Monday, January 21, 2008

Tipping Point: 500 ppm

CURRENTLY: 384 parts per million (ppm)
as of January 21, 2008, according to news article by Reuters reporter Alistair Doyle
*[An expert in the field says that the Reuters figures are off. He writes: "Here's the last NOAA data set: NOAA says 384 is the current number, not 394:] **[This expert also notes: "I think most people now believe the tippping point comes well before 500 ppm".]

WAS: 383 ppm
as of December 28, 2007 oped article by Bill McKibben in the Washington Post
WAS WAS: 275 ppm
many years ago, in a time gone by
[An expert in the field tells us that he thinks that "most people in the field now believe the tipping point comes well before 500 ppm".]

See Alex Steffen's analysis here:

set now at *430 ppm -- (*not as accurate as this website, but a very interesting "countup" clock, and way cool because it's animted, tracking stats as you read this post!)


See L. David Roper analysis here:
[The result of fossil fuels and population growth peaking is that the amount of carbon dioxide being put into the atmosphere will peak. I have done a calculation taking those four peaks into account and have concluded that the carbon dioxide concentration in the atmosphere will go from its present value of about 385 parts per million to a peak of about 450 parts per million at about year 2100 and then will decline to about the same value as now for several centuries. Climatologists estimate that atmospheric concentration over 400 ppm will cause many disasters for humans on the Earth.

So, carbon dioxide in the atmosphere will not increase indefinitely, which is good news. But there is no reason for celebration because already, at 385 ppm, disastrous things are happening. Also, on the way to 450 ppm it is difficult to predict with assurance what other disasters will occur, but we can be sure that some will. One possibility that may greatly increase global warming, that seems to be already under way, is the release of massive amounts of carbon that is frozen in the Arctic tundra.]