Reducing Short-term Climate Pollutants – is it worth it?


22nd November 2013.

A recent report from the World Bank and the International Cryosphere Climate Initiative (ICCI) has detailed the effects of climate change on the cryosphere; areas of the planet that are constantly frozen. These effects include thawing permafrost, melting glaciers, and receding ice sheets, which may stimulate positive feedbacks through albedo changes. The joint report goes on to offer solutions to lower concentrations of short-lived climate pollutants (SLCPs) such as methane and black carbon, with the aim of slowing climate change.

The specific call of the report is to implement fourteen changes by 2030. Seven of these changes target methane and seven target black carbon. A large proportion of the methane strategies are based on capturing emissions from several different sectors, including coal mining, energy production, landfill, wastewater, and livestock. Additionally, there are calls to increase composting and recycling, as well as the suggestion to keep rice paddies continuously flooded so as to restrict emissions. The black carbon strategies include the widespread use of particle filters on diesel engines, and the reduction in both accidental and deliberate (for agricultural and forestry purposes) fires. Black carbon reduction measures also involve the use of biogas and LPG rather than biofuel with cooking stoves, and the incorporation of fans to enhance combustion. With regards to heating stoves, there is the suggestion for a switch from chunk coal to coal briquettes.

The authors hope that, if implemented, these measures will result in numerous benefits to human health, as well as to the climate. For example, the annual death toll due to smoke exposure from cooking stoves is four million, whilst a 50% decrease in the burning of open fields and forest could improve air quality and lead to 190,000 fewer deaths per year.

The report does stress that these fourteen suggested changes are essentially only interim measures to prevent climate change, and that any benefits from them will be nullified without associated reductions in atmospheric carbon dioxide emissions. As Rachel Kyte of the World Bank writes in the report’s foreward: “the science is settled and the problem identified. Now we must act in the smartest and most effective way we can. Our world is on thin ice.”

However, the World Bank and ICCI report is undermined by a new paper published in Nature Climate Change.   In it, the authors show that reductions in SLCPs are essentially futile unless accompanied by decreased emissions of carbon dioxide and nitrous oxide. The authors state that “these arguments serve to reinforce the point — widely accepted in the scientific community but often overlooked in policy discourse — that relative to delayed SLCP reductions, early SLCP reductions cannot be used to buy time to delay reductions in LLCPs (long-lived climate pollutants) such as carbon dioxide.”

The issue of reducing SLCPs thus appears to be complex. Reducing SLCPs does have the potential to bring other benefits to human health, agriculture and ecosystems, as discussed in the World Bank/ICCI report. Additionally, some people hope that lowering SLCPs will be a prudent political move because it might stimulate action to reduce carbon dioxide emissions.   Countering this, there is the possibility that resources targeting SLCPs might be better devoted to reducing LLCPs.

What do you think?

The report can be downloaded here:

Bowerman, N.H.A., Frame, D.J., Huntingford, C., Lowe, J.A., Smith, S.M., Allen, M.R. 2013. The role of short-lived climate pollutants in meeting temperature goals. Nature Climate Change. doi:10.1038/nclimate2034

Image: Mount Everest North Face as seen from the path to the base camp, Tibet. By Luca Galuzzi.