*EPF511 11/19/2004
Text: Trace Gases Key to Halting Global Warming, NASA Scientists Say
(Reducing methane, other non-CO2 gases might save global coastlines) (1140)

NASA researchers suggest that reducing trace gases in the atmosphere might let the climate stabilize so global warming would be less than 1 degree Celsius (C), a level needed to maintain global coastlines.

According to a November 18 Columbia University press release, carbon dioxide (CO2) emissions must also be slowed to prevent global warming, but CO2 reduction is more feasible if methane and other trace gases decrease.

Humans have increased the amount of CO2 in the air from 280 to 380 parts per million units of air (ppm) since 1900. If the world continues to increase emissions of CO2, methane and ozone, the likely result will be a large climate change with a sea level rise of a few meters.

James Hansen and Makiko Sato of NASA's Goddard Institute for Space Studies at the Columbia University Earth Institute suggest that avoiding a large climate change requires the global community to consider aggressive reductions in emissions of CO2 and non-CO2 gases called trace gases.

Hansen and Sato said that if methane and other trace gases are reduced, climate could be stabilized, with warming less than 1 degree C, at CO2 levels of 520 ppm, the level needed to maintain global coastlines.

If trace gases continue to increase at the current levels, CO2 would have to be kept under 440 ppm, a practically impossible goal. New technologies by mid-century might help keep CO2 levels from exceeding 520 ppm, they said.

The co-authors suggest that non-CO2 gases could be addressed via a Montreal Protocol-like process, or by adding gases to the requirements of the Montreal Protocol, an international agreement originally signed in 1987 and designed to protect the stratospheric ozone layer.

Information about the Goddard Institute for Space Studies is available at http://www.giss.nasa.gov.

Text of the Columbia University press release follows:

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Columbia University Earth Institute
Press release, November 18, 2004

Trace gases are key to halting global warming

The Earth Institute at Columbia University, NYC -- Researchers suggest that reductions of trace gases may allow stabilization of climate so that additional global warming would be less than 1° C, a level needed to maintain global coastlines. Although carbon dioxide emissions, an inherent product of fossil fuel use, must also be slowed, the required carbon dioxide reduction is much more feasible if trace gases decrease.

In the current edition of Proceedings of the National Academy of Sciences, Drs. James Hansen and Makiko Sato of NASA's Goddard Institute for Space Studies (GISS) at the Earth Institute at Columbia University suggest that avoidance of large climate change requires the global community to consider aggressive reductions in the emissions of both carbon dioxide and non-carbon dioxide gases called trace gases. Humans have already increased the amount of carbon dioxide in the air from 280 parts per million (ppm) to 380 ppm. If the world continues on its current trajectory of increasing carbon dioxide, methane and ozone, the likely result will be large climate change, with sea level rise of a few meters or more.

Hansen and Sato point out that if methane and other trace gases are reduced, climate could be stabilized, with warming less than 1°C, at carbon dioxide levels of 520 ppm. However, if the trace gases continue to increase, carbon dioxide would have to be kept beneath 440 ppm. A cap of 440 ppm seems practically impossible to stay under due to existing energy infrastructure. However, Hansen and Sato suggest that, with the possibility of new technologies by mid-century, it is feasible to keep carbon dioxide levels from exceeding approximately 520 ppm.

The co-authors suggest that the non-CO2 gases could be addressed via a Montreal Protocol-like process, or by adding additional gases to the Montreal Protocol itself. The Montreal Protocol has been very effective in reducing emissions of gases that destroy stratospheric ozone. Developed and developing countries have worked together harmoniously in this process, with the World Bank providing support for participation of developing countries.

"Carbon dioxide is the main greenhouse gas (GHG), and slowdown of its emissions must have priority. It will be a growing issue in international relations for decades, if not longer," says Dr. Hansen. "However, that does not necessarily mean that 'Kyoto' is the best way to address the trace gases. 'Kyoto' gives too little or no weight to gases such as methane, the trace gas HFC-134a, ozone and the precursor gases that form ozone. We could get moving now on non-carbon dioxide gases with benefits such as improved human health, in addition to a slowing of global warming. The resulting international good will might also make discussions about carbon dioxide more productive."

"The slowdown in the growth rate of the GHGs contribution to global warming from the peak in the 1980s is due mainly to the phase out of CFCs as dictated by the Montreal Protocol. This success could be diminished by increases of other trace gases not controlled by the Montreal Protocol. We argue that it is well worth extending the Montreal Protocol machinery to phase out many of these trace gases," added Sato.

Additionally, the co-authors warn that trace gases also influence the rate at which major atmospheric GHGs are sequestered, a primary strategy for curbing global warming from carbon dioxide emissions. As global warming proceeds, the Earth naturally releases carbon dioxide, methane and nitrous oxide. Therefore, another benefit of reducing trace gases and their warming effect is a reduction of the induced 'natural' releases of these gases. Other bonuses of reducing warming agents such as ozone and soot are improvements in human health and agricultural productivity.

NASA provided funding for this study, and the NOAA Climate Monitoring and Diagnostics Laboratory provided access to current measurements of GHGs.

The Goddard Institute for Space Studies, part of the Earth Institute at Columbia University, is the only urban laboratory of the National Aeronautic and Space Administration (NASA). The Goddard Institute is a climate research center that models and monitors earth systems. In addition to research, it plays an important teaching function, running educational programs at more than twenty universities, schools and organizations in the New York metropolitan area. For more information, visit http://www.giss.nasa.gov.

The Earth Institute at Columbia University is the world's leading academic center for the integrated study of Earth, its environment and society. The Earth Institute builds upon excellence in the core disciplines-earth sciences, biological sciences, engineering sciences, social sciences and health sciences-and stresses cross-disciplinary approaches to complex problems. Through research, training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world's poor.

For more information, visit www.earth.columbia.edu.

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(Distributed by the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)

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