Thousands of websites present the usual view of global warming claiming that greenhouse gases are increasing in atmospheric concentration, this is causing the planet to warm, and if we don’t act immediately, an endless number of calamities are certain to become reality. These sites then make every effort to make you believe that much of the problem can be placed at the feet of President Bush, Vice President Cheney, and just about anyone associated with the gas, oil, and coal companies in the United States. There are mentions here and there of contributions from other countries, but you will constantly be reminded that the United States is the largest emitter of greenhouse gases, that the relatively small population of the USA has an immoral per capita emission level, and that no one on the planet should feel more guilty about global warming than folks who voted for the current administration.

To be fair, there have been news reports recently that China’s total emission of carbon dioxide (CO2) has surpassed the emission from the United States. Along these lines, an important article has appeared in Geophysical Research Letters that shows China is now our global leader in CO2 emission, which is certainly newsworthy, but other results presented in their article may be received as bad news by the global warming alarmists. The research was conducted by three scientists at the University of Maryland, the Oak Ridge National Laboratory, and Austria’s International Institute for Applied Systems Analysis; a portion of the research was funded by the U.S. Department of Energy, Office of Science, Biological and Environmental Research Programs.

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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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The American Geophysical Union (AGU) recently released its new and improved “position statement” on global warming. Andy Revkin of the New York Times featured the AGU’s release on this DotEarth blog site and asked AGU members to chime in on their opinions of the statement that was developed by the AGU’s ruling Council. While there were definitely members who expressed dismay at the position statement, a majority of commentors gave it their hearty endorsement. Apparently, most of the endorsers have not given a very in depth consideration of all that is contained in the AGU’s statement, for otherwise, (we would hope anyway) that they would have been a bit more reserved.

For instance, the AGU’s position statement includes the following sentence: “If this 2 degrees Celsius warming [above 19th century levels] is to be avoided, then our net annual emissions of carbon dioxide must be reduced by more than 50 percent within this century.” This is akin to stating “If pigs had wings, they could fly.” Sure, you could endorse the statement, but to do so would seem a bit foolish. First off, pigs don’t have wings, and it would take nothing short of a miracle for them to acquire them, and secondly, even if they had wings, it is not guaranteed that they could fly. The most pig-shaped bird we can think of—the penguin which is large and rotund and flopping around on its belly a lot of the time—has wings, but can’t fly. Thus even if the impossibility of pigs sporting wings was overcome, it wouldn’t insure a successful flight.

The same is true of the AGU’s statement about a 50% CO2 reduction this century and its impacts on global temperature. First off, it will take nothing short of a miracle for the 50% reduction to take place, and secondly, it probably wouldn’t stop the temperature from rising 2ºC above “natural” levels. Endorse it if you want, but it doesn’t reflect well on your scientific reasoning skills.

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The recent wildfires in California have certainly provided an opportunity for the greenhouse crusade to further claim that global warming is already increasing fire frequency, duration, and intensity all over the planet. In the midst of the disaster in California, Nevada Democrat and Senate Majority Leader Harry Reid told reporters that “One reason why we have the fires in California is global warming.” However, when pressed by astonished reporters on whether he really believed global warming caused the fires, he appeared to back away from his comments, saying there are many factors that contributed to the disaster. Since then, literally hundreds of newspaper articles appeared throughout the country reinforcing the idea that emissions of greenhouse gases have warmed the earth, dried the forests, and made fires a lot worse.

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Climate scientists have known for many years that the energy output from the Sun varies and believe it or not, when the Sun is putting out more energy, the Earth heats up and when the Sun cools down, so does the Earth. What appears to be so simple is actually much more complex as the Sun can vary its output differentially in the various portions of the electromagnetic spectrum. For example, the Sun can actually increase its production of gamma rays while decreasing the level of infrared emission, and these patterns of energy output can reveal themselves quite differently in terms of response of Earth’s climate.

Nonetheless, over the past century, the correlation between solar irradiance (in Watts per square meter) and the planetary temperature anomaly (in °C) is highly statistically significant; the Pearson product-moment correlation coefficient is 0.51 and is beyond the 0.99 level of statistical confidence (see below). The line on the plot basically represents a simple statistical linear “model” that predicts the planetary temperature anomaly given a specific output level of the Sun. For every year we could examine the difference between the observed temperature anomaly and the predicted anomaly given solar output – the difference (observed – predicted) is called the residual which should have a mean of zero over the study period. The residuals should fluctuate from year to year, and they should behave in a random fashion.

Scatterplot of annual solar irradiance values (in Watts per square meter) and the annual global near-surface temperature anomalies (in °C) over the period 1910-2003 (from Balling and Sen Roy, 2005)

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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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Guest Commentary

Joel Schwartz
Visiting Fellow
American Enterprise Institute

What happens to future air pollution if the climate warms? Efthimios Tagaris and colleagues (Tagaris et al., 2007) have come closer than anyone before them in providing a realistic answer to this question. They predict that between 2001 and 2050, mean summer 8-hour ozone levels over the U.S. will decline by 11% to 28%, depending on the region, with an average decline of 20%. Fine particulate matter (PM2.5) will decline by 9% to 32%, with an average decline of 23%.

Tagaris et al.’s results stand in marked contrast to previous studies, nearly all of which predict higher air pollution levels over the U.S. in the future (e.g., Knowlton et al. (2004), Mickley et al. (2004), and Sitch et al. (2007)).

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In 1998, Balling et al. published an article in Climate Research dealing with summer and winter warming rates in several widely-used gridded temperature time series. As seen in Figure 1 below, the Balling crew (which includes several World Climate Report team members) found that winters were warming far more than summers, based on near-surface thermometer records, for a large part of northern and central Asia over the period 1946-1995. We repeated the analyses for the satellite-based lower-tropospheric temperature measurements over the period 1979-1995 and found the same red blob (wamer temperatures) over northern and central Asia. We suggested in the article that the build-up of greenhouse gases would most impact the coldest and driest air masses of the world, which just happen to be the air masses that cover northern and central Asia in the winter. Elevated greenhouse gas concentrations in warm and moist air masses would have less of an effect given the overwhelming greenhouse effect of naturally occurring water vapor. We had produced what appeared to be a smoking gun – the greenhouse “fingerprint” looked rather obvious in our analyses. Of course, finding that the coldest and driest air masses of the planet were warming slightly is seen by some as a blessing and not a great cause for concern – are residents of northern Siberia really worried about their winters being a bit warmer?

Figure 1. Seasonal difference (winter minus summer) in temperature trends (°C per decade) for the thermometer-based near-surface data over the period 1946-1995 (from Balling et al., 1998).

Well, the smoking gun has become a bit cloudier given a recent article in Nature entitled “Warming trends in Asia amplified by brown cloud solar absorption.”

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Guest Commentary

Joel Schwartz
Visiting Fellow
American Enterprise Institute

Growing plants absorb some of the carbon dioxide emitted by human burning of fossil fuels for energy. However, according to a new study in the journal Nature, ground-level ozone (AKA “smog”) will rise during the 21st Century and stunt plant growth. This will reduce CO2 uptake by vegetation, exacerbating CO2-induced greenhouse warming.

The study, which was performed by Stephen Sitch and colleagues from England’s Hadley Centre for Climate Change Research, is based on computer modeling of current and future ozone levels. To project future emissions of greenhouse gases and air pollutants, Sitch et al. relied upon the Intergovernmental Panel on Climate Change’s (IPCC) A2 scenario. The scenario includes projections of population, economic activity, energy use, and other factors that determined future emissions.

Unfortunately, comparison of Sitch et al.’s model results with actual trends in ozone and ozone-forming pollutants show that their study has nothing to do with reality.

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The global warming story is told over and over, and today every school child in America is aware that burning fossil fuels increases the atmospheric concentration of carbon dioxide, and they have learned that carbon dioxide is a greenhouse gas that will warm the Earth as its concentration increases. Of course, the United States is largely responsible for this mess, and children are given terrific suggestions on how they can get their parents to stop global warming.

Should someone begin to look more into the global warming issue, they will uncover literally hundreds of additional gems in the greenhouse apocalypse – they will rather quickly discover that Arctic region permafrost is melting at an unprecedented rate, and somehow this will lead us to a runaway greenhouse effect that might warm the Earth far more than any of us ever feared. The melting of permafrost is a solid, never-weakening pillar, of the greenhouse – global warming story.

But all is not as it seems (or as Al Gore would have you believe).

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