Cutting Lesser Known Pollutants Could Also Curb Climate Change
April 15, 2013

Cutting Other Pollutants, Not Just CO2, Could Curb Climate Change

Brett Smith for - Your Universe Online

While much of the debate surrounding climate change has centered on the reduction of carbon dioxide emissions, a new study in Nature Climate Change found that reducing the emissions of other greenhouse gases could have a profound influence on one of the major knock-on effects of climate change: sea level rise.

As glaciers around the Earth´s polar regions melt due to higher temperatures, they are expected to contribute substantial amounts of water to the oceans. The resulting rise in sea levels would threaten coastal ecosystems and trillions of dollars in property around the planet.

According to the new study, which was a collaboration between Scripps Institution for Oceanography and National Center for Atmospheric Research (NCAR), reductions in four key pollutants could slow the rate of sea level rise around 25 to 50 percent. Pollutants like methane, soot, refrigerants, and ozone-forming gases cycle through the atmosphere at a rate of days to decades, while carbon dioxide hangs in the atmosphere for about 100 years.

“To avoid potentially dangerous sea level rise, we could cut emissions of short-lived pollutants even if we cannot immediately cut carbon dioxide emissions,” said lead author Aixue Hu of NCAR in a statement. “This new research shows that society can significantly reduce the threat to coastal cities if it moves quickly on a handful of pollutants.”

“It is still not too late, by stabilizing carbon dioxide concentrations in the atmosphere and reducing emissions of shorter-lived pollutants, to lower the rate of warming and reduce sea level rise by 30 percent,” added co-author Veerabhadran Ramanathan of Scripps.

“The large role of the shorter-lived pollutants is encouraging since technologies are available to drastically cut their emissions.”

Previous research has shown that glacial melt has caused the world´s sea levels to rise by about 0.1 inches annually in recent years. According to reports by the Intergovernmental Panel on Climate Change and the US National Research Council, sea levels are projected to rise between 7 inches and 6 feet this century if the current trends continue.

With the regulation of carbon dioxide emissions being a hot-button topic politically, the researchers decided to investigate the potential impact of reducing other potentially less controversial pollutants such as soot.

To investigate the other emissions, researchers used the two computer systems, including the NCAR-based Community Climate System Model, to simulate climate, carbon and geochemistry interactions. They also calculated estimates of future emissions of greenhouse gases under a wide range of social and economic scenarios.

The analysis found a large potential for the mitigation of sea level rise, assuming that society reduces emissions of the four gases and particles by 30 to 60 percent over the next several decades.

"Without diminishing the importance of reducing carbon dioxide emissions in the long term, this study shows that more immediate gains from shorter-lived pollutants are substantial,” said co-author Claudia Tebaldi of Climate Central. “Cutting emissions of those gases could give coastal communities more time to prepare for rising sea levels.”

“As we have seen recently, storm surges in very highly populated regions of the East Coast show the importance of both making such preparations and cutting greenhouse gases,” she added.