NASA urges practical solutions for reducing greenhouse gases

Next to landfills, enteric fermentation in domestic livestock is the highest producer of atmospheric methane, a major contributor to global warming

By Environmental News Network staff

Greenhouse gases are the driving force behind global warming. But practical solutions abound to reduce these emissions and slow Earth's warming trend, according to a report from scientists at NASA's Goddard Institute for Space Studies.

A global effort, they suggest, to reduce air pollution, especially tropospheric ozone and black carbon (soot), would not only slow global warming but also help unite the interests of developed and developing countries.

"I think this is a more optimistic assessment of the chances for keeping climate change moderate in the next 50 years, and the way to do that is to focus on stopping the growth of several gases," said James Hansen, co-author of the report "Global Warming in the 21st Century: An Alternative Scenario."

"If you add up the sum of other gases methane, tropospheric ozone, chlorofluorocarbons and nitrous oxide they cause a slightly larger forcing (imposed changes in the Earth's energy balance with space) than you get from carbon dioxide," explained Hansen, head researcher at GISS. "It makes a lot of sense to try to reduce these gases because, in some ways, it's easier and some have undesirable effects. Tropospheric air pollution is harmful to human health and agricultural productivity."

Hansen isn't ready to let carbon dioxide off the hook, however. Research into technology that reduces carbon dioxide emissions, such as carbon sequestration, and alternative energy such as fuel cells, must continue, he said.

"Energy use will continue to increase, so we have to keep the carbon dioxide growth rate from accelerating. We need to have a continuous trend toward the de-carbonization of the energy supply the trend to replace coal with gas as well as renewables and clean energy sources," said Hansen.

According to Hansen, greenhouse gases created by humans and added to the air since the Industrial Revolution cause warming equal to that of two 1-watt light bulbs over every square yard of Earth's surface

The good news is that growth rate of carbon dioxide increased only slightly in the past 20 years, even though much of the developing world had rapid economic growth.

This suggests that opportunities exist to achieve reduced emissions without sacrificing economic growth, according to Hansen.

For example, he said, if the World Bank encouraged investments in modern technology and air quality control in India and China, two of the world's most polluted countries, reductions in tropospheric ozone and black carbon would not only improve local health and agricultural productivity but also benefit global climate and air quality, Hansen said.

Some solutions to reducing greenhouse gases other than carbon dioxide are are already in place, he added.

Methane, one of the largest causes of climate change, can easily be captured and reused as fuel. Methane produced by rice cultivation, possibly the largest anthropogenic source, can be reduced by factors such as fertilizer choice and intermittent irrigation. Farmers can also adjust the diet of livestock to reduce methane emissions.

Tropospheric ozone is a stew of volatile organic compounds and nitrogen oxides emitted by transportation vehicles, power plants and industrial processes. Because ozone in the free troposphere can have a lifetime of weeks, it is a global problem illustrated by the fact that emissions from Asia have a significant effect on air quality in the United States. Developing technology is the best cure for these emissions.

"In California, they are beginning to require much cleaner fuels for transportation vehicles," said Hansen. "That kind of thing could go a long way in reducing pollutants."

"There needs to be a more concerted global effort to reduce air pollution," he added.

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"Global Warming in the 21st Century: An Alternative Scenario."
Goddard Institute for Space Studies
E.P.A.'s site on global warming
   •methane
   •nitrous oxide
   •carbon dioxide
The Montreal Protocol
EPA's Office of Air and Radiation

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