Ancient hurricanes
A question central to research on global warming is how warmer temperatures caused by increased greenhouse gases could influence climate. Probing the past for clues about this potential effect, MIT and Yale climate scientists examined the Pliocene period, which began five million years ago and which some consider to be a potential analog to modern greenhouse conditions. They found that hurricanes influenced by weakened atmospheric circulation — possibly related to high levels of carbon dioxide — contributed to very warm temperatures in the Pacific Ocean, which in turn led to more frequent and intense hurricanes. The research indicates that Earth’s climate may have multiple states based on this feedback cycle, meaning that the climate could change qualitatively in response to the effects of global warming.Although scientists know that the early Pliocene had carbon dioxide concentrations similar to those of today, it has remained a mystery what caused the high levels...