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

[Display omitted] •Reconstructed palaeo-equatorial hydrological cycle of ETM-2.•Mean annual rainfall decreased significantly near the equator.•Deciduous forests expanded due to decreased rainfall.•Survival of equatorial rainforests is difficult under increased atmospheric CO2. 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.