Reducing Emissions of Soot, Methane Can Decrease Sea-Level Rise

Cutting-down emissions of pollutants such as methane, soot, refrigerants, and gases can help in reducing sea-level rise by 2100, according to a new study.

Researchers said that reducing emissions of these short-lived pollutants could slow-down the annual rise in sea-levels by as much as 25 to 50 percent.

"To avoid potentially dangerous sea level rise, we could cut emissions of short-lived pollutants even if we cannot immediately cut carbon dioxide emissions. This new research shows that society can significantly reduce the threat to coastal cities if it moves quickly on a handful of pollutants," said Aixue Hu of the National Center for Atmospheric Research (NCAR), the first author of the study.

Previous research has shown that reducing levels of soot and methane in the atmosphere is a better strategy to adopt against climate change.

Sea levels are rising at a rate of 3 millimeters (0.12 inches) per year and could rise between 18 and 200 centimeters (between 7 inches and 6 feet) by the end of this century. As most of the world's major cities are located near the sea, rising sea-levels could be disastrous for many people.

In the present study, the research team from Scripps Institution for Oceanography, NCAR, and Climate Central looked at reducing the impact of certain pollutants like methane and soot that are known to trap heat. These pollutants stay in the atmosphere for less time, but influence climate change more quickly than carbon dioxide.

"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. The large role of the shorter-lived pollutants is encouraging since technologies are available to drastically cut their emissions," said Veerabhadran Ramanathan of Scripps, lead author of the study, according to a news release.

The data for the study came from the NCAR-based Community Climate System Model as well as another model that simulates climate, carbon and geochemistry. Researchers also estimated the change in levels of the greenhouse gases under various social and economic scenarios.

The study showed that reducing these four pollutants by 2015 could sharply slow down sea level rise by 50 percent by the year 2050.

"It must be remembered that carbon dioxide is still the most important factor in sea level rise over the long term. But we can make a real difference in the next several decades by reducing other emissions," said Warren Washington, a co-author and an NCAR scientist.

The study is published in the journal Nature Climate Change.