Teeming tropical seas face exodus to cooler water

Organisms like these marine sea slugs must adapt to new temperatures or move to new areas to stay in the same ones. Image courtesy of Hugh Brown, Scottish Association for Marine Science

Though oceans are warming more slowly than land on average, climate changes still put sea creatures under similar pressure to those on dry land. That’s what Michael Burrows from the Scottish Marine Institute in Oban and 18 other researchers from eight different countries found by analysing the world’s surface temperature over the past 50 years. They brought together rates and directions of temperate change into a measure called “velocity of climate change”, showing how quickly and far species would have to move to stay in a similar environment. “It so happens that there are an awful lot of species in some of the places where velocities are highest, especially in the tropical oceans,” Burrows told Simple Climate. “That may have damaging effects on the richness of species in those places, especially in the hottest places, where there can be no immigrants from even hotter places to replace those that leave.”

The team from the "Towards understanding marine biological impacts of climate change" project that produced this work. Michael Burrows is on the left hand side of the middle row. Credit: University of California, Santa Barbara

These findings are the outcome of a series of meetings the researchers held at the University of California, Santa Barbara to assess the evidence for ocean life responding to climate change. “It struck us right away that there were no expectations available for how far organisms should shift to track temperatures, or by how much earlier or later they should do things seasonally,” Burrows explained. “We thought we could analyse temperature data to make these predictions.” Once they decided to do the analysis, it was surprisingly easy, the ecologist said, as worldwide temperature data is already available for the 20^th century and up to the present.