According to the mantra spouted by the global warming activists, the earth’s temperature has soared to unprecedented levels and the rate at which this condition has been achieved is also unprecedented. All this is due, of course, to the evil West and our reliance on fossil fuels. The burning of these fuels has increased carbon dioxide levels in the atmosphere which is the reason we are all going to die in a greenhouse oven. I think not.
There is little doubt that carbon dioxide levels in the atmosphere today are higher today than during any other period in the last half million years or so. We live in an interglacial and thankfully so. Life during an ice age would suck and it is probable that the rise of human civilization is due, almost entirely, to the start of the present (Holocene) interglacial. It is very hard to farm under 3,000 feet of ice!
So what about past interglacials? What were they like? Is the present interglacial really extraordinary? Are we living in an interglacial of unprecedented warmth? The answer to these questions lies trapped in Antarctic ice. Without going into the details of temperature reconstructions from ice core data it is worth noting that during the last half million years the Earth has gone through five interglacials and the data confirms that the previous four were all significantly warmer than the present (1, 2). The “unprecedented” nature of the present interglacial is not the higher degree of heat but is instead, the lack thereof!
Most significantly, the previous interglacials were accompanied by atmospheric carbon dioxide levels at least 30 % lower than current levels!
1. Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M.., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pepin, L., Ritz, C., Saltzman, E. and Stievenard, M. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399: 429-436.
2. Sime, L.C., Wolff, E.W., Oliver, K.I.C. and Tindall, J.C. 2009. Evidence for warmer interglacials in East Antarctic ice cores. Nature 462: 342-345.