A new study has warned that the politically expedient way to mitigate climate change is essentially no way at all, and that only carbon emissions reductions will address the problem.
Among the climate pollutants humans put into the atmosphere in significant quantities, the effects of carbon dioxide (CO2) are the longest-lived, with effects on climate that extend thousands of years after emissions cease.
However, finding a political consensus to act on reducing CO2 emissions has so far proven nearly impossible.
As a result there has been a movement to make up for that inaction by reducing emissions of other, shorter-lived gasses, like methane, hydrofluorocarbons, nitrous oxide, and particulates such as soot and black carbon, all of which contribute to warming as well.
However, a new study by University of Chicago climatologist Professor Raymond Pierrehumbert shows these efforts to be, as he puts it, a delusion.
“Until we do something about CO2, nothing we do about methane or these other things is going to matter much for climate,” he said.
Professor Pierrehumbert is the Louis Block Professor in Geophysical Sciences at UChicago, and holder of the King Carl XVI Gustaf Chair in Environmental Sciences at Stockholm University for 2014-2015.
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rofessor Katherine Freeman, an expert in geosciences at Pennsylvania State University, said Professor Pierrehumbert convincingly showed the benefit and importance of doing everything possible to lower CO2 emissions, and as soon as possible.
She added that every effort should also be made to lower short-lived pollutants like methane as well.
Professor Freeman agrees, however, that this should not distract from the urgent need to stop burning fossil fuels.
She said the basic physics of climate pollutants has been well known for a long time.
The warming effect of methane and other short-lived climate pollutants disappears quite quickly after the pollutants are removed from the atmosphere, CO2, on the other hand, lingers in the atmosphere.
Carbon dioxide levels in the northern hemisphere had surpassed 400 parts per million (ppm) for the first time in history.
According to climate scientists, the global milestone was of “symbolic and scientific significance.”
Michael Jarraud, the secretary-general of the World Meteorological Organisation (WMO), said greenhouse gas levels had been increasing by 2.0ppm every year in the past 10 years.
Mr Jurraud said “time is running out” for this generation to save the planet for the future.
He said the new record for carbon dioxide levels will serve as a “wake-up call” for climate change action.
The study has been published in Annual Review of Earth and Planetary Sciences.
