Sometime last night while many of us slept, humanity past a milestone.
The concentration of carbon dioxide exceeded 400 parts per million – the highest concentration of CO2 in millions of years. The last time CO2 was at this level was roughly 3 million years during the mid-Pliocene. At that point the plant was at least 3-3 degrees warmer and sea levels 25 meters higher.
Reports coming in:
- From the ABC – “Global greenhouse gases in the atmosphere have reached an ominous milestone that is unprecedented in human history. The world’s longest measure of carbon dioxide in the atmosphere has reached 400 parts per million (PPM) for the first time in three million years…”
- The Scripps Institution of Oceanography is reporting slightly under 400ppm, but NOAA reports 400ppm.
Who know’s were we will be by centuries end: at this point with a lack of concentrated global effort, 600ppm looks likely.
We’re well on the way to doubling the level of C02 since the mid-nineteenth century (roughly 280ppm back then).
Welcome to the Anthropocene.
I’ll post thoughts on this later.
Watching the Deniers 
At around 2mm / year, with no sign of significant acceleration, your 25m SLR disaster will take 12,500 years to manifest…
Eric ignores everything observed and projected for SLR,and comes up with the idiot’s guide to sea level….thanks,E. At around 3.2 to 3.4mm/year mean rise according to UCAR or the CSIRO,what would they know,they just do the spade work…with a detected acceleration. Wrong again Worrall is back with the provocative nonsense strategy,playing dumb again.. even 50cm rise will mess up your kids premiums,Eric.
Some places it’s not rising that much,others it rising much faster,such as NE USA.
Why would you expect SLR to increase in exactly the way you blithely forecast,when the history of rise to date shows no such rigidity? Why?
A million times faster
Data showing that the daily average CO2 over the Pacific Ocean was 400.03 ppm as of May 9 was posted online by the National Oceanic and Atmospheric Administration’s monitoring center in Mauna Loa, Hawaii.
A separate monitor at the Scripps Institution of Oceanography in San Diego, California initially reported its May 9 data showing that atmospheric carbon dioxide was at 399.73 ppm, but later revised that to show 400.08 ppm.
The difference came down to time zone, with NOAA using the universal time clock and Scripps reporting on Hawaii time. When Scripps adjusted its measurements to UTC time, it concurred with NOAA that 400 ppm threshold had been breached.
Michael Mann, director of the Earth System Science Center at Penn State, said the main concern is the speed with which the concentrations of CO2 are rising.
“There is no precedent in Earth’s history for such an abrupt increase in greenhouse gas concentrations,” Mann, who has authored two books on climate change, told AFP.
“While living things can adapt to slow changes that took place over tens of millions of years, there is no reason to believe that they — and we — can adapt to changes that are a million years faster than the natural background rates of change.”
Mann said the last time scientists are confident that CO2 was sustained at the current levels was more than 10 million years ago, during the middle of the Miocene Period.
Back then, global temperatures were hotter, ice was sparse and sea level was dozens of meters higher than it is today.
“It took nature hundreds of millions of years to change CO2 concentrations through natural processes such as natural carbon burial and volcanic outgassing,” Mann said.
“What we are doing is unburying it. But not over 100 million years. We’re unburying it and burning it over a timescale of 100 years, a million times faster.”
And right on cue, see Brigham-Grette et al. (2013) Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia
This seminal study of the continuous 3.6 million year record from the Lake El’gygytgyn cores shows where just ~400ppmv CO2 can eventually take the planetary climate once the NH ice has gone.
Cue ludicrous attempts at denial at WTFUWT where Anthony demonstrates his usual frightening lack of topic knowledge. Fair warning to Eric – don’t bring that tripe here.
(cont…)
Science Daily article on Brigham-Grette et al.