Out of season

Fifty feet under the Pacific Ocean off the Galapagos Islands, climate scientist Julia Cole, in full scuba gear, searched for an archive of climate that no human-made instrument had ever recorded. Using a pneumatic drill, the Professor of Earth and Environmental Sciences at the University of Michigan extracted pieces of coral — tiny marine animals that build hard limestone skeletons that form coral reefs.

Scientists have known for more than four decades that corals can preserve chemical signatures of the surrounding seawater. Cole descended into the Pacific in 2010 and 2015 and collected dozens of coral samples — both living underwater corals and older fossilised corals from along the islands’ shores — hoping to reconstruct a history of sea surface temperatures in that part of the Pacific over the past 900 years.