Global Warming: A Layman's Summary

Posted By Grim

I wouldn't normally write about Global Warming, which is a scholarly topic I am not qualified to discuss at length.  Since Jimbo did, though, and since he was mocked for it -- and since I've just finished an argument with an old friend on the subject this very day -- I figured I'd post my findings here. 

If it's something that interests you, here in the extended entry is my reading of the state of the argument.  I'm not a climatologist, nor indeed properly a scientist at all, but this is how it reads to a layman who takes an interest in the debate.  It treats scholarly papers on the subject from 1999 to the current day, and will give you a sense of what questions are still open, and what's being debated -- as well as links (when possible) or citations (when not), should any of you want to go and look them up for yourself.

It's in the extended entry for those interested.  If any of you are climatologists, I'd be happy to hear if you know of things my layman's survey has missed.

We'll start with two pieces in the mainstream press, which give a "landscape" view, before we hit the scholarly papers.  First, from the AP, an article that largely praises Gore's movie:  Scientists give two thumbs up to Gore's movie on global warming.

It's short, so you can read the whole thing.  The AP contacted 100 top climatologists, most of whom hadn't gone to see the movie.  The few who had rushed out to see it, however, were impressed.

What does that tell us?  Well, as we're about to see, there are several sides to the ongoing debate, and a number of them are deeply committed.  Gore's point of view was well-known going in.  Thus, the minority of scientists who had gone to see the movie right away were a self-selecting group, many of whom probably chose to go because they were already fans of the argument.

So, what we should probably read from this is that there is a minority of real scientists in this field that are true believers.  From their perspective, Gore is more or less correct.

Now, a second piece presenting the opposition. This is from Richard S. Lindzen, a professor at MIT -- again, a real scientist with real authority. He cites a number of serious methodological concerns with the data being used, and says that it's completely wrong to say that there is a consensus in the community of scientists, or that the debate is in any way closed. He is also hard on Gore's use of evidence, which he says is deeply flawed.

Again, to be fair, you'll want to read the whole thing. Dr. Lindzen is again a self-selecting group of one, so his opinion is just one opinion of one highly-qualified scientist, to balance against others.

Now that you've read those two pieces from the press, let's look at the scholarly side of the debate. To my reading, there are three real questions that are open, every one of which has serious implications for any policy decisions we might make:

A) Is the world experiencing a warming, or a cooling cycle?

B) Is it man-made, or is it a natural cycle?

C) How is the environment itself responding?

Dr. Lindzen, in the Bulletin of the American Meteorological Society (vol. 71 #3), presented the scholarly version of his skeptical argument. He points out that, while the concentration of carbon dioxide in atmospheric tests shows a consistent increase, it's not clear what that means. First of all, CO2 is only about 0.03% of any given atmosphere, so that even a doubling of the concentration (which is far beyond what is observed) would leave the atmosphere still 99.94% non-CO2. It is possible that CO2 levels are nevertheless important, even in these microscopic amounts, but it is not clear. It is also not clear (as to point C) how the oceans are absorbing CO2 levels, and therefore it isn't clear for models whether they will continue to do so, or stop doing so.

That point was the subject of two competing journal articles, which are not available online unless you want to pay for them. If you have access to EBSCOHost, you can probably dig them out for free; or visit a library, if you like.

The first is: Rahmstorf, Stefan and Andrey Ganopolski. "Long-Term Global Warming Scenarios Computed with an Efficient Coupled Climate Model." Climatic Change Vol. 43 No. 2, pp.353-367.

While they are believers in the process of environmental change, they state that their best current model shows that it is equally posible that the interplay of the oceans with the air and sea ice will cause CO2 circulation in the atmosphere to recover, or to collapse to far lower levels. In the latter case, "a substantial long-lasting cooling over the North Atlantic" is their prediction.

The second is: Cox, PM, et al. "Acceleration of global warming due to carbon-cycle feedbacks in a coupled-climate model." Nature 9 Nov 2000.

This article predicts an entirely different set of results from the idea of looking at these advanced models of how carbon and the ocean interact: it posits a feedback loop in which the ocean continues to sink CO2 levels until 2050, but then begins to act as a source of atmospheric CO2 levels. Thus, instead of a cooling period being equally likely with a warming period (and still within what the other survey called "uncertainty levels" for modeling), they state that they believe that global warming is certain and in fact will be greater than anticipated by any earlier survey.

Plattner, G-K, et al. "Feedback mechanisms and sensitivities of ocean carbon uptake under global warming." Tellus Series B, Vol. 53 No. 5, pp. 564-592.

This is a re-examination of the question of feedback loops from a year later. It attempts to account for observations that the ability of biospheres to handle CO2 absorption vary at different altitudes, which hadn't been accounted for in earlier models. It posits a need to re-think the data being provided by the Intergovernmental Panel on Climate Change, based on the fact that these data had not been earlier considered (the variations are noteworthy -- from 5-16%).

What does all this mean? It means that there's argument about point A -- whether we're seeing a warming or a cooling cycle, and about how certain we can be in making our prediction as to which it is.

On which topic: Weaver, Andrew J. and Claude Hillaire-Marcel. "Global Warming and the Next Ice Age." Science 16 Apr. 04.

Weaver and company are refuting other scientists (and "popular notions in the media") that global warming will lead to an ice age (e.g., the long-term cooling mentioned above). In order to do so, they explain that global warming (which they take as a given) will not affect North Atlantic ocean circulation in any important way.

That's a problem not just for the ice-age theories (if they are right) but also for the "stronger-hurricane" theories we heard after the 2004 hurricane season was so bad (and repeated after Katrina).

Here's one available online in full text (PDF). It's an interesting piece that looks at exactly when the increase in global temperatures happened in the last century, and finds it wasn't even, but rather concentrated in two twenty-year periods. The second, the article notes, is often ascribed to human carbon production; but the earlier one's cause is simply not clear, though it does not appear to be human use.

The author looks at several models for ocean rise/sea ice decrease, based on the earlier period, and tries to figure out what could have caused it based on those trends.

The problems for our understanding of the issue arising here are: if we can't account for why the earlier period showed such a spike, how can we be sure about what's causing this one? The causes may be a single cause, or there may be an additional complicating factor which has yet to be accounted for -- as the gentleman points out in his article, his data is problematic.

On the other hand, these folks are quite sure that we're already past the point of no return: Meehl, Gerald A. et al. "How Much More Global Warming and Sea Level Rise?" Science 18 Mar. 05.

They assert that, even if we'd stabilized carbon concentrations in the atmosphere in 2000, we would still observe an increase in global temperatures that will -- they assert -- result in a further 320% rise in sea levels. (I gather they mean, in addition to the increase in sea level that had already been predicted, as they can't mean that sea levels as a whole would rise by 320% -- most of the water in the world is already in the ocean).

Trenberth, Kevin. "Uncertainty in Hurricanes and Global Warming." Science 17 Jun. 05.

This is also on the subject of the unusual 2004 season. The author says it is probably attributable to atmospheric activity such as El Nino rather than global warming. He thinks global warming (because it affects sea surface temperatures and the amount of water vapor in the air in hurricane zones) will potentially have an effect on the development of tropical storms. However, he says, there is no way yet to say what the effect will be on hurricane numbers or their tracks.

I'll wind up by pointing out that this is my understanding: the scientists aren't in agreement on the three issues laid out above. Some believe global warming is not a real phenomenon; others believe it certainly is. Some who believe it is real also believe it can be arrested by human action; others believe it may not be much affected by human action; others belive it is due to human action, but is already too late. Some believe that the climate change is real, but could easily lead to cooling instead of warming; others believe warming is not only certain but being underpredicted. The reasons for the increase in temperatures observed are still being debated, as are the expected predictions for sea ice levels, hurricane formation, and all the rest.

I remain open to evidence, and I've here cited both true believers and skeptics, and a number of scientists who are honestly simply still searching for answers given the data in front of them. As they do, I remain open to new information and argument.

Again, I'm not an expert. This isn't my field. I am just a citizen, trying to sort out where the truth lies by looking to the writings of those who know more. If you've got something to add, feel free.

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Global Warming: A Layman's Summary

I wouldn't normally write about Global Warming, which is a scholarly topic I am not qualified to discuss at length.  Since Jimbo did, though, and since he was mocked for it -- and since I've just finished an argument with an old friend on the subject this very day -- I figured I'd post my findings here. 

If it's something that interests you, here in the extended entry is my reading of the state of the argument.  I'm not a climatologist, nor indeed properly a scientist at all, but this is how it reads to a layman who takes an interest in the debate.  It treats scholarly papers on the subject from 1999 to the current day, and will give you a sense of what questions are still open, and what's being debated -- as well as links (when possible) or citations (when not), should any of you want to go and look them up for yourself.

It's in the extended entry for those interested.  If any of you are climatologists, I'd be happy to hear if you know of things my layman's survey has missed.

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