A transient shift in equatorial hydrology and vegetation during the Eocene Thermal Maximum 2

Abstract

The equatorial evergreen forests nourish the world's biodiversity hotspots and are considered the lungs of the Earth. However, their future survival is uncertain, due to anthropogenically increased carbon emissions and changes in the hydrological cycle. Understanding the changes in the hydrological cycle in the equatorial region due to an increase in carbon emission is of prime importance. The early Paleogene hyperthermal events are potential analogs to understand the consequences of high carbon emission on the hydrological cycle. In this communication, we quantify the terrestrial seasonal climate using the plant proxy and infer that during the Eocene Thermal Maximum 2 when atmospheric carbon dioxide concentration was > 1000 ppmv near the palaeo-equator (∼0.6°N), the rainfall decreased significantly, leading to the expansion of deciduous forests. This study raises important questions about the future survival of equatorial rainforests and biodiversity hotspots under increased carbon emissions.

Keywords

Coexistence approach / Climate / ETM-2 / Global warming / Hyperthermal / Paleogene

CRediT authorship contribution statement

Luyi Yang: Formal analysis, Methodology, Writing – original draft. Xuan Ji: Conceptualization, Funding acquisition, Writing – review & editing. Meng Li: Data curation. Pengwu Yang: Data curation. Wei Jiang: Writing – review & editing. Linyan Chen: Writing – review & editing. Chuanjian Yang: Writing – review & editing. Cezong Sun: Writing – review & editing. Yungang Li: Conceptualization, Writing – review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Key Research and Development Program of China (Grant No. 2022YFF1302405), the Yunnan Province Key Research and Development Program (Grant No. 202203AC100005), the National Natural Science Foundation of China (Grant No. 42061005, 42067033), and Applied Basic Research Programs of Yunnan Province (Grant No. 202101AT070110, 202001BB050073).

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