Fast action on black carbon, ozone and methane could help limit global temperature rise to 2 degrees C
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 2 °C (3.6 °F)—and perhaps even 1.5 °C (2.7 °F), according to a new assessment released today in Bonn, Germany, during a meeting of the UN Framework Convention on Climate Change (UNFCCC).
The researchers however also emphasize 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.
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, said assessment authors including Veerabhadran Ramanathan, a climate and atmospheric scientist at Scripps Institution of Oceanography, UC San Diego.
Fast action might also reduce losses of mountain glaciers linked in part with black carbon deposits while reducing projected warming by two thirds in the Arctic over the coming decades by two thirds.
The proposed measures for reducing black carbon, methane and ozone levels in the atmosphere significantly increase our chances to keep global warming below dangerous levels during this century. Some of the measures, such as improved cookstove technologies and cutting down diesel emissions of black carbon also have the fantastic co-benefit of reducing one million or more fatalities every year among women and children.—Veerabhadran Ramanathan, a vice chair of the assessment team
The findings were compiled by an international team of more than 50 researchers chaired by Drew Shindell of the National Aeronautics and Space Administration (NASA). 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.
|Measures that improve climate change mitigation and air quality and have a large emission reduction potential|
|Extended pre-mine degasification and recovery and oxidation of CH4 from ventilation air from coal mines||Extraction and transport of fossil fuel|
|Extended recovery and utilization, rather than venting, of associated gas and improved control of unintended fugitive emissions from the production of oil and natural gas|
|Reduced gas leakage from long-distance transmission pipeline|
|Separation and treatment of biodegradable municipal waste through recycling, composting and anaerobic digestion as well as landfill gas collection with combustion/utilization||Waste management|
|Upgrading primary wastewater treatment to secondary/tertiary treatment with gas recovery and overflow control|
|Control of CH4 emissions from livestock, mainly through farm-scale anaerobic digestion of manure from cattle and pigs||Agriculture|
|Intermittent aeration of continuously flooded rice paddies|
|BC measures (affecting BC and other co-emitted compounds)|
|Diesel particle filters for road and off-road vehicles||Transport|
|Elimination of high-emitting vehicles in road and off-road transport|
|Replacing coal by coal briquettes in cooking and heating stoves||Residential|
|Pellet stoves and boilers, using fuel made from recycled wood waste or sawdust, to replace current wood-burning technologies in the residential sector in industrialized countries|
|Introduction of clean-burning biomass stoves for cooking and heating in developing countries|
|Substitution of clean-burning cookstoves using modern fuels for traditional biomass cookstoves in developing countries|
|Replacing traditional brick kilns with vertical shaft kilns and Hoffman kilns||Industry|
|Replacing traditional coke ovens with modern recovery ovens, including the Industry improvement of end-of-pipe abatement measures in developing countries|
|Ban of open field burning of agricultural waste||Agriculture|
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 worldwide by 2030 with many of those lives saved being in Asia, it is estimated. Big cuts in ground level ozone could also contribute to reduced crop damage equal to between one to four percent of the annual global maize, rice, soybean and wheat production.
Cutting these 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, persists only for days or weeks.
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.
This report has brought clarity to the complexity of the heating and cooling effects of a range of pollutants and uses the science to show that there are clear and concrete measures that can be undertaken to help protect the global climate in the short to medium term. Perhaps the most intriguing link is between emissions of methane and the formation of tropospheric ozone. Methane is a powerful greenhouse gas in its own right, but it has emerged that it is also triggering a great deal more global warming by contributing to the formation of significant levels of ground level ozone-indeed more than was previously supposed. The win-win here for limiting climate change and improving air quality is self-evident and the ways to achieve it have become far clearer as a result of this assessment.—Drew Shindell, NASA’s Goddard Institute for Space Studies
The Government of Sweden announced support for a comprehensive and forward-looking policy assessment to assist governments on the next steps towards fast action on short-lived climate forcers (SLCFs). This is in line with Sweden’s strategy on SLCFs and its policy to integrate climate change and air pollution policies. The work, to be coordinated by UNEP, is expected to be ready in advance of the next Climate Convention meeting scheduled later in the year in Durban, South Africa.