If world leaders don’t take unprecedented action to reduce greenhouse gases, nearly all aspects of human existence will be threatened by  the “severe,” “pervasive,” and possibly “irreversible,” impacts of climate change. That’s according to a blockbuster new report by the United Nations’ International Panel on Climate Change, which lays out the devastating consequences of a warmer planet. The effects of climate change are already being felt, but, as the report warns, things are about to get much, much worse.

That will be especially true for those living in the world’s poorest countries because higher temperatures will further threaten food and water supplies. According to the report, “throughout the 21st Century, climate-change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security, and prolong existing and create new poverty traps, the latter particularly in urban areas and emerging hot spots of hunger.” These changes could lead to massive destabilization and conflict across the globe.

“Thirty years ago, the previous generation maybe was damaging our atmosphere [and] the earth out of ignorance,” said Michel Jarraud, Secretary-General of the World Meteorological Organization at a recent conference in Japan. “Now ignorance is no longer a good excuse.” In the United States at least, the Obama administration continues to call for action on climate change. “Read this report and you can’t deny the reality,” said Secretary of State John Kerry in Paris this week. “Unless we act dramatically and quickly, science tells us our climate and our way of life are literally in jeopardy. Denial of the science is malpractice.” The sickness has been diagnosed over and over; but it’s still not clear if the world’s most powerful have the will to treat it.