Sacramento likely will see its fifth straight day of temperatures above 104 degrees on Thursday, an unusually intense heat wave.
Such heat waves will be the norm if greenhouse gas emissions continue to rise over the rest of the century, according to projections by the Scripps Institution of Oceanography at UC San Diego.
Sacramento saw an average of four days each year when temperatures exceeded 104 degrees between 1960 and 2000.
Sacramento will see an average of 40 days each year with temperatures above 104 degrees between 2070 and 2100 if emissions continue to rise strongly through 2050 and plateau around 2100, according to the UC San Diego projections. For comparison, Tucson, AZ, saw about 30 days that hot last year.
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That model predicts that Sacramento will begin to see several days with temperatures above 104 degrees in May and October as soon as the next decade.
A more hopeful scenario assumes the state will cut back emissions so they peak around 2040, then begin to decline. It provides a slightly rosier picture: 28 Sacramento days per year with temperatures over 104 degrees by 2100, with extreme heat in May and October beginning around 2040.
This chart shows the projected number of 100 degree days in Sacramento under the two scenarios. It uses the second generation Canadian Earth System Model, a widely-disseminated climate model developed by the Canadian government.
Data Tracker is a regular feature that breaks down the numbers behind today’s news. Explore more trends at sacbee.com/datatracker.