This article is from the In-Depth Report 400 PPM: What's Next for a Warming Planet

How to Buy Time in the Fight against Climate Change: Mobilize to Stop Soot and Methane

A short list of relatively simple actions taken to reduce greenhouse gases other than CO2 could help put the brakes on global warming--if implemented globally

Courtesy of U.S. Office of Mine Safety and Health Research

Humanity has done little to address climate change. Global emissions of carbon dioxide reached (another) all-time peak in 2010. The most recent international talks to craft a global treaty to address the problem pushed off major action until 2020. Fortunately, there's an alternative—curbing the other greenhouse gases.

Specifically, in the case of rapid action to slow catastrophic climate change, the best alternatives appear to be: methane and black carbon (otherwise known as soot). A new economic and scientific analysis published in Science on January 13 of the benefits of cutting these two greenhouse gases finds the benefits to be manifold—from human health to increased agricultural yields.

Even better, by analyzing some 400 potential soot- and methane-emission control measures, the international team of researchers found that just 14 deliver "nearly 90 percent" of the potential benefits. Bonus: the 14 steps also restrain global warming by roughly 0.5 degree Celsius by 2050, according to computer modeling.

That's because both methane and black carbon only remain in the atmosphere for a short time compared with CO2. As atmospheric physicist Veerabhadran Ramanathan of the Scripps Institution of Oceanography at the University of California, San Diego, said of such efforts to reduce atmospheric soot a few years ago: "If the world pays attention and puts resources to it, we will see an effect immediately. I'm talking weeks, at most a few months, not decades or centuries."

The 14 measures that would immediately slow global warming are:

—Eliminate methane releases from coal mines—particularly in China—by capturing it and burning it.
—Eliminate the venting or accidental release of methane co-produced by oil drilling (and, of course, gas drilling itself), particularly in Africa, the Middle East and Russia.
—Capture gas from landfills in the U.S. and China as well as promote recycling and composting of biodegradable trash.
—Occasionally aerate flooded rice paddies to prevent the growth of methane-producing microbes.
—Stop leaks from natural gas pipelines, particularly in Russia.
—Use bio-digesters—vessels in which microbes break down manure into gas—to cut methane from livestock globally.
—Update wastewater treatment plants to capture methane.
—Filter the soot produced by incomplete combustion of diesel fuel in vehicles, and attempt to eliminate inefficient internal combustion engine vehicles entirely.
—Replace indoor cooking and heating fires with clean-burning cookstoves fired either by wood, manure or other biomass or, even better, methane.
—Replace traditional brick kilns with more advanced firing methods.
—Replace traditional ovens for turning coal to coke with modern technologies.
—Ban the open burning of crop stubble and other agricultural waste.

The researchers estimate that cutting those 14 together could avoid between 700,000 and 4.7 million premature deaths (largely from smoky, unhealthy air) and increase crop yields by between 30 million and 135 million metric tons (due to concomitant reductions in ground-level ozone, otherwise known as smog, which forms from fugitive methane and blights crops in Brazil, China, India, the U.S. and elsewhere). In addition, the economic analysis suggests that many of these measures provide more value in benefits than they cost to implement.

Finally, the really good news is that every single one of the required technologies already exist and are being used in various parts of the world. For example, Senegal has "switched virtually its entire population from traditional stoves to modern ones, so it can be done," climate scientist Drew Shindell of NASA's Goddard Institute for Space Studies, lead author of the study, wrote in an e-mail. It is simply a matter of global adoption or, as the United Nations Environment Programme put it in a similar analysis last year, "much wider and more rapid implementation is required to achieve the full benefits."

In addition to saving lives, stopping soot may also preserve endangered ecosystems, such as the mountain glaciers of the Himalayas and Karakoram or Arctic sea ice. In fact, the computer modeling suggests cutting black carbon could forestall as much as two thirds of the warming in the Arctic—the fastest warming region of the globe—over the next 30 years. Even more significantly (from the human perspective), eliminating the atmospheric smut known as the "Asian brown cloud" could help maintain the monsoon patterns that bring water to India while reducing drought risk in places like the Sahel.

This doesn't mean that humanity would not have to deal with CO2 emissions—and would not be storing up future trouble by continuing to emit at our present pace—but it would buy time and, perhaps even more importantly, significantly reduce the chances of catastrophic climate change. Adding in cuts in yet more non-CO2 greenhouse gases—like the hydrofluorocarbons currently being phased out under the terms of the Montreal Protocol to eliminate the ozone hole—will also help. "These are things to do in addition to but not instead of reducing CO2 emissions," Shindell emphasized.

So why isn't this happening already? First and foremost, it is—in some parts of the world, at least. But short-term cost considerations, institutional structures and even societal priorities can stand in the way. For example, limited budgets might keep a municipality from installing methane capture at the local landfill in the U.S. Or an oil company might refrain from investing in similar methane capture at its wells because it can make more money investing in opening a new field instead. "In poor places, it really can be a lack of the upfront costs," Shindell added. There's also the not insignificant challenge of implementing such solutions globally—otherwise known as the problem of scale—as well as overcoming the reasons of engaging in traditional practices, such as burning the residue in agricultural fields to increase fertility, in the first place.

But there's a more fundamental reason for the inertia, according to the researchers, who note that "the benefits would not necessarily accrue to those incurring costs." That also explains our inaction on climate change generally. Or as Shindell noted "It's not trivial to get this done—even if it's beneficial for society as a whole."

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