As climate negotiators from around the world meet in Poland this week and next to figure out how to keep greenhouse gases out of the atmosphere, they are hearing some discouraging news: Emissions of the biggest pollutant, carbon dioxide, are going up.
For three years — 2014 through 2016 — the amount of atmospheric CO2 had leveled off. But it started to climb again in 2017, and is still rising.
"Last year, we thought, was a blip — but it isn't," says Rob Jackson, a climate scientist at Stanford University in California.