Emerging climate trends are projected to increase the risk of extreme flooding in parts of the U.S. as well as reduce snowpack in many regions of the Northern Hemisphere.

An analysis of historical trends in annual maximum discharge for the 1985 to 2014 period and implications for future flood events occurring during 2071 to 2100 in the contiguous U.S. was conducted by Princeton University researchers. Past seasonal temperature and precipitation data were modeled to estimate changes in regional flooding under different scenarios to assess likely climate change-driven changes in these factors.

The study published in Nature Communications points to a stronger and more detectable signal of change with increasing greenhouse gas emissions. The forecast: increased flooding in the northeastern and southeastern U.S., particularly along the eastern seaboard. Flooding will generally decline in the southwest and the Northern Great Plains.

Reductions in snowpack are already evident throughout the Northern Hemisphere, as reported by Dartmouth College researchers in Nature. Snowpack, temperature, precipitation and runoff data for the 1981 to 202 period were examined with empirical and climate models to attribute snowpack changes to anthropogenic warming at the hemispheric and river-basin scales.

Findings underscore serious water-availability challenges in basins where snowmelt runoff constitutes a major component of water supply. The loss of snowpacks translates into less meltwater in spring for rivers, streams, and soils downstream. The most pronounced global warming-related reductions in snowpack of 10% to 20% per decade are identified in the southwestern and northeastern U.S., as well as in Central and Eastern Europe.

To contact the author of this article, email shimmelstein@globalspec.com