Paleoenvironmental changes across the Mesozoic–Paleogene hyperthermal events

Abstract

Extreme climate warmth (hyperthermal) events through deep-time offer prescient insights into how the Earth may respond to present-day warming related to greenhouse gas emissions. This special issue deals with Paleoenvironmental changes across the Mesozoic–Paleogene hyperthermal events and comprises 25 interdisciplinary research articles. In this review paper, we summarise the contents of the special issue, placing it into a wider context, and demonstrate that Mesozoic–Paleogene hyperthermal events were among the most devastating and extreme climate modes in the geological record. Key findings are as follows: (1) Multi-proxy geochemical and sedimentological analyses reveal that widespread deoxygenation of oceans and megalakes was a common accompanying feature of most hyperthermals. (2) Evidence exists for complex linkages between volcanism, warm climate conditions, contemporary carbon cycles, aquatic biogeochemical cycles, wildfire activities, and climate-modulated hydrological and terrestrial weathering changes operating at seasonal, orbital and/or tectonic timescales. (3) Pronounced and rapid biological turnovers in the ocean during hyperthermals may have been linked to seawater acidification and shifts in nutrient availability, while promoting significant alterations in primary productivity, biological pump and ecosystem structures. Despite these advances, future interdisciplinary studies are needed to deliver a more comprehensive understanding of the nature and mechanism of complex environmental interactions within the Earth system, as well as the internal and external drivers that may have triggered hyperthermal events.