Warming is existential.

The world is likely to pass a dangerous temperature threshold within the next 10 years, pushing the planet past the point of catastrophic warming — unless nations drastically transform their economies and immediately transition away from fossil fuels, according to one of the most definitive reports ever published about climate change. The report released Monday by the U.N. Intergovernmental Panel on Climate Change (IPCC) found that the world is likely to surpass its  — limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial temperatures — by the early 2030s.

Beyond that threshold, scientists have found, climate disasters will become so extreme that people will not be able to adapt. Basic components of the Earth system will be fundamentally, irrevocably altered. Heat waves, famines and infectious diseases could claim millions of additional lives by century’s end.

Human activities have already transformed the planet at a pace and scale unmatched in recorded history, the IPCC said, causing irreversible damage to communities and ecosystems. Yet global emissions continue to rise, and current carbon-cutting efforts are wildly insufficient to ward off climate catastrophe.

Monday’s assessment synthesizes years of studies on the causes and , leading U.N. Secretary General António Guterres to demand that developed countries such as the United States eliminate carbon emissions by 2040 — a decade earlier than the rest of the world.

With few nations on track to fulfill their climate commitments and with the developing world already suffering disproportionately from climate disasters, he said, rich countries have a responsibility to act faster than their low-income counterparts.