Science: Extreme rains supercharged by warming

Science has just published, “Atmospheric Warming and the Amplification of Precipitation Extremes” (subs. req’d). It concludes:

Here, we use satellite observations and model simulations to examine the response of tropical precipitation events to naturally driven changes in surface temperature and atmospheric moisture content. These observations reveal a distinct link between rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods. Furthermore, the observed amplification of rainfall extremes is found to be larger than predicted by models, implying that projections of future changes in rainfall extremes due to anthropogenic global warming may be underestimated.

In short, global warming is going to make extreme weather even more extreme than scientists have thought. And this conclusion is based largely on observational evidence:

The study team analyzed satellite images of rainfall over tropical oceans over nearly two decades, from 1988 to 2004….This is something that climate models had predicted,” [coauthor Richard] Allan said. “But getting the data from observations is very important”….For every 1.8 degree Fahrenheit (1 degree Celsius) rise in global temperature, heavy rain showers became more common, with most intense category jumping 60 percent.

Remember that on our current emissions path, we are headed towards 5°C warming in this century alone (see “Is 450 ppm politically possible? Part 0: The alternative is humanity’s self-destruction”), which suggests we are headed for a staggering increase in intense rainfall. This has huge implications for both agriculture and human health:

With intense rains, “you can get flash flooding, and heavy rainfall can destroy crops,” [Allan] said. “Those are the most immediate impacts.”

Coupled with rising global temperatures, more frequent and intense rainfall has “major implications for infectious diseases,” said Paul Epstein, a tropical disease expert at Harvard Medical School in Boston, Massachusetts.

“After floods one often sees clusters of vector-borne diseases — malaria, dengue fever, Japanese B encephalitis,” Epstein said.

Floods often cause a jump in cholera and other water-borne diseases, as well as plague and other rodent-borne diseases, he added.

The fact that the climate appears to be changing faster than the models suggested, and that the models underestimate likely climate impacts, is no surprise to Climate Progress readers (see “Are Scientists Overestimating — or Underestimating — Climate Change, Part II”). The media can try to downplay the connection between climate and extreme weather, but the science is quite clear that this impact has already begun and that it has serious consequences for human health and well-being.