Under rising anthropogenic CO2, the future of the tropical climate states and the response of the biosphere, specifically the fate of the tropical rainforest (TRF), is uncertain. Therefore, deep-time climate proxy records and model simulations are being extensively utilized to understand the possible response of the TRF community during extreme climate states. However, comprehensive climate-TRF proxy data from the tropical/equatorial region for the paleo-global warming episodes, e.g., Late Paleocene – Early Eocene interval (∼56 to 51 Ma, encompassing transient hyperthermal events like Paleocene-Eocene Thermal Maximum [PETM], Eocene Thermal Maximum2 [ETM2]/H1/ Eocene Layer of Mysterious Origin [ELMO], H2, I1, and I2), are very limited and create difficulties in the validation of simulated results. Here we present long-term land surface temperature and precipitation (δ2H and δ18O of pedogenic clay mineral-derived) and TRF diversity (palynology) data from a paleo-equatorial region, spanning the ∼56 to 51 Ma interval. Present data suggest that the hydrological response to global warming was not temporally uniform in the paleo-equatorial land. While a significantly increased rainfall buffered the terrestrial temperature during the PETM, an insignificant increase in precipitation and negligible temperature lowering can be observed during the ETM2 hyperthermal event. However, the climate system's response during the other Early Eocene hyperthermals, i.e., H2, I1, and I2, was very similar to the PETM. Despite these small aberrations, the long-term average equatorial land surface temperature (27 ± 4 °C) during the Early Eocene greenhouse episode remained very similar to the modern equatorial temperature (28–30 °C). Rainfall proxy and plant diversity data suggest that the precipitation aided TRFs' resilience and proliferation, possibly through temperature buffering, during this paleo-greenhouse episode.

中文翻译：

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始新世早期温室事件期间的温度-降水对决和热带绿化


在人为二氧化碳不断上升的情况下，热带气候国家的未来和生物圈的反应，特别是热带雨林 （TRF） 的命运，是不确定的。因此，深时气候代理记录和模式模拟被广泛用于了解 TRF 群落在极端气候状态下的可能反应。然而，来自热带/赤道地区古全球变暖事件的综合气候-TRF 代理数据，例如，晚古新世 - 早始新世间隔（∼56 至 51 马，包括短暂的高温事件，如古新世-始新世热最大值 [PETM]、始新世热最大值 2 [ETM2]/H1/神秘起源始新世层 [ELMO]、H2、I1 和 I2），非常有限，并在模拟结果的验证中造成困难。在这里，我们展示了来自古赤道地区的长期地表温度和降水（基生粘土矿物衍生的 δ2H 和 δ18O）和 TRF 多样性（古生物学）数据，跨越 ∼56 至 51 马 区间。目前的数据表明，在古赤道地区，水文对全球变暖的响应在时间上并不统一。虽然在 PETM 期间降雨量显著增加缓冲了地面温度，但在 ETM2 高温事件期间可以观察到降水的显着增加和可以忽略不计的温度降低。然而，气候系统在其他早始新世高温期间的响应，即 H2、I1 和 I2，与 PETM 非常相似。尽管存在这些小的偏差，但早始新世温室事件期间的长期平均赤道地表温度 （27 ± 4 °C） 与现代赤道温度 （28-30 °C） 非常相似。 降雨代理和植物多样性数据表明，降水可能有助于 TRF 的恢复力和增殖，可能是通过温度缓冲，在这次古温室事件中。