|
Note: This is a Text only archive. Go directly to the real forum.
If they did this to prisoners it would be considered torture.
- Click HERE to go to the original thread with graphics
banner
| If they did this to prisoners it would be considered torture.
- Click HERE to go to the original thread with graphics
|
| SDVT-2 |
So how did it become required classroom viewing?
Even climate change experts say many of the claims in Al Gore's film are wrong.
First it was his world history class. Then he saw it in his economics class. And his world issues class. And his environment class. In total, 18-year-old McKenzie, a Northern Ontario high schooler, says he has had the film An Inconvenient Truth shown to him by four different teachers this year.
"I really don't understand why they keep showing it," says McKenzie (his parents asked that his last name not be used). "I've spoken to the principal about it, and he said that teachers are instructed to present it as a debate. But every time we've seen it, well, one teacher said this is basically a two-sided debate, but this movie really gives you the best idea of what's going on."
:lol:
http://www.canada.com/nationalpost/...33-c904feb71047 |
|
|
| Ass Boil |
10 May 2006
Al Gore’s movie
by Eric Steig
Along with various Seattle business and community leaders, city planners and politicians, a large group of scientists from the University of Washington got a chance to preview the new film, An Inconvenient Truth, last week. The film is about Al Gore's efforts to educate the public about global warming, with the goal of creating the political will necessary for the United States to take the lead in efforts to lower global carbon emissions. It is an inspiring film, and is decidedly non-partisan in its outlook (though there are a few subtle references to the Bush administration's lack of leadership on this and other environmental issues).
Since Gore is rumored to be a fan of RealClimate, we thought it appropriate to give our first impressions.
Much of the footage in Inconvenient Truth is of Al Gore giving a slideshow on the science of global warming. Sound boring? Well, yes, a little. But it is a very good slide show, in the vein of Carl Sagan (lots of beautiful imagery, and some very slick graphics and digital animation). And it is interspersed with personal reflections from Gore that add a very nice human element. Gore in the classroom in 1968, listening to the great geochemist Roger Revelle describe the first few years of data on carbon dioxide increases in the atmosphere. Gore on the family farm, talking about his father's tobacco business, and how he shut it down when his daughter (Al Gore's sister) got lung cancer. Gore on the campaign trail, and his disappointment at the Supreme Court decision. This isn't the "wooden" Gore of the 2000 campgain; he is clearly in his element here, talking about something he has cared deeply about for over 30 years.
How well does the film handle the science? Admirably, I thought. It is remarkably up to date, with reference to some of the very latest research. Discussion of recent changes in Antarctica and Greenland are expertly laid out. He also does a very good job in talking about the relationship between sea surface temperature and hurricane intensity. As one might expect, he uses the Katrina disaster to underscore the point that climate change may have serious impacts on society, but he doesn't highlight the connection any more than is appropriate (see our post on this, here).
There are a few scientific errors that are important in the film. At one point Gore claims that you can see the aerosol concentrations in Antarctic ice cores change "in just two years", due to the U.S. Clean Air Act. You can't see dust and aerosols at all in Antarctic cores -- not with the naked eye -- and I'm skeptical you can definitively point to the influence of the Clean Air Act. I was left wondering whether Gore got this notion, and I hope he'll correct it in future versions of his slideshow. Another complaint is the juxtaposition of an image relating to CO2 emissions and an image illustrating invasive plant species. This is misleading; the problem of invasive species is predominantly due to land use change and importation, not to "global warming". Still, these are rather minor errors. It is true that the effect of reduced leaded gasoline use in the U.S. does clearly show up in Greenland ice cores; and it is also certainly true that climate change could exacerbate the problem of invasive species.
Several of my colleagues complained that a more significant error is Gore's use of the long ice core records of CO2 and temperature (from oxygen isotope measurements) in Antarctic ice cores to illustrate the correlation between the two. The complaint is that the correlation is somewhat misleading, because a number of other climate forcings besides CO2 contribute to the change in Antarctic temperature between glacial and interglacial climate. Simply extrapolating this correlation forward in time puts the temperature in 2100 A.D. somewhere upwards of 10 C warmer than present -- rather at the extreme end of the vast majority of projections (as we have discussed here). However, I don't really agree with my colleagues' criticism on this point. Gore is careful not to state what the temperature/CO2 scaling is. He is making a qualitative point, which is entirely accurate. The fact is that it would be difficult or impossible to explain past changes in temperature during the ice age cycles without CO2 changes (as we have discussed here). In that sense, the ice core CO2-temperature correlation remains an appropriate demonstration of the influence of CO2 on climate.
For the most part, I think Gore gets the science right, just as he did in Earth in the Balance. The small errors don't detract from Gore's main point, which is that we in the United States have the technological and institutional ability to have a significant impact on the future trajectory of climate change. This is not entirely a scientific issue -- indeed, Gore repeatedly makes the point that it is a moral issue -- but Gore draws heavily on Pacala and Socolow's recent work to show that the technology is there (see Science 305, p. 968 Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies).
I'll admit that I have been a bit of a skeptic about our ability to take any substantive action, especially here in the U.S.
Gore's aim is to change that viewpoint, and the colleagues I saw the movie with all seem to agree that he is successful.
In short: this film is worth seeing. It opens in early June.
http://www.realclimate.org/index.ph...al-gores-movie/ |
|
|
| Ass Boil |
27 Apr 2007
The lag between temperature and CO2. (Gore’s got it right.)
Eric Steig
When I give talks about climate change, the question that comes up most frequently is this: “Doesn’t the relationship between CO2 and temperature in the ice core record show that temperature drives CO2, not the other way round?"
On the face of it, it sounds like a reasonable question. It is no surprise that it comes up because it is one of the most popular claims made by the global warming deniers. It got a particularly high profile airing a couple of weeks ago, when congressman Joe Barton brought it up to try to discredit Al Gore’s congressional testimony. Barton said:
In your movie, you display a timeline of temperature and compared to CO2 levels over a 600,000-year period as reconstructed from ice core samples. You indicate that this is conclusive proof of the link of increased CO2 emissions and global warming. A closer examination of these facts reveals something entirely different. I have an article from Science magazine which I will put into the record at the appropriate time that explains that historically, a rise in CO2 concentrations did not precede a rise in temperatures, but actually lagged temperature by 200 to 1,000 years. CO2 levels went up after the temperature rose. The temperature appears to drive CO2, not vice versa. On this point, Mr. Vice President, you’re not just off a little. You’re totally wrong.
Of course, those who've been paying attention will recognize that Gore is not wrong at all. This subject has been very well addressed in numerous places. Indeed, guest contributor Jeff Severinghaus addressed this in one of our very first RealClimate posts, way back in 2004. Still, the question does keep coming up, and Jeff recently received a letter asking about this. His exchange with the letter writer is reproduced in full at the end of this post. Below is my own take on the subject.
First of all, saying "historically" is misleading, because Barton is actually talking about CO2 changes on very long (glacial-interglacial) timescales. On historical timescales, CO2 has definitely led, not lagged, temperature. But in any case, it doesn't really matter for the problem at hand (global warming). We know why CO2 is increasing now, and the direct radiative effects of CO2 on climate have been known for more than 100 years. In the absence of human intervention CO2 does rise and fall over time, due to exchanges of carbon among the biosphere, atmosphere, and ocean and, on the very longest timescales, the lithosphere (i.e. rocks, oil reservoirs, coal, carbonate rocks). The rates of those exchanges are now being completely overwhelmed by the rate at which we are extracting carbon from the latter set of reservoirs and converting it to atmospheric CO2. No discovery made with ice cores is going to change those basic facts.
Second, the idea that there might be a lag of CO2 concentrations behind temperature change (during glacial-interglacial climate changes) is hardly new to the climate science community. Indeed, Claude Lorius, Jim Hansen and others essentially predicted this finding fully 17 years ago, in a landmark paper that addressed the cause of temperature change observed in Antarctic ice core records, well before the data showed that CO2 might lag temperature. In that paper (Lorius et al., 1990), they say that:
changes in the CO2 and CH4 content have played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing
What is being talked about here is influence of the seasonal radiative forcing change from the earth's wobble around the sun (the well established Milankovitch theory of ice ages), combined with the positive feedback of ice sheet albedo (less ice = less reflection of sunlight = warmer temperatures) and greenhouse gas concentrations (higher temperatures lead to more CO2 leads to warmer temperatures). Thus, both CO2 and ice volume should lag temperature somewhat, depending on the characteristic response times of these different components of the climate system. Ice volume should lag temperature by about 10,000 years, due to the relatively long time period required to grow or shrink ice sheets. CO2 might well be expected to lag temperature by about 1000 years, which is the timescale we expect from changes in ocean circulation and the strength of the "carbon pump" (i.e. marine biological photosynthesis) that transfers carbon from the atmosphere to the deep ocean.
Several recent papers have indeed established that there is lag of CO2 behind temperature. We don't really know the magnitude of that lag as well as Barton implies we do, because it is very challenging to put CO2 records from ice cores on the same timescale as temperature records from those same ice cores, due to the time delay in trapping the atmosphere as the snow is compressed into ice (the ice at any time will always be younger older than the gas bubbles it encloses, and the age difference is inherently uncertain). Still, the best published calculations do show values similar to those quoted by Barton (presumably, taken from this paper by Monnin et al. (2001), or this one by Caillon et al. (2003)). But the calculations can only be done well when the temperature change is large, notably at glacial terminations (the gradual change from cold glacial climate to warm interglacial climate). Importantly, it takes more than 5000 years for this change to occur, of which the lag is only a small fraction (indeed, one recently submitted paper I'm aware of suggests that the lag is even less than 200 years). So it is not as if the temperature increase has already ended when CO2 starts to rise. Rather, they go very much hand in hand, with the temperature continuing to rise as the the CO2 goes up. In other words, CO2 acts as an amplifier, just as Lorius, Hansen and colleagues suggested.
Now, it there is a minor criticism one might level at Gore for his treatment of this subject in the film (as we previously pointed out in our review). As it turns out though, correcting this would actually further strengthen Gore's case, rather than weakening it. Here's why:
The record of temperature shown in the ice core is not a global record. It is a record of local Antarctic temperature change. The rest of the globe does indeed parallel the polar changes closely, but the global mean temperature changes are smaller. While we don't know precisely why the CO2 changes occur on long timescales, (the mechanisms are well understood; the details are not), we do know that explaining the magnitude of global temperature change requires including CO2. This is a critical point. We cannot explain the temperature observations without CO2. But CO2 does not explain all of the change, and the relationship between temperature and CO2 is therefore by no means linear. That is, a given amount of CO2 increase as measured in the ice cores need not necessarily correspond with a certain amount of temperature increase. Gore shows the strong parallel relationship between the temperature and CO2 data from the ice cores, and then illustrates where the CO2 is now (384 ppm), leaving the viewer's eye to extrapolate the temperature curve upwards in parallel with the rising CO2. Gore doesn't actually make the mistake of drawing the temperature curve, but the implication is obvious: temperatures are going to go up a lot. But as illustrated in the figure below, simply extrapolating this correlation forward in time puts the Antarctic temperature in the near future somewhere upwards of 10 degrees Celsius warmer than present -- rather at the extreme end of the vast majority of projections (as we have discussed here).
Global average temperature is lower during glacial periods for two primary reasons:
1) there was only about 190 ppm CO2 in the atmosphere, and other major greenhouse gases (CH4 and N2O) were also lower
2) the earth surface was more reflective, due to the presence of lots of ice and snow on land, and lots more sea ice than today (that is, the albedo was higher).
As very nicely discussed by Jim Hansen in his recent Scientific American article, the second of these two influences is the larger, accounting for about 2/3 of the total radiative forcing. CO2 and other greenhouse gases account for the other 1/3. Again, this was all pretty well known in 1990, at the time of the Lorius et al. paper cited above.
What Gore should have done is extrapolated the temperature curve according this the appropriate scaling -- with CO2 accounting for about 1/3 of the total change -- instead of letting the audience do it by eye. Had he done so, he would have drawn a line that went up only 1/3 of the distance implied by the simple correlation with CO2 shown by the ice core record. This would have left the impression that equilibrium warming of Antarctica due to doubled CO2 concentrations should be about 3 °C, in very good agreement with what is predicted by the state-of-the-art climate models. (It is to be noted that the same models predict a significant delay until equilibrium is reached, due to the large heat capacity of the Southern ocean. This is in very good agreement with the data, which show very modest warming over Antarctica in the last 100 years). Then, if you scale the Antarctic temperature change to a global temperature change, then the global climate sensitivity to a doubling of CO2 becomes 2-3 degrees C, perfectly in line with the climate sensitivity given by IPCC (and known from Arrhenius's calculations more than 100 years ago).
In summary, the ice core data in no way contradict our understanding of the relationship between CO2 and temperature, and there is nothing fundamentally wrong with what Gore says in the film. Indeed, Gore could have used the ice core data to make an additional and stronger point, which is that these data provide a nice independent test of climate sensitivity, which gives a result in excellent agreement with results from models.
A final point. In Barton's criticism of Gore he also points out that CO2 has sometimes been much higher than it is at present. That is true. CO2 may have reached levels of 1000 parts per million (ppm) -- perhaps much higher -- at times in the distant geological past (e.g. the Eocene, about 55 million years ago). What Barton doesn't bother to mention is that the earth was much much warmer at such times. In any case, more relevant is that CO2 has not gone above about 290 ppm any time in the last 650,000 years (at least), until the most recent increase, which is unequivocally due to human activities.
http://www.realclimate.org/index.ph...n-temp-and-co2/ |
|
|
| Ass Boil |
Scientists OK Gore's movie for accuracy
Posted 6/27/2006 5:54 PM ET
By Seth Borenstein, Associated Press
The nation's top climate scientists are giving An Inconvenient Truth, Al Gore's documentary on global warming, five stars for accuracy.
The former vice president's movie — replete with the prospect of a flooded New York City, an inundated Florida, more and nastier hurricanes, worsening droughts, retreating glaciers and disappearing ice sheets — mostly got the science right, said all 19 climate scientists who had seen the movie or read the book and answered questions from The Associated Press.
The AP contacted more than 100 top climate researchers by e-mail and phone for their opinion. Among those contacted were vocal skeptics of climate change theory. Most scientists had not seen the movie, which is in limited release, or read the book.
But those who have seen it had the same general impression: Gore conveyed the science correctly; the world is getting hotter and it is a manmade catastrophe-in-the-making caused by the burning of fossil fuels.
"Excellent," said William Schlesinger, dean of the Nicholas School of Environment and Earth Sciences at Duke University. "He got all the important material and got it right."
Robert Corell, chairman of the worldwide Arctic Climate Impact Assessment group of scientists, read the book and saw Gore give the slideshow presentation that is woven throughout the documentary.
"I sat there and I'm amazed at how thorough and accurate," Corell said. "After the presentation I said, 'Al, I'm absolutely blown away. There's a lot of details you could get wrong.' ... I could find no error."
Gore, in an interview with the AP, said he wasn't surprised "because I took a lot of care to try to make sure the science was right."
The tiny errors scientists found weren't a big deal, "far, far fewer and less significant than the shortcoming in speeches by the typical politician explaining an issue," said Michael MacCracken, who used to be in charge of the nation's global warming effects program and is now chief scientist at the Climate Institute in Washington.
One concern was about the connection between hurricanes and global warming. That is a subject of a heated debate in the science community. Gore cited five recent scientific studies to support his view.
"I thought the use of imagery from Hurricane Katrina was inappropriate and unnecessary in this regard, as there are plenty of disturbing impacts associated with global warming for which there is much greater scientific consensus," said Brian Soden, a University of Miami professor of meteorology and oceanography.
Some scientists said Gore confused his ice sheets when he said the effect of the Clean Air Act is noticeable in the Antarctic ice core; it is the Greenland ice core. Others thought Gore oversimplified the causal-link between the key greenhouse gas carbon dioxide and rising temperatures.
While some non-scientists could be depressed by the dire disaster-laden warmer world scenario that Gore laid out, one top researcher thought it was too optimistic. Tom Wigley, senior scientist at the National Center for Atmospheric Research, thought the former vice president sugarcoated the problem by saying that with already-available technologies and changes in habit — such as changing light bulbs — the world could help slow or stop global warming.
While more than 1 million people have seen the movie since it opened in May, that does not include Washington's top science decision makers. President Bush said he won't see it. The heads of the Environmental Protection Agency and NASA haven't seen it, and the president's science adviser said the movie is on his to-see list.
"They are quite literally afraid to know the truth," Gore said. "Because if you accept the truth of what the scientific community is saying, it gives you a moral imperative to start to rein in the 70 million tons of global warming pollution that human civilization is putting into the atmosphere every day."
As far as the movie's entertainment value, Scripps Institution geosciences professor Jeff Severinghaus summed it up: "My wife fell asleep. Of course, I was on the edge of my chair."
Copyright 2006 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Find this article at:
http://www.usatoday.com/tech/scienc...nce-truth_x.htm
|
|
|
|
|
|
