For three years in a row, the world's carbon emissions were virtually stable — holding steady after decades of growth.
But now they're on the rise again, which is bad news for efforts to fight climate change, according to a team of researchers who have released a new study on the topic.
Seventy-six scientists from around the world contributed to the Global Carbon Project, or GCP, which released its annual "Carbon Budget" on Monday.
The budget estimates that total global carbon emissions from fossil fuels and industrial sources will rise by 2 percent in 2017. There's a fair amount of uncertainty in that projection, with possible values from .8 percent to 3 percent — but the researchers are confident it represents an overall rise, fueled in part by changes in the Chinese economy.
The anticipated change is a "big rise," lead author Corinne Le Quéré tells NPR. "And this is contrary to what is needed in order to tackle climate change."
It's a shift from the more hopeful findings from the last few years. From 2014 to 2016, according to the GCP analysis, the rate of emissions was basically flat.
"The slowdown in emissions growth from 2014 to 2016 was always a delicate balance, and the likely 2% increase in 2017 clearly demonstrates that we can't take the recent slowdown for granted,"said Robbie Andrew, a senior researcher at CICERO Center for International Climate Research in Oslo and a co-author of the studies, said in a press release.
Scientists agree that a reduction in carbon emissions is necessary to keep the global warming at 2 degrees Celsius or less, the target established by the global accord on climate change (which President Trump intends to withdraw from). That level of climate change is still projected to have a range of damaging effects, including devastation for some island nations — but it will be far from the worse-case scenario projected if emissions continue to rise.
The increase in carbon emissions is not distributed evenly around the world.
The U.S. and the countries of the European Union, which once generated nearly all of the world's fossil-fuel and industrial carbon emissions, now contribute less than half of the world's cumulative emissions. Their contributions are expected to continue to fall in 2017, albeit at a lower rate than they had previously been falling.
Emissions from China, India and the rest of the world, however, are projected to show marked increase in 2017.
The result is "an emissions tug-of-war," as the CICERO Center for International Climate Research put it in a press release.
That makes it hard to tell what's going to happen next, because the trend is "so fragile," as Le Quéré told NPR on Monday.
"It's the difference between emissions rising in parts of the world and decreasing in other parts of the world," she says. Overall? "Frankly, it could really go either way."
And it's crucial for that upward trend to start moving down, and quickly, she says. She points to already-evident consequences of global warming: warmer oceans that can fuel more powerful storms and rising sea levels that cause more devastating coastal surge damage.
"In order to tackle climate change emissions you have to go down to almost zero" emissions, she says. "The faster we do it, the more we limit the risks from climate change."
Six of the study's authors co-wrote an article about their findings in The Conversation; you can read it here.