Monday, October 30, 2017

Carbon dioxide: a record increase to a record level

The absolute levels of CO2 have been increasing since reliable records began 60-odd years ago. What is particularly alarming, though, is the rate of increase ion recent years. An average concentration of 403.3 parts per million was recorded in 2016, based on readings in 51 countries by the World Meteorological Organization. This represents an increase of 3.3 ppm in just one year, about 50% more than the average annual increase over the last ten years, for example.
The last time anything like an increase of this magnitude was recorded was back in 1998, when an increase of 2.7 ppm was recorded. Both years were intense El Niño years (El Niño tends to cause droughts that limit the uptake of CO2 by plants and trees). The 2016 increase was substantially higher than 1998, though, which points to a significant increase in the underlying man-made CO2 levels.
The last time CO2 levels were at or above these levels was around three to five million years ago, during the mid-Pliocene era, when average temperatures were 2-3°C higher, and sea levels were 10-20 metres higher due to the melting of the Greenland and West Antarctic ice sheets. That time we humans were not involved, but we really don't want to go there again.

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