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Environment Programme and World Meteorological Organization estimate that an aggressive SLCP reduction strategy could prevent 15 - 90 million pre-mature deaths through 2040 due to improved air quality alone. Millions of additional premature deaths would be prevented due to reductions in indoor air pollution, for which products of incomplete combustion are again major sources.The decreases in surface ozone resulting from reduced emissions of both methane and products of incomplete combustion lead to substantial increases in agricultural yields. Under the aggressive SLCP strategy examined by the UN, reduced ozone levels would lead to an increase of 30-135 million metric tonnes in total of wheat, rice, maize (corn) and soybeans each year. Given that the World Health Organization estimates that increases in malnutrition will lead to more deaths attributable to climate change than any other cause, increased agricultural yields could have an extremely large benefit for human health as our planet warms. This is especially the case in developing countries where yield increases resulting from SLCP reductions are greatest and where malnutrition is most likely to increase. Enhanced yields would also increase national food security and income to famers, of course.Hence there are many reasons to reduce SLCPs. The only plausible pathways to achieving the 2C temperature target include reductions in both carbon dioxide and SLCPs, making SLCP reductions an essential part of a long-term climate stabilization strategy. If long-term warming was the only goal, however, reductions in SLCPs could be put off for many decades. The urgent need to address SLCPs comes from the millions who would otherwise die early from poor air quality, the toll of the regional climate disruptions and crop yield losses they cause, and their unique ability to slow down near-term climate change. As with Tambora’s eruption, although there is an impact on global mean surface temperature the true impacts on human wellbeing are vastly greater. Thus there are compelling, but distinct, reasons to reduce both SLCPs and carbon dioxide immediately.Fortunately, we know how to reduce SLCPs. Current technology and practices are available and in fact are already in use in some parts of the world. An aggressive SLCP strategy requires accelerating and expanding the adoption of those best practices worldwide. For methane, large emission reduction potential exists in the fossil fuel industry, both in extraction of coal, oil and natural gas (including eliminating methane flaring), and in fixing leaks during the storage and transmission of natural gas. Substantial decreases in methane emissions can also be realized via separation and treatment of biodegradable municipal waste through composting and anaerobic digestion as well as landfill gas capture. In the agricultural sector, emissions can be lowered by use of anaerobic digestion on farms, manure management and intermittent rice paddy irrigation. Products of incomplete combustion can be decreased by emissions controls on diesel vehicles or a switch to electric vehicles, use of clean cookstoves and heat stoves in developing countries and more efficient biomass stoves in developed nations, upgrading from kerosene lightning to modern electric lighting, and improved technology to replace traditional brick kilns and coke ovens. Use of HFCs or HFC replacements that absorb less infrared radiation can greatly lower their warming impact.Above: Dr Drew ShindellTop: SLCP reductions are necessary to improve air quality in cities