Cutting black carbon ‘will not curb climate change’

Reducing emissions of 'short-lived climate forcers' (SLCF) such as black carbon will do very little to keep global warming below two degrees in the long run.

That’s according to a new study published in the Proceedings of the National Academy of Sciences advising Governments to focus on broader carbon dioxide mitigation policies which would also lead to reductions in pollutants such as black carbon. 

Black carbon is a fine particulate matter formed by the incomplete combustion of fossil fuels, biofuels, and biomass.

Particles are emitted directly into the atmosphere where they affect the climate in several ways including: directly absorbing the sun’s light; reducing the reflectivity of snow and ice through deposition; and interacting with clouds, changing the pattern of precipitation.

Some Governments believe that reducing emissions of black carbon, which has a short lifespan compared with CO2, is an effective way to fight climate change in the short-term.

However, the new study questions whether or not such action would limit climate change in the long-term as reducing black carbon from the atmosphere can be done in ways that don’t involve CO2 -such as cleaning up car exhausts and diesel engines.

Emission reductions

Lead author of the paper, Dr Joeri Rogelj, said: “Reducing black carbon will clean up our air and reduce our impact on the climate in the next couple of decades, but we find that it cannot be a substitute for action to stop carbon dioxide emissions. It turns out that reducing black carbon cannot buy us time for putting in place stringent carbon dioxide emission reductions.”

Another of the authors, Dr Michiel Schaeffer, said: “A rapid phase out of carbon dioxide emissions, including eliminating unmitigated coal from our energy mix, remains the single biggest measure for early action on global warming, which would also reduce a large of air pollutants including black carbon.

“This confirms – from a very different perspective – the key finding of a limited carbon budget in the just-published Synthesis Report by the Intergovernmental Panel on Climate Change.”

The study comes as the Intergovernmental Panel on Climate Change (IPCC) publish a report calling for fossil fuels to ‘be phased out by 2100’ and increase the use of renewables from its current 30% share to 80% of the power sector by 2050 to limit climate change.

Lois Vallely

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