Nature & Environment

Global Precipitation Changes Linked to Warming Climate

Catherine Griffin
First Posted: Nov 12, 2013 09:41 AM EST

It turns out that precipitation patterns may be changing across the globe as our climate warms. Scientists have discovered that human activities may be the cause for observed changes in precipitation across the world since it cannot be explained by natural variability alone.

In order to learn a little bit more about what might be causing the shift in precipitation patterns, the researchers compared climate model predictions with the Global Precipitation Climatology Project's global observations, which span from 1979 to 2012. In the end, the scientists found that natural variability does not account for the changes in global precipitation patterns. While natural fluctuations can either lead to an intensification or poleward shift in precipitation, it's very rare for both to occur together naturally.

"Both these changes are occurring simultaneously in global precipitation and this behavior cannot be explained by natural variability alone," said Kate Marvel, lead author of the new study, in a news release. "External influences such as the increase in greenhouse gases are responsible for the changes."

In fact, manmade increases in greenhouse gases and stratospheric ozone depletion are expected to lead to both an intensification and redistribution of global precipitation. The fact that both of these effects are occurring simultaneous is strong evidence that humans are impacting global precipitation.

"Most previous work has focused on either thermodynamic or dynamic changes in isolation," said Marvel in a news release. "By looking at both, we were able to identify a pattern of precipitation change that fits with what is expected from human-caused climate change."

By focusing on the underlying mechanisms that drive changes in global precipitation and by restricting the analysis to the large scales where there is confidence in the models' ability to reproduce the current climate, the scientists were able to show that the changes are likely manmade. This is huge when it comes to the current discourse concerning climate change. The findings reveal that it's necessary to take action in order to help curtail the current changes.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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