Thread by @PeterGleick

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Water Thread from the new National Climate Assessment (#NCA4).

Explicit changes in water quantity & quality from human-caused climate change are already evident in the US.

Source: #NCA4, Chapter 3: Water. nca2018.globalchange.gov/chapter/3/

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Changes in the frequency & intensity of climate extremes are already underway. Climate change is already leading to changes in the frequency, duration, & geographic distribution of severe storms, floods, & droughts. #water #climate #NCA4

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Variable precipitation & rising temperature are intensifying droughts, increasing heavy downpours, & reducing snowpack.
Reduced snow-to-rain ratios are affecting the timing of both water supply & demand.
#water #climate #NCA4

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Groundwater depletion is worsening the consequences of drought. Surface #water quality is declining as water temperatures rise & more frequent high-intensity rainfall events mobilize pollutants. Glaciers continue to melt in Alaska & the western United States.
#climate #NCA4

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Increasing air temperatures have substantially reduced the fraction of winter precipitation falling as snow, particularly over the western United States. Warming has resulted in a shift in the timing of snowmelt runoff to earlier in the year.
#water #climate #NCA4

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Heavy precipitation events in most parts of the United States have increased in both intensity & frequency since 1901 & are projected to continue to increase over this century under both a lower & higher emissions scenario, raising flood risks.
#water #climate #NCA4

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Higher temperatures are leading to an increased human use of #water, particularly through higher water demand for agriculture by increase evapotranspiration, threatening farmers and food production.
#climate #NCA4