Carbon Dioxide Levels On The Rise In US

Carbon dioxide in the atmosphere is predicted to rise by a near-record amount in 2019, the Met Office has warned. The ability of natural “sinks”, such as forests and grasslands, to absorb the climate-warming gas has been reduced this year due to changing weather patterns in the Pacific, it said.

This combined with rising emissions from human activity, including burning fossil fuels, has meant scientists expect to record one of the largest-ever increases in CO2 levels in 62 years of measurements.

Professor Richard Betts, from the Met Office Hadley Centre, said: “Since 1958, monitoring at the Mauna Loa observatory in Hawaii has registered around a 30% increase in the concentration of carbon dioxide in the atmosphere. This is caused by emissions from fossil fuels, deforestation and cement production, and the increase would have been even larger if it were not for natural carbon sinks which soak up some of the excess carbon dioxide.”

Professor Betts continue, “This year we expect these carbon sinks to be relatively weak, so the impact of record high human-caused emissions will be larger than last year.” Average concentrations of carbon dioxide are forecast to be 411 parts per million (ppm) in 2019, reaching a peak of 414 ppm in May before dropping back to 408 ppm in September and rising again at the end of the year.

This is compared to around 315 ppm when measurements began at Mauna Loa in 1958, and around 280 ppm before the Industrial Revolution based on ice core samples. Weather patterns linked to year-by-year swings in Pacific Ocean temperatures are known to affect the uptake of carbon by plants.

In years with a warmer tropical Pacific, many regions become warmer and drier which limits plants growing and absorbing carbon dioxide. The opposite occurs when the Pacific is cooler, as it was a year ago.

Prof Betts said: “Looking at the monthly figures, it’s as if you can see the planet ‘breathing’ as the levels of carbon dioxide fall and rise with seasonal cycle of plant growth and decay in the northern hemisphere. But each year’s carbon dioxide is higher than the last, and this will keep happening until humans stop adding carbon dioxide to the atmosphere.”

Dr Dann Mitchell, senior lecturer in atmospheric science at the University of Bristol, said: “The problem here is that once carbon dioxide is released into the atmosphere it stays there for a very long time, and a large proportion will remain for thousands of years. So while the Met Office is forecasting yet another increase in carbon dioxide for the near future, the repercussions will also be felt for tens of generations.”