Potential multiple steady-states in the long-term carbon cycle

TL;DR

This study models the long-term carbon cycle and suggests the existence of multiple stable climate states, indicating that human-induced CO2 increases could push the climate into a higher temperature equilibrium.

Contribution

It introduces a model that incorporates biotic and geochemical processes, revealing potential multiple steady-states in Earth's climate system.

Findings

Identification of a second stable climate steady-state between 20 and 50°C.

Potential link between past warm periods and upper temperature steady-states.

Implication that anthropogenic CO2 could lead to a new, higher temperature equilibrium.

Abstract

In our modeling of the long-term carbon cycle we find potential multiple steady-states in Phanerozoic climates. We include the effects of biotic enhancement of weathering on land, organic carbon burial, oxidation of reduced organic carbon in terrestrial sediments and the variation of biotic productivity with temperature, finding a second stable steady-state appearing between 20 and 50 oC. The very warm early Triassic climate as well as an oceanic anoxic event in the late Cretaceous may be the potential candidates for an upper temperature steady-state. Given our results, the anthropogenic driven rise of atmospheric carbon dioxide could potentially push the climate into tipping points to a modestly higher temperature steady-state, instead of relaxing back to pre-anthropogenic conditions.