Tropical snowline depression at the Last Glacial Maximum: Comparison with proxy records using a single-cell tropical climate model

摘要: [1] The substantial lowering of tropical snowlines at the Last Glacial Maximum (LGM), circa 21 kya, is examined using a modified version single-cell climate model Betts and Ridgway [1989]. These authors concluded that it was difficult to reconcile large depression LGM with small reduction in mean sea-surface temperature (SST) Climate: Long-Range Investigation, Mapping, Prediction (CLIMAP) reconstruction. Here, climatic implications snowline are compared, not CLIMAP, but proxies (δ18O Sr/Ca ratios corals, noble gas concentrations aquifers, alkenone Mg/Ca deep-sea sediments recent faunal reconstructions) whose values have been interpreted as implying lower surface temperatures tropics. It proves difficult, framework this model, coldest indicated paleotemperatures observed depression, which by itself found be consistent an SST ∼3 K. A cooling magnitude corresponds most closely warm-pool estimates based on paleothermometry. Discordance among various proxy reconstructions may result, least part, from regional variations change LGM.