Scientists have published a major new paper warning climate change could cause catastrophic storms beyond any seen in modern times and the loss of swaths of the polar ice sheets. While countries around the world have agreed on 2 degrees Celsius of warming above pre-industrial levels as a limit for global warming, the paper warns such a rise would be “dangerous.” The world is already halfway to the 2-degree mark. Former NASA scientist and leading climatologist James Hansen was one of 19 co-authors. He spoke in a video accompanying the report.

James Hansen: “These feedbacks raise questions about how soon we will pass points of no return in which we lock in consequences that cannot be reversed on any time scale that people care about. Consequences include sea level rise of several meters, which we estimate could occur this century or at latest next century if fossil fuel emissions continue at a high level. That would mean loss of all coastal cities, most of the world’s large cities and all their history.”

The report comes after last month shattered climate records, becoming the warmest month in recorded history, surpassing the previous record—set in December.