By: Greg Laden

Greg Laden — Fri, 14 Dec 2007 14:12:49 +0000

AA:Note that the Vostok core data you link to shows the maximum CO2 in parts per million (volume) at less than about 295-300 for all of the time represented. The current level is cloeser to 380 or higher. We have not seen CO2 concentrations as low as those shown in this core data in somewhere between 50 and 100 years in the past (you could check this, but I’m pretty sure that is close).It is not the case that temperature correlates perfectly with CO2, so I can’t say that the world has not really been warmer (since the beginning of the Cenozoic) but it may be accurate to say that the amount of free carbon floating around has not bee higher for a very long time.

By: AtheistAcolyte

AtheistAcolyte — Fri, 14 Dec 2007 13:24:24 +0000

Interesting. Many people say that “the world has been warmer before”, and point to the Milankovitch cycle graphs from ice cores in the distant past ( > 3,000 years ago), but forget completely that the rate at which the planet is apparently warming is the highest it’s ever been in natural phenomena.For an image like this: (full resolution)http://upload.wikimedia.org/wikipedia/commons/7/77/Vostok_420ky_4curves_insolation.jpgThe current rate of warming (0.178 degree K/decade) translates to a perfectly vertical for 5.75 degrees (a pixel represents about 325 years, and the major temperature shift at ~325 kya represents an 11-degree change over approximately 11,000 years. (~.01 degree Kelvin per decade)Our current rate of warming is some 17 times faster than recognized natural rates from ice cores. I’d say that’s statistically significant.

Comments on: 2007 was a very, very warm year

By: Greg Laden

By: AtheistAcolyte