Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation

The covariation of carbon dioxide (CO 2 ) concentration and temperature in Antarctic ice-core records suggests a close link between CO 2 and climate during the Pleistocene ice ages. The role and relative importance of CO 2 in producing these climate changes remains unclear, however, in part because the ice-core deuterium record reflects local rather than global temperature. Here we construct a record of global surface temperature from 80 proxy records and show that temperature is correlated with and generally lags CO 2 during the last (that is, the most recent) deglaciation. Differences between the respective temperature changes of the Northern Hemisphere and Southern Hemisphere parallel variations in the strength of the Atlantic meridional overturning circulation recorded in marine sediments. These observations, together with transient global climate model simulations, support the conclusion that an antiphased hemispheric temperature response to ocean circulation changes superimposed on globally in-phase warming driven by increasing CO 2 concentrations is an explanation for much of the temperature change at the end of the most recent ice age. A reconstruction of global surface temperature is used to show that deglacial temperature is correlated with and generally lags carbon dioxide concentration, a result that contributes to the explanation of the temperature change that occurred at the end of the most recent ice age. Carbon dioxide is a force behind deglaciation It is known from Antarctic ice-core records that there is a relationship between atmospheric carbon dioxide levels and temperature during the Pleistocene ice ages. But the phasing between the two has been unclear, leading to controversy about whether greenhouse gases were primary drivers of the ice ages, a feedback from warming or even a consequence rather than a cause of past climate change. Shakun et al . have assembled a global 'stack' of proxy temperature records for the most recent deglaciation, and find that during this period, global warming was preceded by CO 2 increases. These observations, together with transient global climate model simulations, suggest that CO 2 was a primary driver of global warming during the most recent deglaciation.