The EPICA challenge to the Earth system modeling community

One of our major aims as Earth systems scientists is to predict how the Earth will behave in the future, particularly in the face of changes imposed upon it as a result of human activities. These predictions are made using models and concepts that are in part derived from observation of how the system has behaved in the past. However, these observations, which come from paleo-records, are also one important tool for validating the models. The imminent appearance of a new ice core data set presents a unique opportunity for a test of our understanding, particularly of the climate/carbon system. Members of the European Project for Ice Coring in Antarctica (EPICA) and others here present a challenge to the modeling communities and other interested parties. The Vostok ice core record has become an iconic data set. It presents the climate of the last 420 kyr, showing the rise and fall of Antarctic temperature through four complete glacial/interglacial cycles. The most striking finding is that CO2 and CH4, the two most significant greenhouse gases (after water vapor), also rise and fall, in a remarkably similar fashion. When Antarctic temperature is calculated including a correction for the climate of the water vapor source region, the correlation between CO2 and Antarctic temperature over the last 150 kyr has an r2 of 0.89!

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