Really Sciency

Visit my other blog 'Really Sciency' looking at Climate Science and its portrayal, misrepresentation and denial in the media.

Thursday, 10 March 2011

CO2 Triggered a Global Warming 40 Million Years Ago

Atmospheric CO2 Triggered a Global Warming Event 40 Million Years Ago

Microfossils found in the drill cores.

An interesting study suggests that CO2 has been a primary driver of Co2 in the past;

It is interesting to see that they determined a very similar climate sensitivity to Hansen, IPCC etc. The article concludes;
"The result, he says, will help climatologists get a better grip on the concept of climate sensitivity—the degree to which a global temperature increase is entirely dependent on an accompanying rise in CO2. The authors conclude that the climate sensitivity during the MECO led to a 2- to 5-degree C increase per doubling of atmospheric CO2.

The study does leave one big question outstanding: Where did all the MECO CO2 come from? This remains an area of speculation, Houben says, although scientists are fairly sure the source was not organic."
One possibility I can think of that isn’t mentioned is Methane hydrate, an ice like combination of methane and water that forms in deep ocean. These have been studied as possible energy reserves by oil companies. There is now evidence that the methane in these can be released by events like undersea avalanches. These may have been the source of the massive Carbon Input During the Latest Paleocene Thermal Maximum.

"However the CO2 got there, the takeaway from this study is simple: "In the past," Zachos says, "whenever atmospheric carbon dioxide levels rise, the climate warms.""


  1. How many more studies that tell us CO2 is a primary driver of climate change do we need ? I wonder if in your penultimate paragraph you are talking about a 'Canfield Ocean' . It's the nightmare scenario which may have happened in the past.

  2. That the scientists don't think the source was organic argues against clathrates.

    Because C13 is heavier than C12 (normal carbon) biological processes preferentially utilise C12 and fix a carbon profile with a reduced C13 fraction. This applies to the action of bacteria in sediments decomposing detritus to produce CH4. So clathrate CH4 is reduced in C13 fraction. The C12/C13 ratio is detectable in carboniferous rocks.

    Chris R

  3. Hi Chris - this was just my idea and I never consider isotopes of carbon. Methane hydrate is implicated in the warming at the end of the Palaeocene 55 million years ago. Itis not thought to have acted alone as volcanic activity on a large scale occurred as well.

    If you are right about the isotopes of carbon then the only source of non biological carbon I can think of is again volcanic activity. Not sure if there is much evidence to support that 40 millions years ago though.

  4. hengist, I'm pretty ignorant of the 'Cranfield Ocean' but that seems to be related to the Proterozoic which is well before this time.