Coral reefs in the eastern Pacific Ocean stopped growing for 2,500 years, probably because of a change in climate four millennia ago.

Credit: Lauren Toth

Lauren Toth at the Florida Institute of Technology in Melbourne and her colleagues extracted a 2.68-metre core from a reef in the Gulf of Panama (pictured), representing 6,750 years of growth. They analysed the chemical composition of 133 skeletons of Pocillopora corals in the sample to assess coral health, local temperature, ocean currents and rainfall. They found that roughly 4,100 years ago, cooler temperatures and greater rainfall — similar to today's La Niña weather systems — were associated with the beginning of a 2,500-year pause in coral growth. The health of the corals seems to have declined at the start of this hiatus.

The samples also suggest that temperature is a key factor affecting coral growth.

Nature Clim. Change http://dx.doi.org/10.1038/nclimate2541 (2015)