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Satellites Tell Us if Global Warming Real

A group of scientists in the U.S. and England says there is no proof we are experiencing global warming, and if we are, increased greenhouse gas emissions may not be the cause. They argue that temperature rise projections this century are ?unknown and unknowable? and say it?s ?a media myth? that only a few scientists share their skepticism.

The scientists, a group convened by the American George C. Marshall Institute, have published a report which claims to be ?the result of an extensive review by a distinguished group of scientists and public policy experts of the science behind recent findings of the United Nations Intergovernmental Panel on Climate Change (IPCC).?

The U.S. group includes former CIA director and defense secretary James Schlesinger, and Richard Lindzen, professor of meteorology at M.I.T. The report says the IPCC?s conclusions ?have become politicized and fail to convey the underlying uncertainties that are important in policy considerations.?

The report criticizes projections of climate change based on models and assumptions which ?are not only unknown, but unknowable within ranges relevant for policy-making,? models which ?do not adequately characterize clouds, water vapor, aerosols, ocean currents and solar effects? and accuses the IPCC of a failure ?to reproduce the difference in trends between the lower troposphere and surface temperatures over the past 20 years.?

The authors say, ?The IPCC simulation of surface temperature appears to be little more than a fortuitous bit of curve-fitting rather than any genuine demonstration of human influence on global climate.?

Philip Stott, of the University of London, says, ?The authors challenge the key contradiction at the heart of the Kyoto Protocol, the global climate agreement -- that climate is one of the most complex systems known, yet that we can manage it by trying to control a small set of factors, namely greenhouse gas emissions. Scientifically, this is not mere uncertainty: it is a lie?You can no more predict successfully the outcome of doing something as of not doing something. Kyoto will not halt climate change.?

Eileen Claussen, of the Pew Center on Global Climate Change, used to work at the State Department and helped shape U.S. climate policy. She says, ?This report dismisses the findings of the IPCC as alarmist, yet they are widely accepted as representative of the current state of scientific knowledge. A panel of the U.S.?s own National Academy of Sciences (which included Richard Lindzen) expressed general agreement with the IPCC?s finding that warming is occurring, and that it is at least partly caused by humans.

?Uncertainty cuts both ways. Some of the IPCC?s scenarios have been criticized as unduly pessimistic, others as unduly optimistic. What is important is that they reflect a balance of reasonable futures, and that the scientific findings should be based on the peer-reviewed literature. The IPCC has been able to accomplish exactly that.

?And Kyoto was only intended to be a first step in a long journey.?

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The Philadelphia Inquirer reports that something remarkable has happened since 1991: The growing season has grown. The period in which the official temperature has dipped to freezing has become noticeably shorter.

In the 30 years from 1961 to 1990, the first freeze showed up at Philadelphia International Airport, on average, on October 31. The last freeze has usually been on April 8. However, since 1991, the average first freeze hasn?t occurred until nine days later, on November 9, with the last one on March 27. Overall, that?s a 21-day difference. Compared with the 1960s, it?s a 27-day difference.

Between 1961 and 1990, an April freeze occurred every year except for two. In the 11 years since then, six Aprils have been freeze-free.

This pattern shows that a remarkably warm period took hold around 1990 and has continued this winter. Evidence of this warming trend has shown up in plant life throughout Pennsylvania and in much of the Northern Hemisphere, according to Compton Tucker of NASAs Goddard Space Flight Center. Tucker and a group of researchers have published a paper documenting a significant increase in plant growth since 1982 in the temperate region that includes Philadelphia, Madrid and Beijing.

Using two decades of satellite data, they found a 12 percent increase in vegetation density. The changes were particularly pronounced in parts of Russia. While the increases weren?t as dramatic in North America, they were significant in the grasslands of the Upper Midwest and the forests of the East. Pennsylvania showed an increase in plant density of about 13 percent over the 20-year period.

This was reduced in 1991 and 1992 after the eruption of Mount Pinatubo in the Philippines. The tremendous veil of volcanic ash spewed by Pinatubo had a worldwide cooling effect. The fact that the vegetation index went up again once the volcanic dust left the atmosphere strongly suggests that the plants were thriving on warmth.

However, two decades of data isn?t much in the lifetime of Earth. Also, other satellite data have shown some warming but not nearly the level of warming measured by surface thermometers throughout the world. And temperature is hardly the only thing that drives plant growth, says Olga Wickenhauser, a horticulture specialist at Rutgers University. Rain is important, and light is even more important. No matter how warm it has been since 1990, Wickenhauser says, it?s too short a period to prove that there are significant changes in vegetation patterns.

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The European space company Arianespace is preparing to launch the return flight of its Ariane 5 rocket, which is important to maintaining Europe?s independent access to space. It will launch Envisat, which weighs eight tons and is the largest earth observation satellite ever built in Europe.

The Envisat is the most important satellite ever launched to monitor changes in the earth?s environment. It carries equipment to perform 10 simultaneous monitoring operations that will provide information on phenomena such as global warming, ozone-layer depletion, changing vegetation patterns and natural hazards such as earthquakes and floods.

The main scientific importance of the project lies in its ability to examine the inter-relationships between these phenomena, which previous satellites have been unable to do. The aim is to provide more conclusive information to avoid scientific uncertainties over the relationship between global warming and greenhouse gas emissions.

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