Increased greenhouse gases and aerosols have similar effects on rainfall

Sep 01, 2013
Image: Wikipedia.

Although greenhouse gases and aerosols have very distinct properties, their effects on spatial patterns of rainfall change are surprisingly similar, according to new research from the University of Hawaii at Manoa's International Pacific Research Center (IPRC) and Scripps Institution of Oceanography. The study is published in the September 1 online issue of Nature Geoscience.

Manmade climate change comes mostly from the radiative forcing of greenhouse gases and or . While greenhouse gases are well-mixed in the atmosphere and tend to be evenly distributed around the globe, aerosols vary greatly in local concentration and tend to be found near emission sources such as industrial centers in Asia and North America.

Aerosols affect climate in two ways: one is fast and perturbs the physics and behavior of clouds in minutes to days; the other effect takes years and is mediated by interactions with the ocean and atmosphere. The fast effects of aerosols on clouds have been studied intensely, but their long-term ocean-mediated effect has received little attention.

A team of scientists at the IPRC and Scripps has now provided important new insights based on results from experiments with three state-of-the-art . Even though aerosols and greenhouse gases are concentrated in vastly different regions of the earth, all three models revealed similar regional effects on rainfall over the ocean.

"This came as a big surprise to us," reflected lead-author Shang-Ping Xie, a professor of and first Roger Revelle Chair in Environmental Science at Scripps. "It took a while for the result to sink in. The result means that it is hard to tell apart the greenhouse and aerosol effects."

The scientists noted that both aerosol-induced and greenhouse-gas-induced changes in rainfall appear to be mediated by the spatial patterns of .

"Although much of the aerosol research has focused on microphysical processes, over the ocean the climate response to aerosols appears to be insensitive to details of the micro-processes in clouds," Xie said. "The climate changes induced by and by aerosols share a common set of ocean-atmospheric feedback structures, explaining the spatial resemblance between the two types of response."

"Innovative model experiments are now needed," says coauthor Baoqiang Xiang, postdoctoral fellow at the IPRC. We want to probe the ocean-atmosphere interaction mechanisms that mediate these rainfall patterns and to determine what forms the foundation. This will allow us to develop more reliable regional projections."

Explore further: Rapid upper ocean warming linked to declining aerosols

More information: Xie, S.-P., B. Lu, and B. Xiang: Similar spatial patterns of climate responses to aerosol and greenhouse gas changes. Nature Geoscience, DOI: 10.1038/ngeo1931. Advance Online Publication: September 1, 2013. DOI: 10.1038/ngeo1931

Related Stories

Rapid upper ocean warming linked to declining aerosols

Jul 23, 2013

They partly attribute the observed warming, and preceding cooling trends to ocean circulation changes induced by global greenhouse gas emissions and aerosols predominantly generated in the Northern Hemisphere from human activity.

Aerosols -- their part in our rainfall

Feb 12, 2009

Aerosols may have a greater impact on patterns of Australian rainfall and future climate change than previously thought, according to leading atmospheric scientist, CSIRO's Dr. Leon Rotstayn.

Recommended for you

Magnitude-7.2 earthquake shakes Mexican capital

13 hours ago

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.

User comments : 0

More news stories

Magnitude-7.2 earthquake shakes Mexican capital

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.

New research on Earth's carbon budget

(Phys.org) —Results from a research project involving scientists from the Desert Research Institute have generated new findings surrounding some of the unknowns of changes in climate and the degree to which ...

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...