In their recent paper on how to avoid dangerous climate change, Y. Xu and V. Ramanathan suggest the following three-lever strategy to keep global warming within 1.5°C by 2100 (relative to 1900):

  1. Quicker pace of energy efficiency improvements may reduce CO2 warming by 0.9 °C from 3.5 to 2.6 °C of pre-industrial levels.
  2. Maximum deployment of current technologies to reduce emissions of short-lived climate pollutants may reduce warming by another 1.2 °C.
  3. Carbon extraction and sequestration of CO2 to thin the atmospheric CO2 blanket already enveloping our planet.

This post will the first of many addressing the second lever: reduce emissions of short-lived climate pollutants (SLCPs). The main SLCPs are black carbon, methane, tropospheric ozone, and some hydrofluorocarbons. A bit more detail on these SLCPs, care of the Climate and Clean Air Coalition:

  • Black carbon is a major component of soot and is produced by incomplete combustion of fossil fuel and biomass.
  • Methane is produced through natural processes (i.e. the decomposition of plant and animal waste), but is also emitted from many man-made sources, including coal mines, natural gas and oil systems, and landfills.
  • Tropospheric or ground level ozone is not directly emitted but formed by sunlight-driven oxidation of other agents, such as methane, carbon monoxide, and nitrogen oxides. Tropospheric ozone is a major component of urban photochemical smog.
  • Hydrofluorocarbons are synthetic, powerful greenhouse gases that are emitted from a variety of mostly industrial sources, such as air conditioning, refrigeration, solvents, and aerosols.

We will tackle these SLCPs, one at a time - starting with black carbon.

Next: Mitigating black carbon.

References:

Xu, Y. and V. Ramanathan (2017). "Well below 2 ° C: Mitigation strategies for avoiding dangerous to catastrophic climate changes." Proceedings of the National Academy of Sciences 114(39): 10315-10323. http://www.pnas.org/content/114/39/10315.full