We’ve had the hottest year on record, the warmest Arctic winter in human history, and it now appears that the level of carbon dioxide in the atmosphere grew more in 2015 than at any other point over the last 56 years. The dramatic spike is thought to be down to the continual pumping of CO2 into the atmosphere by humans, but has also been exacerbated by the historically strong El Niño that has battered the western coast of the Americas over the last 12 months.
For the past decade, the average increase in the concentration of carbon dioxide in the atmosphere has been by around 2 parts per million (ppm) a year, but 2015 saw this double as records show that the levels of CO2 increased by 3.05 ppm, while in the year leading up to February 2016 it climbed even higher, increasing by 3.76 ppm. According to the National Oceanic and Atmospheric Administration (NOAA), this is the fourth consecutive year in which the concentration of atmospheric carbon dioxide has increased by more than 2 ppm.
While CO2 levels go up and down during the year, there is still a clear upward trend. NOAA
It is true that the level of carbon dioxide in the atmosphere fluctuates over the period of a year, as plants and trees take in more CO2 during spring when they’re growing and release it again as they drop their leaves in autumn, but the overall trend has overwhelmingly been one in which CO2 levels have dramatically ramped up. At the beginning of the industrial revolution, the carbon dioxide levels in the atmosphere came in at around 280 ppm; now they’re sitting at 403 ppm.
While the records from the Mauna Loa Observatory in Hawaii, the world’s oldest continuous atmospheric measurement station, only go back around 56 years, researchers are able to look further into our planet's atmospheric past. By analyzing ice cores taken from Greenland and Antarctica, both of which contain ice that dates up to 800,000 years old, scientists are able to find trapped air bubbles from which they can measure directly the concentration of carbon dioxide in the atmosphere when the ice formed.
We have accurate records for atmospheric CO2 dating back hundreds of thousands of years. Robert A. Rohde/Wikimedia Commons
The cores show how while there were fluctuations in CO2 over the last millennium, these were stable until the early 19th century, with concentrations now 40 percent higher than they were before the industrial revolution. Using this data, scientists have been able to see that the fastest natural increase in CO2 levels over the past 800,000 years was around 12,000 years ago when it went up by 20ppm over the course of a thousand years. Carbon dioxide levels have increased by this same amount – 20ppm – in just the last ten years alone.
“Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years,” explains Pieter Tans, a lead scientists at NOAA. “It’s explosive compared to natural processes.” The researchers are hoping that this new data might add pressure to governments to sign into law the commitments made in Paris last year, and to finally get down to tackling climate change.