This story was originally published by Grist and is reproduced here as part of the Climate Desk collaboration. Rising temperatures could transform plankton and other tiny aquatic organisms into a huge source of carbon emissions, a little-known—and potentially catastrophic—climate tipping point that could accelerate global warming. A study, published Thursday in Functional Ecology, found that rising temperatures cause a sudden shift in these microbes’ eating habits, flipping them from carbon absorbers to carbon emitters. No one knows just how much carbon these microorganisms could release, and this tipping point hasn’t yet been considered in climate models.