Cuts in Methane, Soot Emissions Quickly Save Lives, Climate, Crops

NEW YORK, New York, January 13, 2012 (ENS) – Reducing emissions of black carbon and methane into the atmosphere could slow climate change, increase crop yields and prevent hundreds of thousands of premature deaths each year, finds new NASA-led research published today.

Carbon dioxide is the primary driver of climate change over the long term, because it remains in the atmosphere 200 to 300 years. The scientists say reducing black carbon and methane emissions would have a more immediate impact because these two pollutants circulate out of the atmosphere more quickly than CO2. Methane has an atmospheric lifetime of about 12 years, while black carbon falls to the ground within a few days.

While all regions of the world would benefit, countries in Asia and the Middle East would see the biggest health and agricultural gains from emissions reductions, says lead researcher Drew Shindell of NASA’s Goddard Institute for Space Studies in New York City.

NASA scientist Dr. Drew Shindell (Photo courtesy American Physical Society)

“We’ve shown that implementing specific practical emissions reductions chosen to maximize climate benefits would also have important win-win benefits for human health and agriculture,” said Shindell. The research was published today in the journal “Science.”

The new study builds on a United Nations Environment Program-World Meteorological Organization report published in February 2011, also led by Dr. Shindell, which indicated that reducing emissions of black carbon and methane could slow the rate of climate change over the next 50 years.

UNEP Executive Director Achim Steiner said of the newest findings, “The scientific case for fast action on these so-called ‘short-lived climate forcers’ has been steadily built over more than a decade, and this study provides further focused and compelling analysis of the likely benefits at the national and regional level.”

Black carbon and methane have many sources. Reducing emissions would require that societies make multiple infrastructure upgrades, the researchers said.

To determine which changes would be most effective, Shindell and an international team of scientists considered 400 measures to control these pollutants based on technologies evaluated by the International Institute for Applied Systems Analysis in Laxenburg, Austria. They modeled the impact of the various emissions reductions with computer models developed at GISS and the Max Planck Institute for Meteorology in Hamburg, Germany.

The scientists zeroed in on 14 measures with the greatest climate benefit. All 14 would curb the release of either black carbon or methane, pollutants that contribute to climate change and damage human or plant health either directly or by leading to the formation of ozone, a key component of smog and itself a greenhouse gas.

Diesel smoke (Photo credit unknown)

The models showed the greatest widespread benefits from the methane reduction because it is evenly distributed throughout the atmosphere.

Black carbon falls out of the atmosphere after a few days, so the benefits are stronger in regions covered in snow and ice.

The small sooty particles absorb radiation from the Sun, causing the atmosphere to warm and rainfall patterns to shift. Falling from the atmosphere, they blanket ice and snow, reducing their reflectivity and hastening global warming.

Black carbon, emitted by burning fossil fuels and biomass such as wood or dung, can worsen respiratory and cardiovascular diseases.

To minimize black carbon emissions, the scientists found the greatest impact from strategies such as installing filters in diesel vehicles, keeping high-emitting vehicles off the road, upgrading cooking stoves and boilers to cleaner burning types, installing more efficient kilns for brick production, upgrading coke ovens and banning agricultural burning.

Some of these strategies are already in effect in the United States. In California, new regulations for reducing emissions from heavy diesel trucks and buses took effect on January 1. By requiring that trucks and buses to install diesel particulate matter filters, the regulation reduces emissions from the nearly one million heavy-duty diesel vehicles that operate in the state.

Exposure to smoke from traditional cookstoves and open fires deadly, especially for women and young children. (Photo by Project Gaia courtesy Global Cookstove Alliance)

Nationally, the U.S. Environmental Protection Agency is raising the Clean Air Act standards for boilers and incinerators.

Internationally, exposure to smoke from traditional cookstoves and open fires used by nearly three billion people in the developing world, causes two million premature deaths annually, with women and young children the most affected. The Global Alliance for Clean Cookstoves, a public-private partnership led by the United Nations Foundation, aims to help 100 million households to adopt clean and efficient cookstoves and fuels by 2020.

Methane, a colorless, flammable substance that is a major constituent of natural gas, is both a potent greenhouse gas and a precursor to ground-level ozone.

For methane, the key strategies that produced the greatest reductions were capturing gas escaping from coal mines and oil and natural gas facilities, as well as reducing leakage from long-distance pipelines, preventing emissions from city landfills, updating wastewater treatment plants, aerating rice paddies more, and limiting emissions from manure on farms.

Internationally, many countries are already acting to reduce methane emission. The Methane to Markets Partnership, which began in 2004 with 13 countries is now the Global Methane Initiative with 40 countries plus the European Commission, accounting for some 60 percent of global methane emissions.

Methane gas can be captured underground and used to generate electricity. These pipes are part of a methane capture system at a landfill in the state of Washington. (Photo courtesy King County Solid Waste Division)

Under this initiative, backed by the the Asian Development Bank and the Inter-American Development Bank, public and private sector organizations are working with government agencies to implement methane reduction projects in agriculture, coal mines, landfills and oil and gas systems.

Shindell and his team concluded that the 14 best control measures could slow mean global warming 0.9°F (0.5°C) by 2050, increase global crop yields by up to 135 million metric tons per season and and prevent hundreds of thousands of premature deaths a year.

The measures would provide the greatest protection against global warming to Russia, Tajikistan and Kyrgyzstan, countries with large areas of snow or ice cover.

Iran, Pakistan and Jordan would experience the most improvement in agricultural production.

Southern Asia and the Sahel region of Africa would see the most beneficial changes to precipitation patterns.

India, Bangladesh and Nepal would see the biggest reductions in premature deaths. The study estimates that globally between 700,000 and 4.7 million premature deaths could be prevented each year.

“Protecting public health and food supplies may take precedence over avoiding climate change in most countries, but knowing that these measures also mitigate climate change may help motivate policies to put them into practice,” Shindell said.

Copyright Environment News Service (ENS) 2012. All rights reserved.