The oceans of the Pale Blue Dot are going to be a lot less hospitable to coral reefs and other marine life by the end of the century. That’s one of the worrying conclusions from a new expert report that summarizes problems from increasing acidity. Marine waters are becoming more acidic as they continue to absorb carbon dioxide from the atmosphere. This will alter ocean chemistry and make it harder for corals to build their skeletons out of a mineral called aragonite. Corals prefer a saturation state greater than 3 (dark blue on map). Researchers have “high confidence” that coral reefs in the tropics are going to get eroded faster than they will build up, according to the report. But the team admits that in many situations, it’s hard to know exactly the scale or extent of the damage. The document, published by the International Geosphere-Biosphere Programme, is intended to inform negotiations at the meeting of the United Nations Framework Convention on Climate Change in Warsaw.