The Real Greenhouse Effect
The George C. Marshall Institute has just released a published manuscript of a speech given on May 17 by Dr. Richard Lindzen, the Alfred P. Sloan Professor of Meteorology at M.I.T. The speech, Climate Forecasting: When Models are Qualitatively Wrong, argues that climate models are wanting compared to real world data.
Dr. Lindzen begins by discussing the “real greenhouse effect.” According to him, the explanation as presented to the public of what constitutes the greenhouse effect is misleading. The UN Intergovernmental Panel on Climate Change explains, for instance, that sunlight passes through the atmosphere to illuminate the earths surface. Some sunlight is reflected, but much is absorbed. Greenhouse gases, primarily clouds and water vapor, act like a blanket that prevents heat escaping from the earth, and the earth gets warmer.
In reality, said Lindzen, “Infrared gases, not the surface, are what send the radiation back to space. Indeed, space cannot see the surface, by and large, except at the poles. Instead, space sees some level about five kilometers up, in the troposphere.” This level is known as the “characteristic emission level” (CEL). A doubling of CO2 would cause the CEL to move out about 150 meters, says Lindzen. “But because the temperature of the air decreases with height, this new level is colder. And because it is colder, it emits less radiation to space. That creates an imbalance, and the greenhouse effect requires that balance be reestablished. Essentially, to make up for raising the CEL 150 meters, the temperature has to increase about 1 degree C at the CEL.”
“How this impacts earths surface is not at all clear,” said Lindzen. Events at five kilometers are connected to events at the surface by processes such as motions of the air so it is thought that the surface will follow suit. “That gives you a 1 degree C increase at the surfacemaybe.”
So where do the estimates of warming from 1.5 to 4.5 degrees C come from? Through feedbacks that amplify the initial warming caused by increases in greenhouse gases. A positive feedback is one that amplifies warming and a negative feedback is one that dampens it. The models show that as temperature warms the air holds more water vapor, the principal greenhouse gas. This is a positive feedback that amplifies warming.
The problem with the models is their use of average cloud cover or average humidity. “We know that thinking in terms of averages is not appropriate. Rather, observations show very dry air in some regions, very moist air in others, and very sharp boundaries between them,” said Lindzen.
Looking at how these moist and dry regions react to changes in atmospheric CO2 is the key to understanding global warming, according to Lindzen. He has found “that the area of cloudy regions went down 15 percent for every 1 degree C increase in temperature,” a negative feedback.
Lindzen concludes, “If you calculate the impact of this negative feedback on the globe as a whole, the impact is larger by a factor of four than the total positive feedbacks in the most sensitive current models. What this means is that even if there were a factor-of-five uncertainty in what weve seen which is a large uncertainty the models that predict that doubling carbon dioxide would increase temperature 1.5 degrees to 4 degrees C, would now predict an increase of 0.6 degrees to 1.5 degrees C.”
CO2 and Biodiversity
An editorial by the Center for the Study of Carbon Dioxide and Global Change argues that the rising concentration of atmospheric CO2 increases biodiversity. The article cites two studies, one in Nature (406) and the other in the Annual Review of Ecology and Sytemics (30). The Nature study found that, “At continental scales, the diversity of plants and animals usually increases monotonically with productivity.” The ARES article found that, “At larger spatial scales it has been observed that diversity tends to increase linearly with productivity.”
This means that biodiversity increases at the same rate as plant productivity. It has been shown repeatedly in scientific studies that higher levels of atmospheric CO2 enhance plant productivity. According to the article, “Pulling these two observations together, we conclude that one of the best things we could possibly do to preserve the biodiversity or species richness of the planet is let the carbon dioxide content of the air continue to rise, rejecting all overt attempts to curtail anthropogenic CO2 emission via Kyoto-style interventions.” See www.co2science.org.
Announcements
- The George C. Marshall Institute has published a study, Climate Models and the National Assessment, by Dr. David Legates, Associate Professor of Climatology in the Center for Climatic Research, University of Delaware. Legates criticizes the National Assessments misuse of Global Climate Models to predict regional impacts of global warming. To get a copy of the study, contact Jeff Salmon or Mark Herlong at (202) 296-9655. A press release may be found at www.marshall.org.
- The Center for the Study of American Business at Washington University in St. Louis has published a monograph, Applying the Precautionary Principle to Global Warming, by Indur M. Goklany. Goklany argues that “the so-called precautionary principle often invoked to justify a greenhouse gas control policy must consider not only risks that such a policy might reduce but also risks that it might generate.” For more information, contact Robert Batterson at (314) 935-5676. The CSAB web sites address is www.csab.wustl.edu.