Record year for CO2 makes Paris goals harder to reach
China drives a resurgence in pollution of heat-trapping gas
People are pumping more carbon dioxide into the atmosphere than ever before.
An estimated 37 billion metric tons of CO2 will be released this year, 2 percent more than 2016 and marking an end to a three-year hiatus in pollution growth driven by less-wasteful energy use that had given many people hope emissions had peaked. The CO2 resurgence was caused mostly by China, which saw a rise in coal, oil, and gas use this year.
The finding, issued by an international team of scientists, comes as diplomats in Bonn this week etch details into the 2015 United Nations Paris climate agreement.
The Global Carbon Project published articles simultaneously in three journals on Monday: a detailed overview of their work in Earth System Science Data, a short analysis of how dangerous rising emissions are in Environmental Research Letters, and a call for more nimble monitoring of the Earth’s carbon flows in Nature Climate Change.
"We should already be reducing global emissions so they can reach zero in time to keep climate change under control," said Corinne Le Quéré, professor of climate change science and policy at the University of East Anglia and the main study’s lead author. "Every year that emissions increase means we either have to reduce emissions more later or we will have higher levels of climate change."
When deforestation is accounted for, 2017 should tie the 2015 CO2 record of about 41 billion metric tons of carbon dioxide released.
China, the largest national polluter, is responsible for 28 percent of the total. The U.S., the second-biggest emitter, at 15 percent, has lowered its emissions rate by about 1.2 percent annually for a decade. This year, that braking has slowed down to minus-0.4 percent, on increases in oil and coal use. American coal consumption is expected to rise for the first time in five years, by about 0.5 percent.
Carbon makes up only .04 percent of the atmosphere but is a powerful heat-trapping gas and is the dominant cause of the rise in global temperatures. The five hottest years on record have happened since 2010, and 16 of the hottest 17 have occurred since 2000.
The studies aren’t devoid of positive news. Twenty-two countries -- making up a fifth of overall emission -- enjoyed both economic growth and lower emission rates in the last decade. In the U.S., politicians supportive of climate policy follow that trend, as a possible foil to their opponents, who say that new energy systems may harm national growth. Emission rates are not expected to return to those observed in the 2000s, when developing nations rapidly industrialized.
Scientists assigned the Global Carbon Project a tricky task when they formed it 16 years ago: answering the question "where does the carbon go?"
It’s no secret where CO2 heads once it leaves a smokestack or tailpipe. It goes up. Once it’s there, measuring the global average CO2 average is pretty easy. The U.S. has been doing it almost continuously since 1958, a period that has seen the level steadily rise by 31 percent.
From there, complexity blossoms. The apparently smooth global rise of CO2 every year veils a turbulent and unpredictable planetary carbon cycle. Oceans and land every year absorb on average half of humanity’s climate pollution, with wild variability. Some years as little as 20 percent of emissions vanish into the Earth, some years as much 80 percent.
Understanding the Earth’s “carbon budget” is the Global Climate Project’s mission. Its scientists estimate how it flows among five major sources and “sinks,” or areas that absorb carbon: industrial emitters, emissions from gutting forests and other changes to land, the atmosphere itself, oceans, and land.
This seemingly arcane Earth science research is critical to the practical future of the Paris Agreement. Nations supportive of the pact, which includes all but the U.S., need more advanced tools and practices to measure their own progress, or lack thereof, and to gauge how ongoing pollution is changing the composition of the entire biosphere.
The longer nations wait, the more they will have to slash emissions, wrote Robert Jackson, a Stanford University earth science professor, and six colleagues in Environmental Research Letters.
“Nothing short of deep and rapid decarbonization,” they state, in the terse, scientific-journal equivalent of a full-throated scream, “will keep the Earth from surpassing the 1.5 degree Celsius average temperature threshold in as little as a decade, and 2 degree Celsius a few decades after that.”