A 30,000-year paleotemperature record derived from noble gases dissolved in carbon-14-dated ground water indicates that the climate in lowland Brazil (Piaui Province, 7°S, 41.5°W; altitude, 400 meters) was 5.4° ± 0.6°C cooler during the last glacial maximum than today. This result suggests a rather uniform cooling of the Americas between 40°S and 40°N. A 5.4°C cooling of tropical South America is consistent with pollen records, snow line reconstructions, and strontium/calcium ratios and δ18O coral records but is inconsistent with the sea-surface temperature reconstruction of CLIMAP (Climate: Long-Range Investigation, Mapping and Prediction). On the basis of these results, it appears that the tropical Americas are characterized by a temperature sensitivity comparable to that found in higher latitudes.
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