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Global Emissions Plateaued for Three Consecutive Years. That Doesn’t Mean We Can Relax.

Several recent studies provided a glimmer of hope, but these developments alone won’t halt climate change

Emissions from cars and other forms of transportation is one of the many sources of greenhouse gasses. (Grafissimo/iStock)
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Understanding the intricacies of climate science is no small feat. Mix in politically-motivated doubts, conspiracy theories and a steady drumbeat of positive and negative news headlines, and the waters grow increasingly muddy. This past week two studies in particular have provided a glimmer of hope on the climate change front, but these developments alone won't halt the the destructive march of carbon emissions.

The first study, published in the journal Earth System Science Data, shows that global emissions have leveled out over the last three years, reports Chris Mooney at The Washington Post. A group of 67 researchers assembled a global carbon budget that estimates that carbon emissions for 2016 will be just 0.2 percent above 2015 levels, Mooney reports.

"It’s definitely three years, it’s fairly flat, which is quite a contrast to a decade ago, when it was growing at about 3 percent," Glen Peters, one of the study's authors and a scientist at the Center for International Climate and Environmental Research-Oslo, tells Mooney. "It’s really leveled out the last few years."

The researchers suspect that the leveling out comes from a reduction in the use of coal in China and the United States. According to a press release, China’s carbon emissions have dropped by 0.7 percent over the last year, after growing five percent per year in the previous decade. It could also be an indication that humans are reaching peak emissions and that emissions will slowly reduce from here on out.

“I’d certainly give it five or more years before I’d say it’s a peak,” Peters tells Mooney. “But certainly you would say, even leveling out, like we have over the last three years, is a big surprise. If you’d stood back three years ago, we wouldn’t have been expecting this. So it’s certainly good news.”

Though it is good news, taken at face value it masks some stark realities. The leveling off of emissions will not arrest climate change. Earlier this week the World Meteorological Organization issued a report showing that 2011 to 2015 was the hottest five-year period on record and that 2016 will likely be the hottest year ever. Concentrations of carbon in the atmosphere are also the highest ever recorded. In fact, the WMO says that the average global temperature has risen by 1 degree Celsius (1.8 degree Fahrenheit) already. The Paris Climate agreement, for instance, has a goal of keeping temperatures from exceeding 2 degrees Celsius or 3.6 Fahrenheit. But, as Mooney points out, to stop climate change emissions would have to drop to zero or even go negative to meet those goals. 

And reducing emissions is getting harder.

As the world heats up, natural carbon “sinks” become less efficient, explains Corinne Le Quéré, Director of the Tyndall Centre at the University of East Anglia who led the carbon budget study. “Part of the CO2 emissions are absorbed by the ocean and by trees. With temperatures soaring in 2015 and 2016, less CO2 was absorbed by trees because of the hot and dry conditions related to the El Niño event,” she says in the press release. “Atmospheric CO2 levels have exceeded 400 parts per million (ppm) and will continue to rise and cause the planet to warm until emissions are cut down to near zero.”

The second "good news" study recently released takes aim at these carbon sinks. That study, published in the journal Naturesuggests that the rise of carbon dioxide levels led to a global “greening” between 2002 and 2014 that helped offset carbon emissions by roughly 20 percent. The increasing levels of carbon dioxide acted as a booster for the planet’s plant life, Trevor Keenan, lead author of the study and researcher at Lawrence Berkeley National Laboratory, tells Matt McGrath at the BBC. “We have a huge amount of vegetation on the Earth and that was being fertilized by CO2 and taking in more CO2 as a result,” Keenan says.

But the researchers say that the effect is temporary and at some point the vegetation's respiration and eventual decay will outstrip that absorption—an event that will release even more carbon dioxide into the atmosphere, reports Damian Carrington at The Guardian.

Even though the Paris Climate agreement, which recently went into effect, has been called “unstoppable” by UN secretary-general Ban Ki-moon with or without the participation of the United States, Karl Ritter at the Associated Press points out that carbon emission reductions agreed to in the deal are still not enough to reach the goal of keeping the global temperature rise under 2 degrees Celsius. The Intergovernmental Panel for Climate Change released a statement in September that estimates Earth will reach that degree of warming by 2050, much faster than originally believed. And the organization also recognizes that the emission cuts pledged in the Paris agreement are woefully inadequate.

Robert Watson, former head of the IPCC, says in a release, "if governments are serious about trying to achieve even the 2 degree goal, they will have to double and re-double their efforts—now."

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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