First, some good news. Prior posts have noted repeatedly the key role that methane plays in global warming (the longterm trend in temperature, not seasonal or annual variations). Prior posts have also noted the role that particulates-aerosols play in global warming, and their adverse effect on human health.
Cutting the amounts of methane and "soot" that are poured into the atmospher would diminish warming by half a degree Celsius by 2050, researchers allege. That might buy time for the world to act, by slowing sea level rise, glacial melting, and other problems caused by rising temperatures. Targeting these agents of climate change would also improve air quality, potentially preventing up to 4.7 million premature deaths every year, the researchers believe. Compared to controlling CO2, these strategies are relatively inexpensive.
The researchers found that methane control was a key tool to slow global warming. Implementing controls already being used in various parts of the world would prevent atmospheric loading of methane from coal mines, livestock manure, landfills, and other sources noted in prior posts. Putting filters on cars that burn diesel, for example, could trap the soot which absorbs sunlight and heat the atmosphere. Soot also, as noted previously, darkens snow and glaciers, which hasten their melting. Critics of the latter aspect to the strategy note that some sources of soot also give off particles that reflect sunlight, cooling the planet. Clearly some critical assessment needs to be done.
The report can be found at http://www.sciencemag.org/content/335/6065/183.abstract.
Now the bad news. The increasing use of coal for power generation in China and India, and for that matter across Asia, is likely to lead to a large increase in CO2 emissions. Unfortunately neither solar nor wind will offer affordable electricity on a large enough scale to slow this expansion of coal-fired generation, even with the potential significant increases in efficiency noted in prior posts. It is also unlikely that natural gas will supplant coal in this region.
The International Energy Agency has compared the likely result of this massive increase in coal-fired generation with the goal often put forth of holding global warming to below 2 degrees C this century. Given the plants "in the pipeline" it is likely that enough generating capacity will be online by 2017, believes the IEA, that this goal will not be met.
A discussion of this issue can be found at http://www.economist.com/node/21548237.