April 8, 2009

Has the climate recently shifted?

“Has the climate recently shifted?” is the title of a just-published paper in Geophysical Research Letters by researchers Kyle Swanson and Anastasios Tsonis from the University of Wisconsin-Milwaukee. Their examination of this topic was undoubtedly prompted by the recent behavior of global temperature which shows that the rate of warming has dramatically slowed during the past 7-12 years.

Updating a methodology that they had previously developed and used to identify several changes in the climate state that occurred during the 20th century, Swanson and Tsonis examined the temperature data from recent years to see if another state change had taken place:

Here, a new and improved means to quantify the coupling between climate modes confirms that another synchronization of these modes, followed by an increase in coupling occurred in 2001/02. This suggests that a break in the global mean temperature trend from the consistent warming over the 1976/77–2001/02 period may have occurred.

In other words, the authors think that they have identified another in a string of break points that signal a change in the general state of the earth’s climate.

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March 5, 2009

Feedbacks and Climate Sensitivity

A week or two ago, Andrew Dessler and Steven Sherwood published a “Perspectives” (largely opinion) piece in Science magazine that argued that the water vapor feedback was unassailably strong and positive. This means that the warming from the increase in greenhouse gas concentrations leads to more water vapor in the atmosphere which leads to even more warming (water vapor is a strong greenhouse gas itself). This positive feedback results in roughly twice as much warming as would occur from anthropogenic greenhouse gas increases alone.

Dessler and Sherwood concluded:

There remain many uncertainties in our simulations of the climate, but evidence for the water vapor feedback—and the large future climate warming it implies—is now strong.

This conclusion has drawn a lot of attention within the community of researchers investigating the behavior of water vapor and the role of water feedback in climate change—and most of it has been highly critical.

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February 13, 2009

Subcommittee on Energy and Environment Testimony

On Thursday, February 12, 2009, Dr. Patrick J. Michaels provided testimony to the U.S. House of Representatives Subcommittee on Energy and Environment during their hearing “The Climate Crisis: National Security, Public Health, and Economic Threats.”

Dr. MIchaels’ general message was that the recent behavior of global temperatures is starting to push the (lower) bounds of climate models’ expectations of such behavior and that if the current slowdown in the rate of global warming continues for much longer, we must start to question the reliability of climate projections of the future state of our climate.

His complete written testimony in included below:

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December 3, 2008

Rethinking Observed Warming

The United Nations Climate Change Conference is underway this week in Poznan, Poland, and literally thousands of folks have convened and reinforced the notion that the buildup of greenhouse gases has caused substantial warming in recent decades and that left unchecked, the continued buildup will undoubtedly cause significant warming in the decades to come. Believe it or not, it is possible that aspects of the traditional greenhouse gas explanation could be largely wrong, and if you think we are crazy, let’s visit an article just published in the prestigious journal Climate Dynamics.

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February 21, 2008

Global Warming: Not So Fast

For more than 100 years, climate scientists have fully understood that if all else were held constant, an increase in the atmospheric concentration of carbon dioxide (CO2) would lead to an increase in the near-surface air temperatures. The problem becomes a lot more complicated in the real world when we consider that “all else” cannot be held constant and there are a lot more changes occurring at any one time than just the concentration of CO2. Once the temperature of the Earth starts inching upward, changes immediately occur to atmospheric moisture levels, cloud patterns, surface properties, and on and on. Some of these changes, like the additional moisture, amplify the warming and represent positive feedback mechanisms. Other consequences, like the development of more low clouds, would act to retard or even reverse the warming and represent negative feedbacks. Getting all the feedbacks correct is critical to predicting future conditions, and these feedbacks are simulated numerically in global climate general circulation models (GCMs). Herein lies a central component of the great debate — some GCMs predict relatively little warming for a doubling of CO2, and others predict substantial warming for the same change in atmospheric composition.

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August 14, 2007

The Iris Opens Again?

Back in 2001, Richard Lindzen and colleagues made quite a stir in the climate community when they published a paper in the Bulletin of the American Meteorological Society in which they describe having possibly identified an “adaptive infrared iris” that opens and closes to keep the earth’s temperature fairly steady even in light of increasing atmospheric carbon dioxide levels. It was proposed to work something like this—when the temperature in the tropical oceans begins to warm up, it causes in increase in the amount of low-level water clouds and an even greater decrease in total coverage of high-altitude ice clouds. Since ice clouds are net warmers (that is, they trap more outgoing longwave radiation (heat) than they reflect away incoming shortwave (solar) radiation) and water clouds are (generally) net coolers (reflecting back to space more incoming solar shortwave radiation than they absorb outgoing longwave radiation), more of the latter and a lot less of the former leads to a net cooling, and the temperatures of the tropical oceans decrease. However, cooler tropical ocean temperatures lead to less low-level (water) clouds and more high altitude ice clouds. This configuration tends to lead to a net radiation increase and to higher temperatures. And the cycle starts over again. Lindzen’s moniker “adaptive infrared iris” refers to the mechanism in which the tropical ice cloud cover opens and closes in response to tropical ocean temperatures to allow more heat to escape to space when the oceans are warm and less heat to escape to space when the oceans are relatively cool (much like the iris of an eye which opens and closes in response to varying light levels to try to maintain a constant level falling on the retina). Lindzen et al. proposed that the iris acts as a global thermostat that will keep the earth’s temperatures from rising very far even as atmospheric concentrations of greenhouse gases increase.

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November 27, 2006

Dimming Fights Drought?

A recent article in Geophysical Research Letters by Rutgers’ scientists Alan Robock and Haibin Li addresses the issue of global warming and reduced soil moisture levels in important agricultural areas. Every popular global warming presentation lays out the case that higher temperatures in the future will cause higher levels of evaporation that will overwhelm any changes in precipitation and force soil moisture levels to drop. Of course, crops will fail, we will have more frequent and severe droughts of longer duration, and it will have all been caused by elevated carbon dioxide (CO2) levels. You’ve heard the story a 1,000 times by now.

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November 2, 2006

Messy Models

The global warming scare comes largely, if not exclusively, from the outputs of numerical climate models. Some of the models are relatively simple in their design while other climate models are among the most sophisticated computer programs ever built. When the concentration of greenhouse gases is increased numerically, almost all models of climate show an increase in global temperature with the most warming occurring in the Northern Hemisphere’s highest latitudes. Predictions involving precipitation, drought, hurricanes, floods, changes in climate variability, and all the rest vary considerably from model to model. Many greenhouse advocates treat the 2 ×CO2 model simulations as predictions for the future with little regard for shortcomings in the way the models numerically represent the 1,000s of complex processes at work in the climate system.

The Intergovernmental Panel on Climate (IPCC) change warns in their Summary for Policymakers “models cannot yet simulate all aspects of climate (e.g., they still cannot account fully for the observed trend in the surface-troposphere temperature difference since 1979) and there a particular uncertainties associated with clouds and their interaction with radiation and aerosols.” Two articles have appeared in the scientific literature recently that further expose the weaknesses in the model simulations.

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August 24, 2006

A Sea Change in Global Warming?

For years now, we have been deluged with the news that the earth’s oceans are heating up as a result of changes in atmospheric composition resulting from the combustion of fossil fuels.

Typical of these was a 2005 story titled “Where’s The Heat? Think Deep Blue,” from United Press International, describing a recent paper in Science by NASA climate modeler James Hansen. UPI wrote that “Over the past ten years, the heat content of the ocean has grown dramatically.” This study covered more than just the ocean surface temperature, which can fluctuate considerably from year to year. Rather, by considering a much deeper layer (the top 2,500 feet), Hansen could actually calculate the increasing amount of heat that is being stored. According to UPI’s story, this provided “a match” with computer model projections of global warming.

The ocean is a huge flywheel that integrates and stores long-term climate changes. Consequently, when computer models are driven with ever-increasing atmospheric carbon dioxide, the deep oceans warm, warm, and warm. But it takes time to start up, just like a big pot of water heated by a small match. Once the process starts, though, nothing should be able to stop it.

That’s the current wisdom of our climate models, but like current wisdom on so many other aspects of life, nature has behaved differently.

Within weeks, a paper is going to appear in the refereed journal Geophysical Research Letters, by John Lyman of the National Oceanic and Atmospheric Administration, showing that, globally, the top 2500 feet of the ocean lost a tremendous amount of heat between from 2003 through 2005—about 20% of all the heat gained in the last half-century.

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January 31, 2006

Hot Tip: Post Misses the Point!

Juliet Eilperin’s latest headline in the Washington Post (January 29, 2006) about how global warming is destroying the earth was “Debate on Climate Shifts to Issue of Irreparable Change.” The Post, which has been news-editorializing this story for a couple of years now, featured her article above the fold in the top-right corner of the Sunday paper. Obviously they are exercised. Our response: cool it.
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