"A warming world is transforming some major snowfalls over mountains into
extreme rain, worsening both dangerous flooding like the type that devastated
Pakistan last year as well as long-term water shortages, a new study has found.
Using rain and snow measurements since 1950 and computer simulations for future
climate, scientists calculated that for every degree Fahrenheit the world
warms, extreme rainfall at higher elevation increases by 8.3% (15% for every
degree Celsius), according to a study in Wednesday’s journal Nature
Heavy rain in mountains causes a lot more problems than big snow, including
flooding, landslides and erosion, scientists said. And the rain is not
conveniently stored away like snowpack that can recharge reservoirs in spring
“It is not just a far-off problem that is projected to occur in the future, but
the data is actually telling us that it’s already happening and we see that in
the data over the past few decades,” said lead author Mohammed Ombadi, a
Lawrence Berkeley National Laboratory hydrologist and climate scientist.
As the world has warmed to the brink of the 1.5C (2.7F) internationally agreed
threshold to stem the worst effects of climate change, this study shows “every
degree [Celsius] matters because it comes with an additional 15% increase” in
extreme rain over mountains, Ombadi said. That per-degree rainfall boost in the
mountains is more than twice the increase the rest of the world gets from
warming air holding more water.
The study looked at only the heaviest rains each year over six decades in the
northern hemisphere, finding that as altitude rose, so did the turbocharging of
rain. The biggest increase in rains were noticed at about 10,000ft (3,000
meters). That includes much of the American west, where Ombadi said “it’s very
pronounced”, as well as parts of the Appalachian Mountains. Another big hotspot
in Asia is the Himalayas, Tian Shan and Hindu Kush mountains, with the Alps
About one in four people on Earth live in an area close enough to the mountains
or downhill that extreme rain and flooding would hit them, Ombadi said."
*** Xanni ***
Chief Scientist, Xanadu
Partner, Glass Wings
Manager, Serious Cybernetics