That’s the threshold beyond which scientists say the effects of global warming—including worsening floods, droughts, wildfires, and ecosystem collapse—will grow considerably. Humans have already heated the planet by an average of 1.1 degrees Celsius since the 19th century, largely by burning fossil fuels for energy, scientists say.
But the task is daunting: Holding warming to just 1.5 degrees Celsius would require nations to collectively reduce planet-warming emissions roughly 43 percent by 2030 and to stop adding carbon dioxide to the atmosphere altogether by the early 2050s, the report found. By contrast, current government policies are expected to reduce global emissions by only a few percentage points this decade.
“This is a climate emergency,” says U.N. Secretary-General António Guterres.
In the coming decades, as global temperatures continue to rise, hundreds of millions of people could struggle against floods, deadly heat waves, and water scarcity from severe drought, the report says. Mosquitoes carrying diseases like dengue and malaria will spread to new parts of the globe. Crop failures could become more widespread.
The report, which lays out strategies that countries could pursue to halt global warming, comes as Russia’s invasion of Ukraine has caused oil and gas prices to skyrocket, diverting political attention from climate change. In the U.S. and Europe, leaders are focused on shoring up domestic fossil fuel supplies to avoid price spikes and energy shortages, even if that means higher short-term emissions.
Yet climate scientists say there is little room for delay if the world wants to hold warming to relatively tolerable levels.