The United Nations warned Wednesday that the world will miss the Paris Agreement's 1.5°C warming limit, urging a focus on limiting "overshoot" and eventually reversing temperature rise. Despite growth in wind and solar, continued burning of oil, gas, and coal has raised global temperatures by about 1.4 degrees Celsius. The 141-page U.N. report states that breaching 1.5°C is certain and outlines a difficult path requiring massive carbon dioxide removal — potentially through vast reforestation or unproven technologies. Even under this scenario, temperatures would keep rising for decades, and changes like glacial melting would be irreversible. "This is by no means an acceptable or preferred pathway," the U.N. said. "It is simply the best remaining option."

Current policies put the planet on track for 2.6 degrees Celsius of warming by 2100. The Trump administration has withdrawn the United States, the largest historical emitter, from global climate efforts. To return to 1.5°C this century, peak warming must stay below 1.8 Celsius, a threshold most scientists deem unlikely. Michael Mann of the University of Pennsylvania warned that "dangerous and catastrophic climate change is here," citing a deadly glacial collapse in Nepal. António Guterres, the U.N. secretary general, previously acknowledged the 1.5°C mark would be breached. Glen Peters of the CICERO Center for International Climate Research noted reforestation would require land larger than entire American states.