Welcome To The Miocene: Last Time W. CO2 @ These Levels, The Seas Were 120+ Feet Higher
This past week, atmospheric carbon dioxide levels passed a new ominous milestone. Clocking in at 410.7 parts per million at the Mauna Loa Observatory, this key heat trapping gas hit a range not seen on Earth for many millions of years.
?w=600&h=360
(The world crossed the 410 part per million milestone in the daily measure this week. Image source: The Keeling Curve.)
These levels now correspond with the Miocene Climate Epoch when seas were 120 to 190 feet higher than today and when global temperatures ranged from 3 to 5 degrees Celsius hotter than preindustrial averages.
These new records come following two years of record rates of atmospheric CO2 accumulation. According to NOAA, carbon dioxide accumulated by 3.03 parts per million during 2015 and by 3.00 parts per million during 2016. These now represent the two fastest rates of carbon dioxide accumulation in the climate record to date. By comparison, the substantial warming at the end of the last ice age was accompanied by an approximate 0.01 part per million per year rate of CO2 increase averaged over 10,000 years.
2017 rates of atmospheric CO2 accumulation, according to NOAA, appear to have backed off somewhat in the first quarter. Comparative gains from Q1 2016 to Q1 2017 are about 2.8 parts per million. A weak La Nina in the Pacific during late 2016 probably helped ocean surfaces to cool and to draw down a bit more CO2. However, the rate of increase is still disturbingly rapid. A 2.8 ppm increase in 2017, should it emerge, would be the 4th highest annual rate of increase in the record and would be substantially above past decadal averages. Hopefully, this still-disturbingly-rapid rate of increase will continue to tail off a bit through the year. But it is increasingly clear that the time for urgent action to reduce carbon emissions and this very harmful related rate of accumulation is now upon us.
?w=600&h=448
(The CO2 growth rate has recently been ramping higher due to record carbon emissions during the present decade. Rates of carbon emission will need to fall away from record high rates in order to tamp down the presently high rate of accumulation which will tend to trend higher even if such emissions remain at plateau due to various faltering carbon sinks and leaking natural carbon stores. Image source: NOAA.)
EDIT
https://robertscribbler.com/2017/04/26/key-heat-trapping-gas-crosses-410-parts-per-million-threshold-highest-level-in-past-5-20-million-years/#comments
= new reply since forum marked as read
