Complementary Action to Curb 'Soot' & 'Smog' Pollution Could Help Limit Global Temperature Rise

Fast action on pollutants such as black carbon, ground level ozone and methane may help limit near term global temperature rise and significantly increase the chances of keeping temperature rise below 2degC--and perhaps even 1.5degC--a new assessment says.

Protecting the near-term climate is central to significantly cutting the risk of "amplified global climate change" linked with rapid and extensive loss of Arctic ice on both the land and at sea.

Fast action might also reduce losses of mountain glaciers linked in part with black carbon deposits while reducing projected warming in the Arctic over the coming decades by two thirds. Black carbon--basically, soot--is produced by incomplete combustion of carbon fuels, particularly diesel, wood, and coal.

The scientists behind the assessment, coordinated by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) whose Secretariat is provided by the Stockholm Environment Institute (SEI), also point to numerous public health and food security opportunities above and beyond those linked with tackling climate change.

Earthjustice attorney Erika Rosenthal, a lead author on the policy chapter of the report, said, "If nations implement the identified sixteen 'tried and true' measures to reduce soot and smog emissions, we could slow warming in the coming decades around the world and even more so in sensitive regions like the Arctic. The measures in the report provide a road map to reducing the risk of irreversible changes with global impacts like ice and permafrost melt and resulting sea level rise that would release of methane and CO2. These measures to reduce black carbon and ground-level ozone emissions are already in use and have been successfully implemented in countries around the world. The challenge now is the scaling up of implementation quickly in the coming years."

Additionally, big cuts in emissions of black carbon will improve respiratory health; reduce hospital admissions and days lost at work due to sickness. Close to 2.5 million premature deaths from outdoor air pollution could on average be avoided annually world-wide by 2030 with many of those lives saved being in Asia, it is estimated.

Reductions in ground level ozone could also contribute to reduced crop damage equal to between one to four percent of the annual global corn, rice, soy bean and wheat production.

Cutting these so-called 'short-lived climate forcers' can have immediate climate, health and agricultural benefits, the report concludes. This is because, unlike carbon dioxide (CO2) which can remain in the atmosphere for centuries, black carbon, for example, only persists for days or weeks.

The researchers however also underline the fact that while fast action on black carbon and ground level ozone could play a key role in limiting near-term climate, immediate and sustained action to cut back CO2 is crucial if temperature rises are to be limited over the long-term.

It is the combination of action on short-lived climate forcers and long-lived greenhouse gases which improves the chances of keeping below the 2 degree target throughout the 21st Century.

The findings, released today in Bonn, Germany during a meeting of the UN Framework Convention on Climate Change (UNFCCC) have been compiled by an international team of more than 50 researchers chaired by Drew Shindell of the National Aeronautics and Space Administration (NASA).

Achim Steiner, UN Under-Secretary General and UNEP Executive Director, said: "There are now clear, powerful, abundant and compelling reasons to reduce levels of pollutants such as black carbon and tropospheric ozone along with methane: their growing contribution to climate change being just one of them."

The UNEP/WMO Integrated Assessment of Black Carbon and Tropospheric Ozone suggests that action could be catalyzed through not only the UN climate convention process but also via, for example, strengthening existing national and regional air quality agreements.

Resources:

• The summary for decision makers and full UNEP/WMO Integrated Assessment of Black Carbon and Tropospheric Ozone report can be found at https://unep.org
• The UN Climate Change Conference, June 2011: https://unfccc.int/2860.php
• UNEP press release