It’s clear global warming will have a major impact on Europe, but there may be climate demons lurking that scientists are much less certain about. A POLITICO review of the latest climate science, including a draft of a major new report from the U.N. Intergovernmental Panel on Climate Change, offers a troubling vision of the future for Europe and the wider world, even under temperature rises that are practically inevitable. But while scientists are increasingly confident of these findings, there are still phenomena and potential impacts that are relatively understudied or harder to predict. We asked some leading scientists to give a sense of the nagging impacts they fear, but don’t fully understand.