also confound analysis: the latter two are each estimated to reduce estimated temperatures by 1−2 °C, and are difficult to quantify. Reconciling the data with the model Taking the data to be true, how could they be reconciled with the predictions of the model? The only way the model could be "tweaked" was by fiddling with the parameterisation of clouds, one of the most unpredictable aspects of any model. The model was adjusted to assume that the higher levels produced more tropical cloud-cover, shielding these regions from the sun's heat. However, there was no evidence for this behaviour, and still left problems. The poles were still warmer than the models predicted. Further feedbacks, including increased poleward heat transport by the oceans, and vegetational responses at high latitudes, were proposed, but these didn't fully explain behaviour in the southern hemisphere, and winter, respectively. Unravelling the paradox Hints of warmth - terrestrial proxies Data from terrestrial proxies suggested that the equator may have reached 30 °C - however, this figure is based upon extrapolation of data found outside the tropics. This would imply that the foramaniferal proxies were wrong - the tests may perhaps have been overprinted by diagenesis. Researchers turned to shallow marine molluscs as it is easy to determine whether their shells had been altered by diagenesis. Detecting diagenesis in molluscs Many mollusc shells are constructed from aragonite, a mineral that is quickly replaced by calcite by diagenetic alteration. Also, near-shore molluscs preserve seasonal variability in their shells, a feature that would be lost in the presence of a diagenetic signal. This removes ambiguity about whether or not a shell has been affected by post-deposition processes. Data from molluscs Evidence from the molluscs suggested a cooling between the Eocene and Oligocene. Taken from the Mississippi embayment, they recorded temperatures of around 26 °C in the Eocene, and 22 °C in the Oligocene; this cooling was markedly seasonal, with reconstructed water temperatures being 5° cooler in the summer, but just 3° cooler in winter. This trend fits best if was the dominant force for cooling. The winter temperatures of molluscs match well with the foramaniferal temperatures, suggesting that foramanifera predominantly grew during the winter months. The overall temperatures corresponded well with terrestrial and modelled estimates of a sea surface temperature around 4–5° warmer than today's. Reassessment of the foraminiferal record The magnesium/calcium paleothermometer is a recently developed alternative to the δ18O