The only measurement that matters is greenhouse-gas emissions—and they continued to rise.
We’ve lost another decade on climate change.
Even as greenhouse gases in the atmosphere race toward levels that could lock in catastrophic warming, the world continued to pump out more. Our collective failure to begin cutting emissions over the last 10 years almost certainly shatters the dream of halting rising temperatures at 1.5 ˚C. Indeed, it’s hard to imagine achieving the pace and scale of change now required even to prevent 2 ˚C.
Among other sharply escalating dangers, that half-degree difference could doom the world’s coral reefs and regularly expose nearly 40% of world’s population to staggering heat waves.
There were faint signs of progress. Renewables and electric vehicles finally took off, and nearly 200 countries committed to cutting their emissions under the landmark Paris climate agreement in 2016.
(See our related story on the slow progress of clean energy development during the last decade here.)
But nations are already falling behind on their pledges, and the US is in the process of pulling out of the deal entirely, at a point when much deeper cuts are required. And for all the momentum behind clean energy technologies, they’ve done very little so far to displace the power plants, cars, factories, and buildings polluting the atmosphere with more emissions each year.
The charts that follow reveal how much ground we lost on climate change during the last 10 years.
Rising CO2 concentrations
The measurement that ultimately matters on climate change is global emissions. And they continued to rise.
There was a brief hope that greenhouse-gas pollution had finally plateaued. Carbon dioxide from fossil fuels, which makes up about 90% of total emissions from human activities, was relatively flat from 2013 through 2016.
Improving energy efficiency, rising use of renewables, and the shift from coal to natural gas likely drove much of this, particularly in wealthy economies like the US and European Union. But emissions have surged in the years since, driven largely by economic growth and increasing energy demands in emerging nations, led by China and India.
Fossil-fuel emissions rose an estimated 0.6% to a record 37 billion metric tons in 2019, capping three straight years of growth, the Global Carbon Project reported in early December.
These trends, plus additional emissions from land-use changes and other human activities, added up to steadily rising carbon dioxide concentrations in the atmosphere throughout the 2010s.
Reaching the peak
When we reach peak emissions matters. The longer we take, the deeper we’ll need to cut carbon pollution in the coming years if we hope to avoid dangerous warming thresholds, as the charts below show.
To get a sense of how much harder we’ve made the job of halting warming at 1.5 ˚C by frittering away the last decade, click on the chart and compare the steepness of the slope shown if we had plateaued in 2010 with what is projected should we reach the peak in 2020.
(These charts were produced by Zeke Hausfather for Carbon Brief, using data and the original figure from Robbie Andrew at the Center for International Climate Research.)
We’ll have to radically accelerate emissions reductions to have any hope of limiting warming to 2 ˚C as well.
In addition to aggressive emissions cuts, most models now find we’ll also need to use trees, plants and other methods to remove and store vast amounts of carbon dioxide from the atmosphere to stay below these temperature targets. But achieving these so called “negative emissions” on a large-enough scale will be incredibly costly, and compete directly with other crucial land-uses, most notably the farming needed to feed a growing global population.
Environmental impacts
Decades of rising emissions continued to do what scientists have long warned they would: make the world hotter.
In early December, the World Meteorological Organization announced that 2019 is likely to be the second or third warmest on record, capping a “decade of exceptional global heat.” Average temperatures for the preceding five- and 10-year periods will almost certainly be the highest on record.
This chart, using data from the National Oceanic and Atmospheric Administration, clearly highlights the rise in global land temperatures above the 20th-century average. Note the particularly pronounced increase in the last 10 years.
Ocean temperatures rose as well, and warmer water expands. That plus the accelerating loss of ice sheets and glaciers pushed up ocean levels further, as this chart from NASA satellite data highlights.
Indeed, the 2010s mark the decade when the impacts from climate change became unmistakable, at least for any objective-minded observer. As temperatures rose, Arctic sea ice melted far faster than models had predicted. The world’s coral reefs suffered widespread and devastating bleaching events. And regions around the world grappled with some of the costliest, deadliest, and most extreme droughts, hurricanes, heat waves, and wildfires in recorded history.
Since carbon dioxide takes years to reach its full warming effect, and we have yet to even begin cutting emissions, we’ll face even starker dangers in the coming decade.
