Re: Global warming: It's happening
by Kevin E. Trenberth
A letter from Jon Traudt
Date: Wed, 17 Nov 1999 14:32:01 -0600
Organization: Health & Energy Company
From: Jon Traudt" firstname.lastname@example.org
Subject: Response to "Global warming: It's happening"
Are We Triggering Abrupt and Extreme Climate Change?
I am writing in response to the excellent naturalSCIENCE article Global warming: It's happening by Kevin E. Trenberth. The consensus on the accumulated global warming due to mankind's actions appears to be only about 1 degree F. So far, that is. However, as the following information suggests, we may soon experience more rapid global warming.
In the October 1998 issue, The Economist concluded, "Climate change is a legitimate worry. Although still riddled with uncertainties, the science of climate change is becoming firmer: put too much carbon in the atmosphere and you might end up cooking the earth, with possibly catastrophic results." Could we possibly be in the process of triggering abrupt and extreme climate change that mankind cannot reverse and may not survive?
Mankind may have already initiated a chain reaction that will accelerate global warming. The United States emits more than 1,800 million metric tons of carbon equivalent each year, more than 6 tons per person (See "Emissions of Greenhouse Gases in the United States, 1998" from the U.S. Energy Information Administration). The accumulation of greenhouse gases in the atmosphere as a result of such extravagant energy use, may, by warming the Earth, already have initiated conditions that will accelerate the future build-up of greenhouse gases. Four mechanisms, whereby the warming that has already occurred can be expected to give rise to further warming are as follows.
- As Arctic regions warm, huge areas of permafrost thaw, allowing thick layers of long-frozen plant material to decay and release both methane and carbon dioxide (See The Greenhouse Effect, Greenhouse Gases, and Global Warming, a report published by the Goddard Institute for Space Studies). That warming has been about four times greater in polar regions than near the equator, greatly accentuates this effect.
- The solubility of carbon dioxide in water decreases as temperature rises. Thus, as oceans warm, their ability to absorb carbon dioxide from the atmosphere decreases. Further,
methane, a more potent greenhouse gas than carbon dioxide, is released from gas hydrate deposits on the sea floor when the local water temperature rises a few degrees above freezing. (See page 76 of the November 1999 issue of Scientific American).
- Global warming has resulted in drought in many regions. Droughts reduce the accumulation of plant biomass, which sequesters a large portion of the earth's store of labile carbon. The loss of vegetation caused by drought thus results is a net release of carbon from the biosphere to the atmosphere.
- The Surface Heat Budget of the Arctic Ocean Project, or SHEBA, an international expedition to the Arctic, has documented changes in the ice pack consistent with changes expected as a result of global warming. The ship, CCGS Des Groseilliers, is located in the black area in the middle of the satellite image, which shows much of the ice is covered by dark melt ponds.
Preliminary findings from SHEBA show that the Arctic ice sheet is about five percent smaller, and one meter thinner, than in the 1970s. Scientists believe that the on-going disappearance of the ice pack could accelerate global warming because ice reflects more incoming solar radiation than does the ocean. Part of the melting is due to dark dust from human activities that settles on the ice and increases absorption of heat from the sun.
Energy efficient methods and products are available now that can make a big difference in stopping this threat. Greater use of renewable energy systems and energy efficiency could curb global warming, ensuring better health for Americans as well as new job markets and another competitive edge for the US economy.
Global warming is happening already, and it is reducing our quality of life. Is mankind wise enough to act soon enough to avoid triggering a potentially disastrous global warming?
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