Past analogs of projected future climates

A study suggests that as temperatures rise future climates could be analogous to past climates from Earth's deep history. Climates from Earth's deep past may provide analogs for possible near-future climates, but past and projected future climates have not been quantitatively compared. Kevin Burke, John Williams, and colleagues compared mean summer and winter temperatures and precipitation projected for 2020-2280 CE to those from two historic and four prehistoric warm periods spanning the last 50 million years. The authors found that Mid -Pliocene climates, 3.3-3 million years ago, replaced historical precedents as the best analog for future climates after 2030 CE. Under a scenario in which greenhouse gas emissions stabilize by the mid-21st century, Earth's projected climate stabilized at Pliocene-like conditions. Under an unmitigated emissions scenario, global climates began to resemble those of the Early Eocene, 50 million years ago, by 2150 CE. In the latter scenario, up to 9% of projected climates had no close analog among any of the past climates examined. Both Pliocene-like and Eocene-like climates emerged initially in the continental interiors and subsequently spread outward. Hence, the results suggest that unmitigated greenhouse gas emissions may result in the reversal of a 50-million-year cooling trend in two centuries, according to the authors.

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Article #18-09600: "Pliocene and Eocene provide best analogs for nearfuture climates," by Kevin D. Burke et al.

MEDIA CONTACT: Kevin D. Burke, University of Wisconsin-Madison, WI; e-mail: kdburke@wisc.edu; John W. Williams, University of Wisconsin-Madison, WI; tel: 608-265-5537; e-mail: jwwilliams1@wisc.edu