Short-term fixing of the global climate will not help, says a new interdisciplinary study by showing how long-term emissions of carbon dioxide and short-lived climate pollutants like methane and sulphur dioxide are related.
Soot particles, methane and fluorocarbons originating from fossil fuels, coal mines, cows and diesel engines are called short-lived climate forcers (SLCF) due to their brief lifetime of a few days to a decade.
On the other hand carbon dioxide lasts thousands of years in the atmosphere, trapping heat and warming the planet.
Researchers led by ETH Zurich's climate scientist Joeri Rogelj showed that short-term measures to reduce SLCF had only a minor effect on the long-term rise in temperature, in the scenario of global temperature rise staying below two degrees.
"Stabilizing climate at any temperature means that, at some point, global CO2 emissions have to become zero," says Joeri Rogelj, who led the IIASA (International Institute For Applied Systems Analysis) study.
"Although near-term action on short-lived climate forcers can help reduce warming in the coming decades and also provides other societal benefits, such as cleaner air, it will not buy us time for delaying the reductions in carbon dioxide emissions which are required to stabilize the climate at safe levels."
Governments and industry have been trying to argue for a reduction in SLCF emissions to buy time on the climate change fix.
SLCFs have an impact for only as long as they are generated; once their supply fails, their warming effect soon disappears. Measures to reduce these should be seen as a complement to CO2 reduction measures, not as a replacement, says the researchers.
No benefits in the long-term could be calculated by restriction of methane or fluorocarbon emissions.
So also was the case with soot released in burning fossil fuels. This was so in the two degree limit scenario and was essentially due to the fact that a two degree temperature scenario must anyway cut down on carbon emissions.
As both emissions – carbon dioxide and SLFC – arise from burning fossil fuels, the link is clearly established.
Using the example of a diesel engine that emits both soot and CO2 they argue how a particle filter that removes soot does not do much to mitigate warming as CO2 continues to be emitted while the short-lived soot is removed.
Compared to soot, carbon dioxide stays in the atmosphere for hundreds of years and works cumulatively.
The study is published in the journal Proceedings of the National Academy of Sciences (PNAS) and comes in the wake of the recent IPCC climate assessment study. The IPCC has warned of dire consequences unless the world is weaned away from fossil fuels completely by end of the century and carbon emissions reduced to zero.