--like the OED and Encyclopedia Britannica--but all have significant flaws; too narrow a scope, too little free content, or too-shallow coverage. Wikipedia has immensely broad but shallow and frighteningly inconsistent coverage. General Google searches are a major headache for anybody trying to find quality information. At every turn a researcher is bombarded with hundreds of irrelevant ads, search results, and links. I have found the internet to fall well short of its promise of being a powerful and accessible repository of the sum of human knowledge.
For these reasons I have been nearly beside myself with excitement for the last year in anticipation of the unveiling of the Encyclopdia of Life. The EOL will be the culmination of the internet, and by far its most important resource. In the words of E. O. Wilson, one of the coolest guys on the planet and the inspiration for the EOL:
And it's even better than that. Each page will eventually contain all known information about each species. It will accept user content, but only after screening by an expert, so the EOL will have the breadth of Wikipedia [within biology] with the information quality of a scientific journal. But the depth of information will be unlike any resource ever created by man. Seriously.
This morning I received this message in my inbox:
Woohoo! It is here--in abbreviated form, but it is here. I strongly urge you to go take it for a spin; the information format in revolutionary and brilliant.
Now when Little wakes up in the morning and asks to look at a picture of a kinkajou I don't have to rely on the crummy random pictures that Google image search returns...
Update: nytimes.com has a nice article on the unveiling of the EOL.
For these reasons I have been nearly beside myself with excitement for the last year in anticipation of the unveiling of the Encyclopdia of Life. The EOL will be the culmination of the internet, and by far its most important resource. In the words of E. O. Wilson, one of the coolest guys on the planet and the inspiration for the EOL:
Imagine an electronic page for each species of organism on Earth available everywhere by single access on command.
And it's even better than that. Each page will eventually contain all known information about each species. It will accept user content, but only after screening by an expert, so the EOL will have the breadth of Wikipedia [within biology] with the information quality of a scientific journal. But the depth of information will be unlike any resource ever created by man. Seriously.
This morning I received this message in my inbox:
The new Encyclopedia of Life portal has gone live with more than one million
species pages! In celebration of this big event, our first EOL newsletter is
available at:Click here to read the newsletter.
You can see the new pages at http://www.eol.org/. We also invite you to take the
survey at the site so you can help us improve.We thank you for your interest and
support over the past year. Enjoy.
Woohoo! It is here--in abbreviated form, but it is here. I strongly urge you to go take it for a spin; the information format in revolutionary and brilliant.
Now when Little wakes up in the morning and asks to look at a picture of a kinkajou I don't have to rely on the crummy random pictures that Google image search returns...
Update: nytimes.com has a nice article on the unveiling of the EOL.
Monday, January 28, 2008
Sub-bullet b: Antarctica
Sub-bullet b: "A clear warming trend is evidenced by the Antartctic ice sheets"
Hierarchy: Part II:1:A:iv:b
Back to Intro - Back to Outline - Up to Bullet iv - Back to Sub-bullet a - Forward to Sub-bullet c
Introduction:
Antarctica, like Greenland, has a complex climate and thus the logical structure of Sub-bullet a will be followed. Simply, this means that we will use current understanding of how warming could effect the ice in Antarctica and data showing the trends of the distribution of that ice to conclude whether warming is occurring. The issue of causality will be left at this point unless evidence can be found which attributes the observed behavior to effects other than warming.
The bulk of the ice on Antarctica consists of two main sheets: the East Antarctic Ice Sheet [EAIS] and the West Antarctic Ice Sheet [WAIS]. The EAIS is much higher in elevation and therefore colder and less susceptible to warming than the lower WAIS. Below is a map compiled by NASA's ICESat showing the altitude of the upper surface of the Antarctic ice sheet.
This uneven distribution of ice mass and altitude will be critical for understanding the behavior of the Antarctic ice sheet.
In most respects Antarctica is as different from Greenland as two polar ice sheets can possibly be. In contrast with Greenland, Antarctica is naturally very cold; a large majority of the surface area of the continent averages below freezing year-round. Since Anatarctica is less marginal for ice than Greenland, a small rise in temperature isn't likely to be the difference between ice and liquid water except at the extreme edges. This means that melting is relatively less important in Antarctica as a factor for mass loss. The interior is large and very cold and in this region scientists expect that a warming climate would increase the ice mass since precipitation would increase--perhaps even enough to make the total mass balance increase due to warming. The Antarctic peninsula sticks much farther north and thus is more susceptible to warming trends than the coasts. Antarctica also does not rely on an exterior ocean current to cool it, and contains over 10 times the ice that Greenland does. All of these factors make Antarctica theoretically much less sensitive to small climate effects as Greenland is.
Despite all of these differences, we are looking for the same warming signature for Antarctica as we were for Greenland: positive mass balance in the interior, potentially negative and accelerating mass balance at the edges [since thinning is not just related to melting but to ice dynamics like glacier flow], and glacial dynamics features like accelerating flow. A refinement of the mass balance model predicts that the WAIS will see mass loss and the EAIS will see mass gain; this is the signature we are looking for.
[Refer to bullet iv for further introductory material]
Study 1 : GRACE weighs in on mass balance
Measurements of Time-Variable Gravity Show Mass loss in Antarctica
Isabella Velicogna and John Wahr, Science 311, 1754 (2006)
Antarctic mass rates from GRACE
J. L. Chen et al., GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L11502
Interannual variations of the mass balance of the Antarctica and Greenland ice sheets from GRACE
G. Ramillien et al., Global and Planetary Change 53:3, 198-208 (2006)
Simple: The researchers who conducted two of the three of our GRACE studies for the Greenland mass balance trend also conducted similar studies for Antarctica, and another group worked on the data as well. Their conclusions are the same: interior mass is increasing, peripheral mass is decreasing, with a net decrease in mass that is quickly accelerating. See Sub-bullet a: Greenland for more GRACE discussion.
Details: All three studies found large negative mass balances in the WAIS and mass gain or balance in the EAIS. A figure from Velicogna and Wahr illustrates this [the green line is the EAIS trend and the red line is the WAIS trend]:
Mass balance findings for these three studies are summarized in the table below.
All three studies also corrected the data for post-glacial rebound--the upward swelling of the crust resulting from the loss of glacial period ice--which yields more accurate but less precise data, since the post-glacial rebound is poorly known. Chen et al. describes the limit of knowledge [units, parenthetical statement and emphasis mine]:
"The calculations here show that the estimates of Antarctic snow/ice mass rates from GRACE data are completely dependent on the adopted PGR [post-glacial rebound] model, with uncertainties that might be on the order of 100% Our estimate of -99 or -77 cubic kilometers per year mass loss in West Antarctica is consistent with that of Velicogna and Wahr of -148 cubic kilometers per year, given the large PGR uncertainty and that here we only compute the mass loss of the Amundsen Sea Embayment in West Antarctica."
The take-home message is that we shouldn't have much faith in the exact numerical values of the mass balance, but that the trend of mass loss in the WAIS and mass gain in the EAIS is clear.
Discussion: The two studies with the most comprehensive geographical scope [Velicogna and Wahr and Remillien et al. ] agree within quoted error limits. The total mass balance isn't the first clue to a warming climate that Antarctica offers anyway [although it's the driving global factor in sea-level change, which has the potential for enormous effects]. What is important is also what is clear from the data: Antarctica is undeniably showing the signs of warming--decreasing ice mass in the WAIS and increasing or stable ice mass in the EAIS.
Conclusion: The GRACE data constitute strong evidence of a south polar warming trend.
Study 2: Sattelite radar altimetry measures mass balance
Mass changes of the Greenland and Antarctic ice sheets and shelves and contributions to sea-level rise: 1992–2002
H. Jay Zwally et al., Journal of Glaciology, Vol. 51, No. 175, 2005
Not-yet-published sattelite radar altimetry Antarctic mass balance study
Eric Rignot
Simple: The European remote sensing sattelites ERS-1 and -2 used radar altimetry to measure the altitude of ice in the Antarctic ice sheets. The first study is comprised of data from 1992-2002 which shows a mass loss in the WAIS and a mass gain in the EAIS which contributed to an overall negative mass balance. Additionally, the as-yet-unpublished second study--another by Eric Rignot--apparently fuses newer ERS-1 and -2 data with similar data from Japanese and Canadian sattelites and finds that ice loss in the WAIS increased extremely sharply during the decade 1996-2006.
Details: Covering a time period prior to most of the studies we've seen so far, the first ERS data is crucial in establishing a longer-term trend. This analysis is the most sophisticated to come out of the ERS program; the authors attempt to correct for some small but important factors which most other studies ignore, having to do with the dynamics of ice compaction. The dH/dt [rate of change of ice sheet altitude] map below represents the corrected data from Zwally et al.:
Rignot's technique is different than Zwally's; Rignot measures the amount of ice leaving the continent indirectly, by monitoring the flow of ice off the continent in glaciers. The benefit of this method is that it allows the researchers to ignore the problems that Zwally had to design sophisticated corrections for, such as the sensitivity of compactibility of new ice to temperature. Additionally, Rignot combined many different large datasets and has data up to 2006, greatly enhancing the completeness and relevancy of the data.
Quote from article on Rignot's upcoming paper: "The team found that the net loss of ice mass from Antarctica increased from 112 (plus or minus 91) gigatonnes a year in 1996 to 196 (plus or minus 92) gigatonnes a year in 2006."
Zwally et al. Quote: "The ice sheet inWest Antarctica (WA) is losing mass (–47 +/- 4Gt per year) and the ice sheet in East Antarctica (EA) shows a small mass gain (+16 +/- 11 Gt per year) for a combined net change of –31+/- 12 Gt per year (+0.08mma–1 SLE). "
Discussion: The data from this study solidly confirms the existence of the bimodial east/west mass gain/loss signature in Antarctica; the signature of warming. Furthermore, Rignot's study--which used data from the same sources and identical analysis--found solid evidence that the ice mass loss in Antarctica is accelerating at a phenomenal pace; a solid sign of warming. Two more sattelite radar altimetry studies, Wingham et al. and Davis and Li found a slight mass increase. However, both of these studies found it difficult to analyze the peripheral regions and thus left them out of the analysis altogether. Since a majority of the loss we see occurs at the periphery, these studies do nothing but confirm the other studies' findings of a mass increase in the interior.
[Zwally et al. study also analyzed the Greenland ice sheet and found a small positive mass balance, which is not inconsistent with the studies reported in the Greenland section for this time period]
Conclusion: The ERS data constitutes evidence of a south polar warming trend.
Study 3: Laser altimetry analyzes glacial dynamics
Accelerated sea-level rise from West Antarctica
Thomas, Rignot, et al., Science 8 October 2004:Vol. 306. no. 5694, pp. 255 - 258
Simple: Using laser altimetry data from sattelites and aircraft, Thomas et al. have measured the discharge from the glaciers in a section of the WAIS. They discovered a steeply accelerating flow from the 1990's until 2003; a glacier dynamics marker indicative of warming.
Details: Thomas et al. found that 60% more ice was flowing out of the catchment basin feeding the Amundsen sea in west Antarctica than was accumulating due to precipitation. They collected precise ice thickness data from aircraft flown from Chile and compared it with various sattelite data sets to create a map of ice thinning rates for the catchment area. A quote: "The catchment regions of Amundsen Sea glaciers contain enough ice to raise sea level by 1.3 m. Our measurements show them collectively to be 60% out of balance, sufficient to raise sea level by 0.24 mm/year. Although these glaciers are the fastest in Antarctica, they are likely to flow considerably faster once the ice shelves are removed and glacier retreat proceeds into the deeper part of glacier basins."
Discussion: Not only does this large imbalance of outflow/inflow point to conditions now being different than they were previously, but the study reports an acceleration of the imbalance, which signifies compounding factors in recent years. Even more impressive is the potential for yet higher rates of mass loss when/if the ice shelves melt, effectively pulling the rug out from under the glaciers.
Conclusion: This glacial dynamics study constitutes strong evidence of south polar warming.
Other studies
Recent sea-level contributions of the Antarctic and Greenland ice sheets
Andrew Shepherd and Duncan Wingham, Science 315, 1529 (2007)
Simple: This is a review of mass-balance data. It does a much better job than I can, and it reviews most of the same data I have.
Mass balance of polar ice sheets
Eric Rignot and Robert H. Thomas
Simple: Another review but older. Same conclusions.
[Further studies requested]
Discussion
The evidence is accumulating and the doubt is thinning; the Antarctic ice sheets are shrinking at fantastic rates, and the rate of increase is itself increasing at a fantastic rate. Two years ago there might have been argument, but at this point it is obvious that something big is cooking at the south pole. The issue of causality is less complicated than Greenland, but still the strongest statement we can make is that warming is the only candidate known for the cause of the changes observed. Given the scale of the changes--and the recently discovered fact that ice outflow increases dramatically after ice shelves melt--I feel comfortable agreeing with the large majority of these researchers in this point: the loss of ice in Antarctica will likely reach astonishing proportions in the near future if current conditions persist. Two ice shelves collapsed in the last few years, triggering massive acceleration of glacial flow, and similar events should be expected in the near future.
A summary of the mass balance studies cited in this post:
Conclusion
This data constitutes strong evidence of north polar warming.
Sub-bullet value: TRUE
Hierarchy: Part II:1:A:iv:b
Back to Intro - Back to Outline - Up to Bullet iv - Back to Sub-bullet a - Forward to Sub-bullet c
Introduction:
Antarctica, like Greenland, has a complex climate and thus the logical structure of Sub-bullet a will be followed. Simply, this means that we will use current understanding of how warming could effect the ice in Antarctica and data showing the trends of the distribution of that ice to conclude whether warming is occurring. The issue of causality will be left at this point unless evidence can be found which attributes the observed behavior to effects other than warming.
The bulk of the ice on Antarctica consists of two main sheets: the East Antarctic Ice Sheet [EAIS] and the West Antarctic Ice Sheet [WAIS]. The EAIS is much higher in elevation and therefore colder and less susceptible to warming than the lower WAIS. Below is a map compiled by NASA's ICESat showing the altitude of the upper surface of the Antarctic ice sheet.
This uneven distribution of ice mass and altitude will be critical for understanding the behavior of the Antarctic ice sheet.In most respects Antarctica is as different from Greenland as two polar ice sheets can possibly be. In contrast with Greenland, Antarctica is naturally very cold; a large majority of the surface area of the continent averages below freezing year-round. Since Anatarctica is less marginal for ice than Greenland, a small rise in temperature isn't likely to be the difference between ice and liquid water except at the extreme edges. This means that melting is relatively less important in Antarctica as a factor for mass loss. The interior is large and very cold and in this region scientists expect that a warming climate would increase the ice mass since precipitation would increase--perhaps even enough to make the total mass balance increase due to warming. The Antarctic peninsula sticks much farther north and thus is more susceptible to warming trends than the coasts. Antarctica also does not rely on an exterior ocean current to cool it, and contains over 10 times the ice that Greenland does. All of these factors make Antarctica theoretically much less sensitive to small climate effects as Greenland is.
Despite all of these differences, we are looking for the same warming signature for Antarctica as we were for Greenland: positive mass balance in the interior, potentially negative and accelerating mass balance at the edges [since thinning is not just related to melting but to ice dynamics like glacier flow], and glacial dynamics features like accelerating flow. A refinement of the mass balance model predicts that the WAIS will see mass loss and the EAIS will see mass gain; this is the signature we are looking for.
[Refer to bullet iv for further introductory material]
Study 1 : GRACE weighs in on mass balance
Measurements of Time-Variable Gravity Show Mass loss in Antarctica
Isabella Velicogna and John Wahr, Science 311, 1754 (2006)
Antarctic mass rates from GRACE
J. L. Chen et al., GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L11502
Interannual variations of the mass balance of the Antarctica and Greenland ice sheets from GRACE
G. Ramillien et al., Global and Planetary Change 53:3, 198-208 (2006)
Simple: The researchers who conducted two of the three of our GRACE studies for the Greenland mass balance trend also conducted similar studies for Antarctica, and another group worked on the data as well. Their conclusions are the same: interior mass is increasing, peripheral mass is decreasing, with a net decrease in mass that is quickly accelerating. See Sub-bullet a: Greenland for more GRACE discussion.
Details: All three studies found large negative mass balances in the WAIS and mass gain or balance in the EAIS. A figure from Velicogna and Wahr illustrates this [the green line is the EAIS trend and the red line is the WAIS trend]:
Mass balance findings for these three studies are summarized in the table below.
All three studies also corrected the data for post-glacial rebound--the upward swelling of the crust resulting from the loss of glacial period ice--which yields more accurate but less precise data, since the post-glacial rebound is poorly known. Chen et al. describes the limit of knowledge [units, parenthetical statement and emphasis mine]:"The calculations here show that the estimates of Antarctic snow/ice mass rates from GRACE data are completely dependent on the adopted PGR [post-glacial rebound] model, with uncertainties that might be on the order of 100% Our estimate of -99 or -77 cubic kilometers per year mass loss in West Antarctica is consistent with that of Velicogna and Wahr of -148 cubic kilometers per year, given the large PGR uncertainty and that here we only compute the mass loss of the Amundsen Sea Embayment in West Antarctica."
The take-home message is that we shouldn't have much faith in the exact numerical values of the mass balance, but that the trend of mass loss in the WAIS and mass gain in the EAIS is clear.
Discussion: The two studies with the most comprehensive geographical scope [Velicogna and Wahr and Remillien et al. ] agree within quoted error limits. The total mass balance isn't the first clue to a warming climate that Antarctica offers anyway [although it's the driving global factor in sea-level change, which has the potential for enormous effects]. What is important is also what is clear from the data: Antarctica is undeniably showing the signs of warming--decreasing ice mass in the WAIS and increasing or stable ice mass in the EAIS.
Conclusion: The GRACE data constitute strong evidence of a south polar warming trend.
Study 2: Sattelite radar altimetry measures mass balance
Mass changes of the Greenland and Antarctic ice sheets and shelves and contributions to sea-level rise: 1992–2002
H. Jay Zwally et al., Journal of Glaciology, Vol. 51, No. 175, 2005
Not-yet-published sattelite radar altimetry Antarctic mass balance study
Eric Rignot
Simple: The European remote sensing sattelites ERS-1 and -2 used radar altimetry to measure the altitude of ice in the Antarctic ice sheets. The first study is comprised of data from 1992-2002 which shows a mass loss in the WAIS and a mass gain in the EAIS which contributed to an overall negative mass balance. Additionally, the as-yet-unpublished second study--another by Eric Rignot--apparently fuses newer ERS-1 and -2 data with similar data from Japanese and Canadian sattelites and finds that ice loss in the WAIS increased extremely sharply during the decade 1996-2006.
Details: Covering a time period prior to most of the studies we've seen so far, the first ERS data is crucial in establishing a longer-term trend. This analysis is the most sophisticated to come out of the ERS program; the authors attempt to correct for some small but important factors which most other studies ignore, having to do with the dynamics of ice compaction. The dH/dt [rate of change of ice sheet altitude] map below represents the corrected data from Zwally et al.:
Rignot's technique is different than Zwally's; Rignot measures the amount of ice leaving the continent indirectly, by monitoring the flow of ice off the continent in glaciers. The benefit of this method is that it allows the researchers to ignore the problems that Zwally had to design sophisticated corrections for, such as the sensitivity of compactibility of new ice to temperature. Additionally, Rignot combined many different large datasets and has data up to 2006, greatly enhancing the completeness and relevancy of the data.
Quote from article on Rignot's upcoming paper: "The team found that the net loss of ice mass from Antarctica increased from 112 (plus or minus 91) gigatonnes a year in 1996 to 196 (plus or minus 92) gigatonnes a year in 2006."
Zwally et al. Quote: "The ice sheet inWest Antarctica (WA) is losing mass (–47 +/- 4Gt per year) and the ice sheet in East Antarctica (EA) shows a small mass gain (+16 +/- 11 Gt per year) for a combined net change of –31+/- 12 Gt per year (+0.08mma–1 SLE). "
Discussion: The data from this study solidly confirms the existence of the bimodial east/west mass gain/loss signature in Antarctica; the signature of warming. Furthermore, Rignot's study--which used data from the same sources and identical analysis--found solid evidence that the ice mass loss in Antarctica is accelerating at a phenomenal pace; a solid sign of warming. Two more sattelite radar altimetry studies, Wingham et al. and Davis and Li found a slight mass increase. However, both of these studies found it difficult to analyze the peripheral regions and thus left them out of the analysis altogether. Since a majority of the loss we see occurs at the periphery, these studies do nothing but confirm the other studies' findings of a mass increase in the interior.
[Zwally et al. study also analyzed the Greenland ice sheet and found a small positive mass balance, which is not inconsistent with the studies reported in the Greenland section for this time period]
Conclusion: The ERS data constitutes evidence of a south polar warming trend.
Study 3: Laser altimetry analyzes glacial dynamics
Accelerated sea-level rise from West Antarctica
Thomas, Rignot, et al., Science 8 October 2004:Vol. 306. no. 5694, pp. 255 - 258
Simple: Using laser altimetry data from sattelites and aircraft, Thomas et al. have measured the discharge from the glaciers in a section of the WAIS. They discovered a steeply accelerating flow from the 1990's until 2003; a glacier dynamics marker indicative of warming.
Details: Thomas et al. found that 60% more ice was flowing out of the catchment basin feeding the Amundsen sea in west Antarctica than was accumulating due to precipitation. They collected precise ice thickness data from aircraft flown from Chile and compared it with various sattelite data sets to create a map of ice thinning rates for the catchment area. A quote: "The catchment regions of Amundsen Sea glaciers contain enough ice to raise sea level by 1.3 m. Our measurements show them collectively to be 60% out of balance, sufficient to raise sea level by 0.24 mm/year. Although these glaciers are the fastest in Antarctica, they are likely to flow considerably faster once the ice shelves are removed and glacier retreat proceeds into the deeper part of glacier basins."
Discussion: Not only does this large imbalance of outflow/inflow point to conditions now being different than they were previously, but the study reports an acceleration of the imbalance, which signifies compounding factors in recent years. Even more impressive is the potential for yet higher rates of mass loss when/if the ice shelves melt, effectively pulling the rug out from under the glaciers.
Conclusion: This glacial dynamics study constitutes strong evidence of south polar warming.
Other studies
Recent sea-level contributions of the Antarctic and Greenland ice sheets
Andrew Shepherd and Duncan Wingham, Science 315, 1529 (2007)
Simple: This is a review of mass-balance data. It does a much better job than I can, and it reviews most of the same data I have.
Mass balance of polar ice sheets
Eric Rignot and Robert H. Thomas
Simple: Another review but older. Same conclusions.
[Further studies requested]
Discussion
The evidence is accumulating and the doubt is thinning; the Antarctic ice sheets are shrinking at fantastic rates, and the rate of increase is itself increasing at a fantastic rate. Two years ago there might have been argument, but at this point it is obvious that something big is cooking at the south pole. The issue of causality is less complicated than Greenland, but still the strongest statement we can make is that warming is the only candidate known for the cause of the changes observed. Given the scale of the changes--and the recently discovered fact that ice outflow increases dramatically after ice shelves melt--I feel comfortable agreeing with the large majority of these researchers in this point: the loss of ice in Antarctica will likely reach astonishing proportions in the near future if current conditions persist. Two ice shelves collapsed in the last few years, triggering massive acceleration of glacial flow, and similar events should be expected in the near future.
A summary of the mass balance studies cited in this post:
Conclusion
This data constitutes strong evidence of north polar warming.
Sub-bullet value: TRUE
Tuesday, January 22, 2008
Sub-bullet a: Greenland
Sub-bullet a: "A clear warming trend is evidenced by the Greenland ice sheet"
Hierarchy: Part II:1:A:iv:a
Back to Intro - Back to Outline - Up to Bullet iv - Forward to Sub-bullet b
Introduction:
Greenland holds nearly 10% of all the ice in the world. Given its relatively southerly location, Greenland's ice is balanced precariously between its current state and cataclysmic melting, kept stable only by virtue of a microclimate controlled by the ice itself and by friendly and cold arctic ocean currents. The ice is so thick that the crust of Greenland is depressed in the interior from the weight of it. Warming should be relatively easy to spot here; many scientists think that Greenland is close to a sharp equilibrium point and that warming will cause a chain of " positive feedbacks"--some warming will trigger factors which compound the warming and trigger other factors, etc. Thus the changes in the Greenland ice sheet might happen quicker than expected given the large thermal inertia that such a huge block of ice has.
Greenland's climate is an anomaly when placed in the context of other land masses at its latitude. When my family traveled to Prudhoe Bay, AK this last summer, we found it warm and ice-free. Prudhoe Bay is at the northern edge of Alaska, at a latitude of 70 N [for comparison, Anchorage is at 61 N]. Greenland's permanent ice extends down to about 60 N, so far south that almost all of Alaska and the northern territories of Canada would be under ice if Greenland's ice sheet was typical. Why is Greenland covered in ice when most of the latitudes it occupies are free of ice elsewhere?
The glib answer is: because Greenland is colder than other areas at the same latitude. A little background is needed before we can answer why.
Greenland's ice sheet was formed during one of the many colder periods in the earth's history. These glacial periods have caused the latitude marking the ice sheet boundary to move southward, at times reaching down into the continental United States. About 10,000 years ago the last major ice age ended and temperatures returned to roughly what they are now. The equilibrium latitude shifted much farther north in a short period of time. The bulk of the ice sheets were now below the equilibrium latitude, and thus started slowly retreating northward. The retreat was so slow that it is probable that the remaining continental glaciers are still retreating to this day. For some reason, though, Greenland never got the message; some particular climate conditions caused the local equilibrium latitude around Greenland to be stuck farther south than it is for the rest of the Northern Hemisphere. It turns out that this effect is due to two main things: the East Greenland Current, an ocean current that cools Greenland's climate through shipping cold water right along the east coast Greenland from the Arctic; and the high altitude of the ice sheet in Greenland, which keeps the sheet colder than its latitude would dictate.
Warming would effect Greenland in very complex ways, and since the climate is dictated by an ocean current, understanding the subtleties of the current's response to warming would normally be critical to understanding the effect on Greenland's ice sheets. It would be impossible to delve into those subtleties here--albedo, salinity, feedback--but we can still draw some conclusions if the effects are clear enough. This requires an explicit logic that needs explaining: given the "well, duh" aspect of the statement "ice will melt more if temperatures increase" and also given that regional models predict a certain pattern of melting occurring as the result of the warming, IF expected melting patterns are conclusively observed, THEN the region is almost certainly warming. The burden of proof to the contrary will rest on those who wish to prove that the melting proceeds by some other mechanism.
I am not trying to cover up a logical flaw. Rather, I'm using the strongest logic that is possible in any kind of analysis of complex systems. A researcher can never be 100% confident in a causality solution in a system this complex, but it is not wrong to draw conclusions based on the best available data, assuming that as much rigor as is possible is dedicated to trying to understand the underlying causes and effects. Such a case this is. What this means practically is that we will look at the data, conclude confidently based on this data that it is TRUE or FALSE that the behavior of Greenland proves regional warming. The bullet value will only stay TRUE if sufficient evidence is not found for mechanisms other than warming causing the observed effects.
[Refer to bullet iv for further introductory material]
Study 1
Greenland mass balance from GRACE
Isabella Velicogna and John Wahr, GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L18505
Satellite gravity measurements confirm accelerated melting of Greenland ice sheet
J. L. Chen, et al., Science 313, 1958 (2006)
Recent Greenland ice mass loss by drainage system from sattelite gravity observations
S. B. Luthcke, et al., Science 314, 1286 (2006)
Basic: These papers utilize data from the GRACE experiment, with newer data in the second and third papers. This is the type of experiment every researcher would love to be part of. GRACE is a fantastic idea: two orbiting satellites working in tandem to measure the gravitational field above the earth. This is an exquisitely delicate experiment, but it was pulled off and is very successful. The idea is that ice will "pull" on the spacecraft through gravitational acceleration. This pull is measured each time the satellite passes over and compared across time. If the pull changes, that means that ice is accumulating or being lost on the ice sheet. The beauty of this approach is that it is independent of ice transport mechanism and is the first experiment that is directly measuring the quantity of ice present as opposed to indirect studies of depth or flow which use generous extrapolations and interpolations. The first study includes data from 2002-2004 and the second and third studies adds 2005 to that. The studies concluded that the mass balance of Greenland in the time period was large, negative, and accelerating, consistent with regional warming.
Details: Velicogna and Wahr: "We recover a decrease in total ice mass of 82 ± 28 km3 of ice per year." I am unable to access the rest of the paper, so I would appreciate anybody with an AGU membership to help me on this one. Again, although static or increasing mass balance is inconclusive, negative mass balance, especially one this large, is very strong evidence of warming. The image below, taken from the NASA site supporting this research, shows a very strong net mass loss around the periphery of Greenland and a small mass gain in the interior.
Although less comprehensive than the GRACE survey, it is clear that a large negative mass balance at the periphery of Greenland overwhelms the accumulation in the interior.
Hierarchy: Part II:1:A:iv:a
Back to Intro - Back to Outline - Up to Bullet iv - Forward to Sub-bullet b
Introduction:
Greenland holds nearly 10% of all the ice in the world. Given its relatively southerly location, Greenland's ice is balanced precariously between its current state and cataclysmic melting, kept stable only by virtue of a microclimate controlled by the ice itself and by friendly and cold arctic ocean currents. The ice is so thick that the crust of Greenland is depressed in the interior from the weight of it. Warming should be relatively easy to spot here; many scientists think that Greenland is close to a sharp equilibrium point and that warming will cause a chain of " positive feedbacks"--some warming will trigger factors which compound the warming and trigger other factors, etc. Thus the changes in the Greenland ice sheet might happen quicker than expected given the large thermal inertia that such a huge block of ice has.
Greenland's climate is an anomaly when placed in the context of other land masses at its latitude. When my family traveled to Prudhoe Bay, AK this last summer, we found it warm and ice-free. Prudhoe Bay is at the northern edge of Alaska, at a latitude of 70 N [for comparison, Anchorage is at 61 N]. Greenland's permanent ice extends down to about 60 N, so far south that almost all of Alaska and the northern territories of Canada would be under ice if Greenland's ice sheet was typical. Why is Greenland covered in ice when most of the latitudes it occupies are free of ice elsewhere?
The glib answer is: because Greenland is colder than other areas at the same latitude. A little background is needed before we can answer why.
Greenland's ice sheet was formed during one of the many colder periods in the earth's history. These glacial periods have caused the latitude marking the ice sheet boundary to move southward, at times reaching down into the continental United States. About 10,000 years ago the last major ice age ended and temperatures returned to roughly what they are now. The equilibrium latitude shifted much farther north in a short period of time. The bulk of the ice sheets were now below the equilibrium latitude, and thus started slowly retreating northward. The retreat was so slow that it is probable that the remaining continental glaciers are still retreating to this day. For some reason, though, Greenland never got the message; some particular climate conditions caused the local equilibrium latitude around Greenland to be stuck farther south than it is for the rest of the Northern Hemisphere. It turns out that this effect is due to two main things: the East Greenland Current, an ocean current that cools Greenland's climate through shipping cold water right along the east coast Greenland from the Arctic; and the high altitude of the ice sheet in Greenland, which keeps the sheet colder than its latitude would dictate.
Warming would effect Greenland in very complex ways, and since the climate is dictated by an ocean current, understanding the subtleties of the current's response to warming would normally be critical to understanding the effect on Greenland's ice sheets. It would be impossible to delve into those subtleties here--albedo, salinity, feedback--but we can still draw some conclusions if the effects are clear enough. This requires an explicit logic that needs explaining: given the "well, duh" aspect of the statement "ice will melt more if temperatures increase" and also given that regional models predict a certain pattern of melting occurring as the result of the warming, IF expected melting patterns are conclusively observed, THEN the region is almost certainly warming. The burden of proof to the contrary will rest on those who wish to prove that the melting proceeds by some other mechanism.
I am not trying to cover up a logical flaw. Rather, I'm using the strongest logic that is possible in any kind of analysis of complex systems. A researcher can never be 100% confident in a causality solution in a system this complex, but it is not wrong to draw conclusions based on the best available data, assuming that as much rigor as is possible is dedicated to trying to understand the underlying causes and effects. Such a case this is. What this means practically is that we will look at the data, conclude confidently based on this data that it is TRUE or FALSE that the behavior of Greenland proves regional warming. The bullet value will only stay TRUE if sufficient evidence is not found for mechanisms other than warming causing the observed effects.
[Refer to bullet iv for further introductory material]
Study 1
Greenland mass balance from GRACE
Isabella Velicogna and John Wahr, GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L18505
Satellite gravity measurements confirm accelerated melting of Greenland ice sheet
J. L. Chen, et al., Science 313, 1958 (2006)
Recent Greenland ice mass loss by drainage system from sattelite gravity observations
S. B. Luthcke, et al., Science 314, 1286 (2006)
Basic: These papers utilize data from the GRACE experiment, with newer data in the second and third papers. This is the type of experiment every researcher would love to be part of. GRACE is a fantastic idea: two orbiting satellites working in tandem to measure the gravitational field above the earth. This is an exquisitely delicate experiment, but it was pulled off and is very successful. The idea is that ice will "pull" on the spacecraft through gravitational acceleration. This pull is measured each time the satellite passes over and compared across time. If the pull changes, that means that ice is accumulating or being lost on the ice sheet. The beauty of this approach is that it is independent of ice transport mechanism and is the first experiment that is directly measuring the quantity of ice present as opposed to indirect studies of depth or flow which use generous extrapolations and interpolations. The first study includes data from 2002-2004 and the second and third studies adds 2005 to that. The studies concluded that the mass balance of Greenland in the time period was large, negative, and accelerating, consistent with regional warming.
Details: Velicogna and Wahr: "We recover a decrease in total ice mass of 82 ± 28 km3 of ice per year." I am unable to access the rest of the paper, so I would appreciate anybody with an AGU membership to help me on this one. Again, although static or increasing mass balance is inconclusive, negative mass balance, especially one this large, is very strong evidence of warming. The image below, taken from the NASA site supporting this research, shows a very strong net mass loss around the periphery of Greenland and a small mass gain in the interior.
This figure, from Velicogna and Wehr, shows the total Greenland ice sheet mass observed by GRACE during the study:
The second study confirms this data and adds a crucial fact: melting accelerated even within the limited time scale of the study. This acceleration is evident in the following plots from Chen:
The second study revises the yearly net mass loss upwards and confirms the acceleration of mass lost at least on this small time scale.
The third study confirms the main results of the other studies but lowers the mass loss estimate from the second study.
GRACE tells us that the Greenland ice sheet is melting and by how much. But even more significant is that this melting is accelerating on a seasonal timescale. This is a crucial piece of the puzzle; receding glaciers can be attributed to "ice age rebound"--the still on-going process of ice retreat from the last ice age, when the ice sheets were much more expansive. But acceleration of melting can only be due to warming: rebound predicts a gradual deceleration of ice loss as the equilibrium point is approached.
Conclusion: GRACE data provides very strong evidence of north polar warming.
Study 2
Greenland ice sheet: high-altitude balance and peripheral thinning
W. Krabill, et. al., Science 21 July 2000:Vol. 289. no. 5478, pp. 428 - 430
Basic: Greenland ice sheet: high-altitude balance and peripheral thinning. What more to say?
Details: This study was conducted using laser altimetry from aircraft; this is how it was done before GRACE. Laser altimitry can only tell you the altitude of the surface of the ice so this approach is most useful for mass balance studies. The study specifically addressed the mass balance of Greenland. Above 2000m of altitude, there was a mass balance: net accumulation in the northern latitudes counteracted net loss in the southern latitudes. However, at all latitudes around the periphery there was widespread net loss. An included figure best describes the findings [flight tracks shown; also note that this is an elevation chart, not a mass chart like for GRACE]:
Although less comprehensive than the GRACE survey, it is clear that a large negative mass balance at the periphery of Greenland overwhelms the accumulation in the interior.In sum: "Interpolation of our results between flight lines indicates a net loss of about 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise global sea level by 0.13 millimeter per year--approximately 7% of the observed rise."
Discussion: This study found strong evidence for behavior which points to warming: ice thickening or balance in the interior and aggressive thinning at the periphery. However, the authors admit that the peripheral thinning cannot be explained by the temperature record alone, and that the mechanism for the mass loss is still a mystery. Study 3 below is a partial response to this study and attempts to solve this problem with glacial dynamics studies.
Conclusion: This study gives some evidence for north polar warming.
Study 3
Changes in the velocity structure of the Greenland ice sheet
Eric Rignot and Pannir Kanagaratnam , Science 17 February 2006 311: 986-990
Basic: Using data from satellite radar interferometry [bouncing electromagnetic waves off the surface of ice from space], Rignot and Kanagaratnam have measured the velocity of the glaciers of Greenland over the last decade. Note how this differs from the previous study: the altimetry data presented in Study 2 likewise bounced electromagnetic waves [in that case, lasers] off the surface of the ice sheet, but there it was for the purpose of measuring the altitude of the ice surface and in this study the purpose is to measure the speed at which the ice flows down glaciers. These glaciers are the conveyor belts for ice transportation from the interior of Greenland to the sea, so glacial acceleration is a sign that more ice is leaving Greenland and entering the oceans. The study not only found widespread glacial acceleration, but found that the portion of Greenland experiencing the acceleration is increasing dramatically. The effect is also found to dominate any increase in due to warming, and is presented as an explanation for the mechanisms behind the results found in Study 2.
Detailed: The causes of glacial acceleration are not very well known, although all plausible explanations are products of warming [such as surface meltwater percolating down under the ice and lubricating the interface between ice and rock]. The degree of acceleration is also not a terribly good measure of the warming; all it can say is that warming is occurring. The study found that total mass loss from Greenland doubled in the period 1996-2005. The important point is that acceleration is observed, and this is not a feature of ice age rebound. The authors state: "We detected widespread glacier acceleration below 66 [degrees] north between 1996 and 2000, which rapidly expanded to 70 [degrees] north in 2005. Accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year."
The figure below shows the velocity plots of some of the glaciers from the study. The black lines correspond to the oldest data, blue the next, and red the most recent. Since these are velocity plots, the earmark of acceleration will be the red plots lying "above" the blue ones and the blue ones above the black ones.
Conclusion: This study constitutes strong evidence of north polar warming.
Other studies
Progressive increase in ice mass loss from Greenland
R. Thomas, et al., GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L10503
Basic: Similar results from the ICEsat experiment.
Quote: "Laser altimeter measurements over Greenland show increasing thickening rates bove 2000 m, reflecting increasing snowfall in a warming climate. But near-coastal thinning rates have increased substantially since the mid 1990s, and net mass loss more than doubled from an average of 4–50 Gt per year between 1993/4 and 1998/9 to 57–105 Gt per year between 1998/9 and 2004. This increasing trend is very similar to findings from independent massbudget studies, but differs widely from ERS radar altimeter results."
Runoff and mass balance of the Greenland ice sheet: 1958–2003
Edward Hanna et. al., JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, D13108
Quote: "Runoff losses from the ice sheet were 264 (±26) km3 yr−1 in 1961–1990 and 372 (±37) km3 yr−1 in 1998–2003. Significantly rising runoff since the 1990s has been partly offset by increased precipitation. Our best estimate of overall mass balance declined from 22 (±51) km3 yr−1 in 1961–1990 to −36 (±59) km3 yr−1 in 1998–2003, which is not statistically significant."
The Greenland ice sheet and global sea-level rise
Julian A. Dowdeswell
Abstract: "The flow of several large glaciers draining the Greenland Ice Sheet is accelerating. This change,combined with increased melting, suggests that existing estimates of future sea-level rise are too low."
Seasonality and increasing frequency of Greenland glacial earthquakes
Göran Ekström, et al., Science 311, 1756 (2006)
Abstract: "Some glaciers and ice streams periodically lurch forward with sufficient force to generate emissions of elastic waves that are recorded on seismometers worldwide. Such glacial earthquakes on Greenland show a strong seasonality as well as a doubling of their rate of occurrence over the past 5 years. These temporal patterns suggest a link to the hydrological cycle and are indicative of a dynamic glacial response to changing climate conditions."
[Further studies requested]
Discussion
There is no doubt that Greenland is losing ice. And fast. A valid argument against concluding that warming is the cause of the loss is still present, however: since Greenland's climate is so controlled by the East Greenland Current [EGC], it is possible that the current is changing in ways that is encouraging the loss of ice on Greenland. The GRACE mass deficit maps are particularly encouraging to this line of thinking since a large majority of the mass loss occurs along the eastern coast, where Greenland and the current interface. I have dug deep to find evidence that the EGC has changed in any way since before the mass balance turned negative. I found no such evidence. Additionally, any change in the EGC could very well be tied to warming since the Arctic has seen the most dramatic effects attributed to warming of any region on Earth. Until strong evidence emerges that some other factor is forcing these dramatic mass losses, the sub-bullet value is TRUE. However, the evidence strength is demoted from "conclusive" to "strong" due to these concerns.
Brief summary of the issues: A complete description of the behavior of the Greenland ice sheet has to include two behaviors: ice mass loss--the change in the distribution and quantity of ice--and glacial dynamics--the change in the behavior of the ice. The dynamics data [such as Rignot and Kanagaratnam and Ekström] are strongly complementary to the mass balance data since glacial dynamics explains at least some of the mass loss and simultaneously acts as strong evidence of warming. Strong positive signatures of warming were found from both glacial dynamics studies and mass balance studies.
Summary of mass balance data:
Conclusion
This data constitutes strong evidence of north polar warming.
Sub-bullet value: TRUE
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