|The Week That Was
September 9 , 2000
For many years now we have published about the much neglected greenhouse gas Methane. About half of what is emitted is the result of human activities. It also causes the water vapor content of the stratosphere to increase and attacks ozone in an important way. We were pleased therefore to find that the well-known global warming enthusiast James Hansen now feels that too much attention has been focused on CO2 and not enough on methane and other radiative components in the atmosphere.
Hansen, a National Aeronautics and Space Administration scientist, says the quickest way to slow global warming is to cut these other heat-trapping greenhouse gases first.
According to Hansen's new study in the Proceedings of the National Academy of Sciences: Global warming in recent decades has been driven mainly by non-CO2 greenhouse gases, such as chlorofluorocarbons (CFCs), methane (CH4) and nitrous oxide (N2O), rather than the products of fossil fuel burning, CO2 and aerosols.
Although burning fossil fuels has raised atmospheric levels of CO2, it also produces a haze of particles that reflects as much of the sun's energy back into space as the release of CO2 has trapped in the air, Hansen claims.
With CFC emissions declining, if sources of CH4 and ozone (O3) precursors were reduced in the future, their effect on the climate could be reduced to near zero over the next 50 years. Because many of these smog-forming gases also cause health problems or can harm agriculture, there are "strong economic reasons for wanting to eliminate them," says Hansen.
Meanwhile, emissions of carbon dioxide from human activities may be decreasing; Hansen said they shrank slightly in 1998 and 1999, even as the global economy grew. Thus, the world may find it easier and less costly to slow climate change by focusing on air pollution, concludes Hansen -- easier and less costly than scientists had previously thought.
Comment: It is the rate of increase of atmopheric CO2 that is decreasing. It is about 0.4% per year; yet climate models still assume a rate of 1% p.a.
Source: Andrew C. Revkin, "Study Proposes New Strategy to Stem Global
Warming," New York Times, August 19, 2000; James Hansen, et al.,
"Global warming in the twenty-first century: An alternative scenario,"
Proceedings of the National Academy of Sciences, August 29, 2000.
Journalist Gregg Easterbrook ["Get the Easy Greenhouse Gases First," NY Times, Aug. 29] is jubilant about Dr. James Hansen's study, which highlights the climate effects of non-CO2 greenhouse (GH) gases. We no longer need to worry so much about carbon dioxide from the burning of fossil fuels, Hansen's group concludes; we should concentrate more on other GH gases, like methane ("swamp gas" or CH4), at least in the short run.
Easterbrook opines that cutting the emission of methane should be a piece of cake; just keep natural gas pipelines from leaking and design landfills with greater care. These sources can be eliminated "with little sacrifice to our lifestyle or economic growth." So let's go ahead and adopt the Kyoto Protocol to control GH gases. After all, since we can reduce the total GH effect without pain, trading CH4 for CO2, why shouldn't the US Senate ratify the treaty, burnish the Clinton legacy, and give Al Gore a much-needed boost?
But Easterbrook's NY Times op-ed overlooks two important facts. Most of human-related methane around the world comes from the "exhaust" of cattle and from rice paddies. When first proposed 30 years ago, before measurements verified the existence of an increasing trend, it seemed like a strange idea; but it is now accepted by scientists. Doing away with these "natural" sources is not easy; it would mean also doing away with most of the world's population by starvation. People of Africa and Asia might not appreciate the suggestion, even if it preserves our lifestyle here.
The other objection comes from environmental zealots that are less concerned about a possible global warming and mainly want to stop growth. What better way to do this than to reduce the use of energy? Not just from fossil fuels, but also from nuclear and even "renewable" hydroelectric. If you don't believe this, just watch what's happening in certain affluent European nations where "Green" political parties have gained a crucial voice.
Jim Hansen is a careful scientist who well understands the uncertainties of climate science. He is also honest enough not to hide them or sweep them under the rug. I hope he also has a thick skin. He will need it, particularly if others distort his results for political purposes. He will be fair game for the anti--growth lobby who see their goals at risk.
His position is also likely to upset the negotiators from 180 nations who will meet in The Hague just one week after the US November elections. There they will try to put the finishing touches on the Kyoto Protocol, aiming primarily to reduce CO2 emissions. Hansen's bombshell adds another wild card to the debate about climate change and what, if anything, should be done about it.
The Environmental Protection Agency wants to declare the nation's highest-use herbicide, atrazine, a likely carcinogen. But in a largely unreported development, the agency's own 15-member Scientific Advisory Panel unanimously rejected an EPA attempt to elevate atrazine to that category.
The panel found that while massive doses of atrazine caused mammary tumors in a single type of rat, similar dosing of another type of rat and three types of mice caused no problems. The panel said the mechanism that causes tumors in that one type of rat is well understood and does not apply to humans.
The chemical is a primary weed killer for more than 30 crops and banning it would do untold damage to U.S. agriculture. It is used on about two-thirds of U.S. corn and sorghum, and as much as 90 percent of U.S. sugar cane. Numerous studies have shown that for corn growers, using alternatives to atrazine would entail a loss of around $35 an acre due to higher costs of treatment and lower yields. Atrazine is also used in about 80 other countries.
Source: Michael Fumento (Hudson Institute), "The EPA Chokes: Atrazine Scare Fails in Face of Real Science," Investor's Business Daily, July 12, 2000.
The controversy surrounding New York City's reaction to the threat posed by the West Nile virus has spurred commentary over real versus perceived risks in our society. Writing for The Washington Post, David Ropek, director of risk communication for the Harvard Center for Risk Analysis, argues that irrational fears are often promoted into poor public policy.
"In a world of finite resources, we can only protect ourselves from so many things. If we overspend on risks which are real but of relatively low magnitude, we have less to spend on greater threats."
Ropek's article, as well as one by Kirk Johnson (The New York Times) and another by Sally Squires in The Washington Post look at the perception factors which cause people to create strict guidelines and spend millions for protection from something with a relatively low risk over which there is less control (such as pesticides, asbestos, radon, or contracting a mosquito-borne virus in New York City); versus what we do to prevent smoking, cardiovascular disease or automobile accidents, which are much greater threats to public health and have a great degree of individual control