Controlling Black Carbon Soot Emissions Could Cut Rate of Climate Change by Half

If the world dramatically cuts levels of black carbon soot, methane and ozone forming HFCs – which can be done using existing technologies – we would cut the rate of global warming by 50% – increasing the chances of keeping temperature rise below 2 degrees C, or even 1.5C. We would slow the advance of climate change by decades.

Black carbon soot and other short-lived climate forcers, are potent climate pollutants that are causing up to half the warming in the Arctic region, and also much of the warming in the Himalayan-Tibetan Plateau, two super critical ecosystems that are warming two to three times faster than the global average.

Unlike CO2, which can remain in the atmosphere for centuries, these pollutants last only days to weeks in the atmosphere. Reducing short-lived climate forcers, including black carbon, tropospheric ozone, and methane would reduce local air pollution, save millions of lives and billions of dollars in crop losses annually. 

Black carbon consists of microscopic airborne particles of soot that come from diesel engines and industrial smokestacks in the developed world and residential cooking and heating stoves in the developing world.

This isn’t the first time that people have called for rapid action on the approximately 50% of global warming that is caused by pollutants other than carbon dioxide (CO2).  

To deal with this issue, The Global Alliance for Clean Cook Stoves was launched in 2010 during the 65th session of the UN General Assembly, as part of the Global Clinton Initiative and spearheaded by the UN Foundation.

New Research

In an innovative research project, researcher Professor V. Ramanathan and his daughter, Dr. Nithya Ramanathan, supplied local women in the Himalayan-Tibetan Plateau with cell phones to measure black carbon generated from their indoor cooking – a source of black carbon pollution that is a major killer of women and children.

The measurements showed that black carbon emissions are 3-5 times greater than currently represented in climate simulations.

"By changing the way they cook, the growing army of women enlisted by Ramanathan and his daughter can save the Himalayan Plateau," says Zaelke, while also saving their own lives and the lives of their children. "Of course they will need help from their governments and international partners."

By cutting their black carbon emissions from cooking, he says the women of Asia also can prevent the monsoon from shifting. Literally billions of people depend on the monsoons for the water for their crops and drinking. Zaelke says, "This may be even more important than saving the Himalayas."

Himalayan-Tibetan Plateau

"Black carbon’s damage to the Himalayan-Tibetan Plateau is bad news for the hundreds of millions of people – perhaps billions – who depend on the "Third Pole" for dry season irrigation needed for the crops that feed them," says Durwood Zaelke, President of the Institute for Governance and Sustainable Development.

The Tibetan Plateau – the planet’s largest store of ice after the Arctic and Antarctic – is warming at about three times the global average, with temperature increases of 0.3ºC or more per decade as measured over the past half-century.

Since the 1950’s, warming on the Tibetan side of the Himalayas has contributed to the retreat of over 80% of the glaciers, and over the past 10 years it’s lost 10% of its permafrost, permanently frozen ground. Permafrost holds vast stores of CO2 and methane trapped in the frozen ground which, if released, could trigger abrupt runaway warming.

Air pollution, monsoon floods and droughts are three of the most serious environmental threats to over 60% of the people living in Asia. In South Asia, a two-to-three-fold increase in soot loading from present day levels could substantially weaken the monsoon circulation, decrease rainfall by over 25% and significantly increase the frequency of drought.

The importance of black carbon soot was further confirmed this week in the UNEP/WMO report, "Integrated Assessment on Black Carbon and Tropospheric Ozone." According to its Summary for Policy Makers, full implementation of the 16 identified emission reduction measures of black carbon and ozone precursors could avoid 2.4 million premature deaths, mainly women and children, with more than 80% of the health benefits occurring in Asia.

Arctic Melt

It also contributes to the warming in the Arctic, where the white ice and snow acts as a defensive shield that reflects heat back to space.

The Arctic is currently warming at twice the rate of the global average, and melting there is expected to contribute to sea level rises of as much as 5 feet by the end of the century, according to a study by the International Arctic Monitoring and Assessment Program (AMAP), released in May. This is more than two and a half times higher than the sea level rise projected in 2007 by the Intergovernmental Panel on Climate Change.


Methane, another common air pollutant, interacts with sunlight and other volatile compounds to form ground-level ozone (smog). Reducing ground-level ozone can help increase crop yields and restore the ability of forests, grasslands and mangroves to sequester carbon.

In 2009, Zaelke, Ramanathan, Nobel Laureate Mario Molina and others, published a paper in the Proceedings of the National Academy of Sciences that outlined strategies to achieve near-term climate benefits by reducing short-term climate warming agents, including black carbon and tropospheric ozone.

The Molina paper also included measures to phase down another powerful climate forcer, hydrofluorocarbons, or HFCs, by using the Montreal Protocol treaty. "Global warming is a dauntingly complex issue," Zaelke says. "Fortunately, there are many actions that we can take today that can produce immediate cooling and save millions of lives. Knowing what’s at stake, we cannot afford to wait."

We’ve covered this issue in numerous articles over the past two years – it’s time to take serious action.

Cutting Black Carbon Soot Could Save Arctic

US Wants To Phase Out ‘Super’ Greenhouse Gases under Montreal Protocol

Overlooked Non-CO2 Strategies: 50% of Climate Warming

Fast-Action on Non-CO2 Agents Can Delay Climate Change

What is Soot’s Role in Climate Change?

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