Less Soot, Less Methane Equals Slower Global Warming, Study Finds
By Charlene Porter
Staff Writer
Washington - Taking steps to reduce just two air pollutants - soot and methane - could go a long way toward slowing global warming, according to the findings of a NASA-led study published January 12.
Reduction measures would have the added benefit of improving health and boosting agricultural production, according to a summary issued by NASA.
Implementing 14 key air pollution control measures could slow global warming by an estimated 0.5 degrees Celsius (0.9 degrees Fahrenheit) by 2050. Severe environmental disruption might be averted if global temperature increases from the pre-industrial level are kept below 2 degrees Celsius, though there is no broad agreement on a "safe level" of warming.
Led by Drew Shindell of NASA's Goddard Institute for Space Studies, the research finds that emission reductions could increase global crop yields by up to 135 million metric tons per season. Further, hundreds of thousands of premature deaths due to respiratory problems would be prevented with implementation of pollution-reduction methods evaluated by an Austrian research group.
"We've shown that implementing specific practical emissions reductions chosen to maximize climate benefits also would have important 'win-win' benefits for human health and agriculture," Shindell said.
Black carbon (soot) emissions result from burning fossil fuels or biomass, and they can worsen a variety of respiratory and cardiovascular diseases. They aggravate global warming by absorbing radiation from the sun. Widely emitted from smokestacks and chimneys, they eventually settle back down to earth, darkening ice and snow, reducing reflectivity and pushing temperatures higher.
Colorless and flammable methane is a greenhouse gas and a precursor to ground-level ozone, another health irritant.
Levels of carbon dioxide emissions have dominated the international debate about climate change, and over the long term, it is the greenhouse gas that most influences warming. But in the short term, measures to control soot and methane can have a significant impact, according to the research.
Reducing emissions of these two greenhouse gases is no small commitment, however, and would call for multiple infrastructure upgrades. The International Institute for Applied Systems Analysis in Laxenburg, Austria, has evaluated about 400 possible control measures, from which Shindell and his team chose those studied.
Effective ways to reduce methane emissions include:
.. Capturing gas escaping from coal mines and oil and natural gas facilities.
.. Reducing leakage from long-distance pipelines.
.. Preventing emissions from decaying matter in city landfills.
.. Updating wastewater treatment plants.
.. Limiting emissions from manure on farms.
For reductions in black carbon emissions, the NASA research recommends:
.. Installing filters in diesel vehicles.
.. Keeping high-emitting vehicles off the road.
.. Upgrading cooking stoves and boilers to cleaner-burning fuels.
.. Installing more efficient kilns for brick production.
The Goddard Institute worked with the Max Planck Institute for Meteorology in Hamburg, Germany, to develop computer models capable of evaluating how widespread adoption of these actions could reduce emissions.
Shindell acknowledges that implementation of all these practices on a wide scale could be difficult.
"Protecting public health and food supplies may take precedence over avoiding climate change in most countries," Shindell said, "but knowing that these measures also mitigate climate change may help motivate policies to put them into practice."
The potential of these emission-reducing strategies has been cited in earlier research, notably a report jointly released by the U.N. Environment Programme (UNEP) and the World Meteorological Organization in 2010.
"The scientific case for fast action on these so-called short-lived climate forcers has been steadily built over more than a decade," said UNEP Executive Director Achim Steiner. "This study provides further focused and compelling analysis of the likely benefits at the national and regional level."
The study demonstrates "a clear and urgent need to reduce emissions of near-term climate pollutants," said Todd Stern, the U.S. State Department's special envoy for climate change. "The United States has been concerned with these pollutants for some time, and is actively pursuing efforts through the Global Methane Initiative and the Global Alliance for Clean Cookstoves to combat their effects on air quality and warming the climate."
The Global Methane Initiative improves methane recovery and use as a clean energy source. According to the U.S. Environmental Protection Agency, the initiative is engaged in nearly 600 projects around the world that have reduced cumulative methane emissions by 128.3 million tons of carbon dioxide-equivalent since 2005.
The United States joined a variety of partners to launch the Global Alliance for Clean Cookstoves in 2011, a project that will save lives and reduce air pollution by broadening the availability of cookstoves using cleaner fuels. Smoke and pollutants from the use of fuels such as wood and dung are a threat to respiratory health in developing-world homes.
The latest estimate of the amount of greenhouse gases in the atmosphere reached a new high, and the rate of increase has accelerated, according to the World Meteorological Organization's Greenhouse Gas Bulletin. Between 1990 and 2010, according to the report, there was a 29 percent increase in the warming effect on the planet's climate system from greenhouse gases.
(This is a product of the Bureau of International Information Programs, U.S. Department of State.)
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