Researchers say CO2 levels in the atmosphere will not fall below last year's average for quite a while.
For the first time ever last year, carbon dioxide (CO2) levels in the Earth’s atmosphere averaged above the 400 parts per million mark, and scientists are forecasting they will never fall below that mark for at least the remainders of our lifetimes, according to an article in the Washington Post.
CO2 levels have been rising all throughout the industrial era, from a level of about 280 ppm. Measurements taken at the Mauna Loa Observatory in Hawaii since the 1950s have recorded a steady climb due to humans putting more CO2 into the air than vegetation across the globe can pull out. The levels drop during the summer months when plants are growing, and rise again as the vegetation withers in the winter months.
The most current measurement, taken on June 12, recorded a level of 407.26 PPM, according to the National Oceanic and Atmospheric Administration’s (NOAA) Earth System Research Laboratory, and current models predict the levels have a slight possibility of dropping below the 400 PPM mark, but scientists think it is unlikely.
The researchers, led by Richard Betts of the U.K. Met Office’s Hadley Center, said in a paper published in Nature Climate Change, “Our forecast supports the suggestion that the Mauna Loa record will never again show CO2 concentrations below the symbolic 400 ppm within our lifetimes.”
The team predicts an increase in the average of about 3.15 ppm for the year, which will exceed the greatest single year increase of 2.9 ppm recorded in 1997-1998, caused by an El Niño event. The same type event which we are experiencing in the 2015-2016 season, is driving the increase for this year as well, according to the researchers.
Because CO2 is a very long-lived greenhouse gas, it will continue to record high levels in the atmosphere each year, and even if we can find a way to reduce emissions, the levels will not likely drop back below 400 ppm for quite some time.
The research team says there is no magical event associated with the passing of the 400 ppm mark, and they don’t expect to see any catastrophic results, but they say the threshold is a reminder of the long-term effects we are having on the planet.
If left unchecked, carbon emissions will eventually lead to massive ice melts and rising sea levels, threatening coastal communities around the world.