The severe droughts in the USA and Australia are the first sign that the tropics, and their warm temperatures, are apparently expanding in the wake of climate change. But until now, scientists have been unable to conclusively explain the reasons for this, because they were mostly focusing on atmospheric processes. Now, experts at the AWI have solved the puzzle: the alarming expansion of the tropics is not caused by processes in the atmosphere, but quite simply by warming subtropical ocean.
Forest fires in Australia and California, droughts and water shortages in the Mediterranean—in the last few years, events such as these have become more frequent. Researchers attribute this to the fact that the tropics, the warm region surrounding the Equator, appear to be expanding. And that leads to