Far, far away from 350 ppm …
The goal of limiting atmospheric carbon dioxide to 350 parts per million — considered the environmentally “safe” level, just moved a little farther away. Scientists tracking concentrations of the heat-trapping pollutant at a mountaintop lab in Hawaii said last week that CO2 concentrations jumped by the largest annual amount recorded since measurements began 56 years ago.
The reading comes from NOAA’s Mauna Loa Observatory, and researchers said the latest increase was the fourth year in a row that CO2 concentrations grew by more than 2 parts per million, according to a press release from NOAA.
“Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years,” said Pieter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network. “It’s explosive compared to natural processes.”
The most recent annual measurement showed that atmospheric carbon dioxide jumped by 3.05 parts per million during 2015. The thickening blanket of invisible gas generated mostly by burning fossil fuels has helped drive global surface temperatures to new records nearly every month during the past year.
The current level of CO2 is higher than it has been in millions of years. That matters for many reasons, for example because scientists working in Antarctica said their research shows that, in ancient eras, there were massive meltdowns of ice sheets at similar CO2 levels — and sea level was many feet higher than today.
Much of the CO2 ends up being absorbed by the oceans, where it is acidifying the water. By mid-century, that could spell big trouble for fish and shellfish. Terrestrial plant growth could also suffer as a result of CO2 increases, according to a recent study in Nature Climate Change.
The big annual jump came despite recent findings that CO2 emissions have leveled off and perhaps even declined in 2015. A doubling of atmospheric carbon dioxide from pre-industrial levels would likely lead to a global temperature increase of at least 3 degrees Celsius, making parts of the planet uninhabitable.
In February 2016, the average global atmospheric CO2 level stood at 402.59 ppm. Prior to 1800, atmospheric CO2 averaged about 280 ppm.The last time the Earth experienced such a sustained CO2 increase was between 17,000 and 11,000 years ago, when CO2 levels increased by 80 ppm. Today’s rate of increase is 200 times faster, said Tans.
The big jump in CO2 is partially due to the current El Niño weather pattern, as forests, plantlife and other terrestrial systems responded to changes in weather, precipitation and drought. The largest previous increase occurred in 1998, also a strong El Niño year. Continued high emissions from fossil fuel consumption are driving the underlying growth rate over the past several years.
To track CO2 concentrations at Mauna Loa and global CO2 concentrations visit NOAA’s Greenhouse Gas Reference Network.