An Absorbing Collision

CO₂-collision/absorbtionBelief in global warming, and especially the causes of GW (if one believes the data) depend crucially on modeling. The physics of atmospheric gases-solar radiation interactions, especially those involving carbon-dioxide molecules, is of major importance because the increase of CO₂ is often quoted as a correlate to warming. The story is basically that CO₂ absorbs some of the infrared radiation (IR) streaming to the earth from the sun, and reflects the rest back.

Just how much is absorbed? The answer to this question is a crucial one. Until recently, the basic physics of light absorption by gas molecules, though pretty well understood, doesn't get the amounts of IR absorption correct for atmospheric CO₂. Is this a failure of physics, or the model used?

Get serious. Of course it's not the physics. To paraphrase, it's the model , stupid. Physicists decide what goes into a model, and then the physics (in the form of fundamental laws) takes over, yielding the model prediction.

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Hurricane Prediction, Pt. 2 - Path and Intensity

Projections for Hurricane Dean (NOAA)This post continues the discussion of hurricane prediction begun in my recent post.  There I described efforts at predicting hurricanes before they actually start, and the use of correlates such as el niño and sand in the Sahara.

What about predictions once the hurricanes are on the scene? The recent news surrounding the potential path of Hurricane Dean, and the predicted intensity, are different types of models.

There's an informative article today by Matt McGrath for BBC News that discusses the issues surrounding these predictions. (See The Science of Hurricane Prediction ) Of interest is the fact that it easier to predict the ultimate path of faster-moving hurricanes. In effect, when hurricanes "hang around" too long, their motion can be affected by many other factors - throwing off the model predictions. 

The BBC News site has a number of clever animations, including an animated guide to how hurricanes form. This is a nice applet - one of a set of applets for many natural disasters, including earthquakes, tsunamis, tornadoes, and volcanoes.

Saharan Sand & Hurricane Prediction

I have written before about modeling earthquakes and hurricanes - two phenomena are often not covered in homeowners insurance because they are Acts of God. There is still a long way to go before these are understood to the satisfaction of a predominance of scientists.

But what about prediction? With hurricane season about to start in earnest in the Atlantic, it has been pretty quiet. How are hurricanes predicted, and how good are these predictions?

El Niño events and hurricanes are highly correlated, and hence the Niño is part of every hurricane forecasters toolkit/ There has been a lot of publicity of late indicating a strong correlation between Saharan sand storms and hurricane activity, suggesting that sand activity would complement El Nino as a predictor.

While no one would dispute the value of another correlate for hurricane activity, I did notice the typical media confusion between understanding what was going on, and what was purely a prediction based on a correlation. I was just about to write one of my typical rants when I came across a blog that already took the media to task back in 2006. Written by Daniel Collins from UW-Madison on his Down To Earth blog, the post title says it all:

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How to read a REAL Climate Modeling article

Diagram of General Circulatin ModelBolstered by the anti-climate-modeling stance of Michael Crichton, there are many out there who claim that climate modeling that predicts global warming is somehow "bad science." I'm not sure many of these folks have ever read a real climate modeling paper (or any who believe that climate change is occurring, for that matter)

It is instructive to try to wade through a serious paper that points out the difficulties of modeling on the one hand, but also presents very confident predictions of the model described in the paper..

By chance I recently came across a paper written almost 2 years ago by Jian Yuan, Qiang Fu (Department of Atmospheric Sciences, University of Washington) and Norman McFarlane (Canadian Centre for Climate Modeling and Analysis, Victoria, British Columbia). The name of the article is forbidding: Tests and improvements of GCM cloud parameterizations using the CCCMA SCM with the SHEBA data set.

(Note: GCM is General Circulation Model, or Global Climate Model - the bellwether of climate modeling)

The article describes the wide variability of different models of the Arctic, and how the authors re-formulated cloud interactions, yielding a model whose output is much closer to actual recorded data.

For the uninitiated, trying to read this type of paper seems impossible. You can get a lot from it, though, by reading the abstract, intro, and conclusion. (This is something I do in the Chaos and Fractals course - i.e. have students read and dense papers in areas outside of their majors - an essential activity for all scientists).

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Hot Baseball News - Say Hey to Global Warming?

Whether or not baseball is still America's Game has been debated for a long time.  For some, its often-glacial pace can't compete with the speed and physical intensity of the other major sports.

But for others the glacial pace is both comforting and a description of their rate of acceptance of the reality of climate change.

Recently, Sports Illustrated devoted a sizeable part of an issue to the effects of global warming on sports. From Golf courses to ski slopes, the article was a thorough summary of potential changes to sports because of the possible loss of outdoor venues. (See Going, Going Green by Alexander Wolff). A lot of doomsday scenarios to be sure - but some chilling images nonetheless. None more so than a sidebar on The Catch - Willie Mays' famous steal of Vic Wertz's shot to center field in the 1954 World Series between the NY Giants and Cleveland.

The story is that with global warming, average temperatures have risen just enough to make Mays' catch much harder, and quite possibly impossible, even for Willie. This is because the higher temperatures produce air that is less dense, allowing the ball to travel just a little bit farther then it would have otherwise. Compared to average temps of 76° in 1954, today's average temp of slightly more than 77° would give Wertz's fly ball an extra two inches of loft. Would Mays still get the ball, or would it hit the tip of the glove's webbing and bounce off? Would the Giants go on to sweep the Indians?

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Modeling Acts of God, Part 1

Hurricane structure. Click to enlarge.

This post is the first in a series of the state of modeling very powerful, nasty natural phenomena such as hurricanes, earthquakes, and tsunami.

Depending on where you live you may have trouble acquiring or affording insurance protection form these so-called "acts of God. "  Whatever these AOG's might be, they are often home- and life-threatening.  Can these AOG's be modeled successfully, i.e. how well are they understood and can their generation, properties, and behavior be predicted with any accuracy?

Along with the understanding and prediction provided by standard models for these event, it is natural to wonder how global warming contributes to these phenomena. Do models for these AOG's compensate for GW's effect? This is a very pressing question. Anecdotally, many claim that the events are both more frequent and more severe, with natural tendency to assign blame to global warming.

Consider hurricanes. Hurricanes are pretty well "understood" in terms of how they start and move. Proto-hurricanes start as small tropical vortices , which themselves originate because of rotational effects of the earth on atmospheric gases. Kerry Emanuel, Professor of atmospheric sciences at MIT explains this in Hurricanes: Tempests in a Greenhouse:

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One Degree of Separation - Global Hot Air

Sterling Hot-Air Engine. Click to enlarge.The world, and especially all of blogville has exploded with the release of the IPCC's executive summary of its 2007 Climate Change: The Physical Basis. A web search for anything to do with global warming seems to yield just as many blogs that talk about the "myths" of global warming (e.g. see JunkScience) as there are "myths about myths" about global warming (e.g. see The Environmental Defense Fund site). How can anyone navigate through this stream of flotsam/jetsam? How do these blogs do anything but attract those who already believe in that point of view, or are leaning heavily that way?

Not even political persuasion is a good predictor of what you'll find out there. For example, read Facts and Myths about Global Warming: A Conservative Perspective at the The Green Elephant site. Green Elephant being the Republicans for Environmental Protection, of course.

Then there is the godfather of the anti-warming crowd - none other than the king of science fact/fiction media success - Michael Crichton (see my previous post on Crichton's role in the GW debate). His recent lecture The Impossibility of Prediction is a good example of why Crichton is listened-to and often quoted, especially by members of the Bush administration who,

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Coping with Chaotic Climate Models

Model prediction of Arctic sea ice loss - 2000 (L) vs. 2040 (R). From BBC news. Click to Enlarge.Now that the IPCC has released the summary of it's upcoming study report Climate Change 2007: The Physical Science Basis , strongly stating that global warming is man-made, it is still important for scientists to clearly enumerate any issues surrounding the accuracy and reliability of their models.

Because if they don't, global warming deniers, or those who believe that we need still more time for convincing proof will focus on the slightest inaccuracy in a model's prediction in classic red herring fashion. (In a way similar to anti-evolutionists, they will neglect the hundreds of accurate predictions and claim that the one that doesn't quite fit calls for total abandonment of a theory.)

Climate models are by their very nature prone to chaotic behavior. This behavior must be accounted for when using climate models for any type of prediction.  An excellent article on how chaotic models are handled has been provided recently by Cecilia Bitz of the Univ. of Washington. In her Real Climate article Arctic Sea Ice decline in the 21st Century, Bitz describes work she did with colleagues Marika Holland and Bruno Tremblay, which culminated in a paper for the Dec. 2006 Geophysical Research Letters. I want to focus on two aspects of Bitz's commentary: the presence of chaos in the climate models, and the overall accuracy of the modeling process. Bitz recounts:

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Breaking the Ice Shelf - Why Hide the Crack?

The ice shelf breaks away. Click to enlarge.

In December 2006 it was widely reported that the 25.5-square-mile Ayles ice-shelf broke free from Ellesmere island, some 500 miles south of the North Pole. (See the National Geographic report for more details.)

This event actually occurred in 2005 when it had been observed by satellite images (click here for animations of the event), but, according to Luke Copeland of the University of Ottawa Global Laboratory for Cryospheric Research, the information was not released until the reasons for the split could be determined.

Not surprisingly, Copeland and colleagues found that the event, which was sizeable enough to register on earthquake monitors 155 miles away, is consistent with global warming.

I understand that scientists should be as deliberate as possible in doing their research, and circumspect (or silent) about their work until all of the essential methodology of good scientific research prior to publishing are carried out.

But I find it incredibly surprising that the news of the ice-shelf breaking off was held back from publication for almost one-and-a-half years! After all, the ice-shelf cracking is incontrovertible data that is not in question. More important, it is essential data for all inhabitants of this planet.

Why was the news withheld?

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A Jolting Message: Hemingway's Snow and Climate Change

Kilimanjaro, then and now. Click to enlarge.I have remarked before on the ever-increasing media coverage given to global warming. As more and more scientific evidence comes in about the effects of global warming (see my recent post On the Increase in Greenland Ice Loss), the facts, interpretations, scientific theories, and political reactions to climate change are incredibly varied in the face of almost overwhelming evidence. Making sense of what is really happening, and how we should react, calls for insightful commentary from expert sources.

One such source is an article by Doug Macdougall of the Scripps Institution of Oceanography titled Jolting Messages on Climate Change. (The Chronicle, April 2006). In addition to his clear enunciation of global climate change facts and a strong call for "jolting messages" that will move "politicians and the public into effective action," Macdougall reviews five books about climate change published in 2005 and 2006:

• Climate Crash: Abrupt Climate Change and What it Means for our Future, by John D. Cox
• Field Notes From a Catastrophe: Man, Nature, and Climate Change, by Elizabeth Kolbert
• Kicking the Carbon Habit: Global Warming and the Case for Renewable and Nuclear Energy by William Sweet
• The Weather Makers: The History and Future Impact of Climate Change, by Tim Flannery
• The Winds of Change: Climate, Weather, and the Destruction of Civilizations, by Eugene Linden

According to Macdougall, each of these books have strong points. I encourage you to read Macdougall's reviews, which are very even-handed. Some of the authors are more pessimistic than the others in terms of what can be done (via science, engineering, politics), but all agree on the scope of the problem. Most of the books do take on the sudden climate changes that were first observed in studies of the Greenland ice sheet.

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