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Since 1st Earth Day, U.S. Temps Marching Upward

Research Report by Climate Central

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It’s been 44 years since the first Earth Day was celebrated in 1970, and since that time, average temperatures have been rising across the U.S. This Climate Central interactive graphic shows a state-by-state analysis of those temperature trends.

Average temperatures across most of the continental U.S. have been rising gradually for more than a century, at a rate of about 0.127°F per decade between 1910-2012. That trend parallels an overall increase in average global temperatures, which is largely the result of human greenhouse gas emissions. While global warming isn’t uniform, and some regions are warming faster than others, since the 1970s, warming across the U.S. has accelerated, previously shown in our report The Heat is On. Since then, every state’s annual average temperature has risen accordingly. On average, temperatures in the contiguous 48 states have been warming at a rate of 0.48°F per decade since 1970, nearly twice the global average. 

Delaware and Wisconsin are tied as the fastest-warming states since 1970, warming at a rate of 0.67°F per decade. Average annual temperatures in the two states are about 3°F warmer than they were 44 years ago. Vermont, New Jersey, and Michigan are warming nearly as fast, and all are warming about twice as fast as the global average. The slowest-warming states are Washington, Georgia, Florida, and Oregon – warming just more than 0.3°F per decade since 1970 — and are on pace with average global temperatures.

For detailed information on individual states, click on any state in the interactive graphic above.

On a regional scale, the fastest-warming areas are the Northeast, Midwest and Southwest, while the Pacific Northwest and Southeast are warming more slowly. Of the lower 48 states, 26 have warmed more than 2°F since 1970, and 16 have warmed more than 2.5°F.

This analysis draws on temperature data collected from the National Climatic Data Center’s Climate at a Glance database, offering an improved technique for regional temperature trend analysis over our earlier report The Heat is On.