Strategy outlined to limit global warming

SAN DIEGO, May 10 (UPI) -- U.S. scientists say they've identified three methods nations can use to meet the goal of limiting the increase of global average temperatures.

Major greenhouse gas-emitting countries last December agreed substantial action is required to limit global warming to less than 3.6 degrees Fahrenheit.

In the new study, researchers at the Scripps Institution of Oceanography at the University of California-San Diego identified three avenues by which that goal can be reached.

The scientists -- Veerabhadran Ramanathan and Yangyang Xu -- said exceeding that warming threshold is a point which many experts say likely would trigger irreversible phenomena such as widespread release of methane from melting permafrost and large-scale glacial melt that would exacerbate climate change-related problems, such as sea-level rise and acceleration of global warming.

The first and second recommended steps include stabilizing atmospheric carbon dioxide concentrations and fashioning warming-neutral pollution laws to balance removal of aerosols that have an atmospheric cooling effect with the removal of warming agents such as soot and ozone.

Thirdly, the researchers advocate achieving immediate cooling through reductions in methane, hydrofluorocarbons and other greenhouse gases that last in the atmosphere for short periods of time.

They said simultaneous pursuit of the strategies could reduce the probability of reaching the temperature threshold to less than 10 percent before the year 2050.

The research is detailed in the Proceedings of the National Academy of Sciences.