Scientists monitoring Earth’s atmosphere using data from the Mauna Loa Observatory in Hawaii delivers the much-feared news: the atmosphere now contains 400 parts per million (ppm) of carbon dioxide (CO2), passing a symbolic threshold.
And there’s likely no turning back now, they added, with the Mauna Loa record “never again” showing CO2 concentrations below that symbolic level within our lifetimes.
While the burning of fossil fuels and other man-made contributors are exacerbating greenhouse gas presence in the atmosphere, scientists pointed to the El Niño phenomenon as a crucial factor in the sharp CO2 rise this year.
Lead study author and University of Exeter professor Richard Betts said that atmospheric CO2 levels do rise year-on-year owing to human emissions, but sea-surface temperature changes in the Pacific Ocean due to El Niño are causing an extra boost.
“This warms and dries tropical ecosystems, reducing their uptake of carbon, and exacerbating forest fires,” he explained, adding that the human emissions that are 25 percent higher than in the 1997 to 1998 El Niño all led to a record CO2 increase this year.
In 1958, the rising CO2 trend was detected by scientist Charles David Keeling when he started to record it at Mauna Loa, with early measurements at about 315 ppm. Sixty years later, this demonstrated an increase of 2.1 ppm on average.
Through a seasonal climate forecast model as well as statistical links with sea temperatures, Betts’ team predicted the average concentration this year to be 404.45 + -0.53 ppm, dipping to 401.48 + -0.53 in September before they resume their current rise in 2017. Last month, the researchers forecasted the maximum concentration of 407 ppm this year.
Even without the El Niño pushing the values up, the team is skeptical that CO2 levels will stay below 400 ppm again for at least one human lifetime.
This 400 ppm level, however, is not deemed unprecedented in the planet’s history, as Earth’s atmosphere was believed to be stable at 360 to 400 ppm during the mid-Pliocene period some 3 million years ago. During that time, water levels were up to 80 feet higher than at present.
But will this grim scenario mark any substantial change in the climate change we are now experiencing? Hardly, but it’s an important opportunity to gauge the situation.
“I do think that these numbers are important for awareness, really.… It's a reminder of the long-term effects we're having on the system,” Betts told Washington Post despite nothing “special” likely happening as we breach the 400 ppm mark.
The findings were detailed in the journal Nature Climate Change.
Photo: Simon Matzinger | Flickr
