Extreme heat caused by the “super” El Niño currently brewing in the Pacific Ocean could cause nearly half a million deaths by the end of February.

The estimate, described in a report released in September by the University of Chicago’s Climate Impact Lab, found that people living in the Global South will be hardest hit. Although the work has not been peer-reviewed, the authors say their findings are urgent enough to publicize prior to formal publication. They plan to submit it to a scientific journal, and in the meantime, they hope that it can guide humanitarian and government decisions in the coming months to avoid some of the predicted deaths.