- Atmospheric carbon dioxide rose at record rate in 2015 and 2016
- Still rising in 2017 despite lack of El Nino and a leveling off of carbon emissions from human activities
- Are natural sinks weakening?
CAPE GRIM, Tasmania — …For more than two years, the monitoring station here, along with its counterparts across the world, has been flashing a warning: The excess carbon dioxide scorching the planet rose at the highest rate on record in 2015 and 2016. A slightly slower but still unusual rate of increase has continued into 2017.
Scientists are concerned about the cause of the rapid rises because, in one of the most hopeful signs since the global climate crisis became widely understood in the 1980s, the amount of carbon dioxide that people are pumping into the air seems to have stabilized in recent years, at least judging from the data that countries compile on their own emissions.
That raises a conundrum: If the amount of the gas that people are putting out has stopped rising, how can the amount that stays in the air be going up faster than ever? Does it mean the natural sponges that have been absorbing carbon dioxide are now changing?
…Scientists have spent decades measuring what was happening to all of the carbon dioxide that was produced when people burned coal, oil and natural gas. They established that less than half of the gas was remaining in the atmosphere and warming the planet. The rest was being absorbed by the ocean and the land surface, in roughly equal amounts.
In essence, these natural sponges were doing humanity a huge service by disposing of much of its gaseous waste. But as emissions have risen higher and higher, it has been unclear how much longer the natural sponges will be able to keep up.
Should they weaken, the result would be something akin to garbage workers going on strike, but on a grand scale: The amount of carbon dioxide in the atmosphere would rise faster, speeding global warming even beyond its present rate. It is already fast enough to destabilize the weather, cause the seas to rise and threaten the polar ice sheets.
The record increases of airborne carbon dioxide in 2015 and 2016 thus raise the question of whether this has now come to pass. Scientists are worried, but they are not ready to draw that conclusion, saying more time is needed to get a clear picture.
Many of them suspect an El Niño climate pattern that spanned those two years, one of the strongest on record, may have caused the faster-than-usual rise in carbon dioxide, by drying out large parts of the tropics. The drying contributed to huge fires in Indonesia in late 2015 that sent a pulse of carbon dioxide into the atmosphere. Past El Niños have also produced rapid increases in the gas, though not as large as the recent ones.
Yet scientists are not entirely certain that the El Niño was the main culprit; the idea cannot explain why a high rate of increase in carbon dioxide has continued into 2017, even though the El Niño ended early last year….
….Human activity is estimated to be pumping almost 40 billion tons of carbon dioxide into the air every year, an amount that Dr. Canadell of the Global Carbon Project called “staggering.” The atmospheric concentration of the gas has risen by about 43 percent since the Industrial Revolution. That, in turn, has warmed the Earth by around 2 degrees Fahrenheit, a large number for the surface of an entire planet.