Long-term future Greenland ice loss determined by peak global warming

Matteo Willeit , Alexander Robinson , Christine Kaufhold , Andrey Ganopolski

The Greenland ice sheet (GrIS) is known to be very sensitive to climate change, and persistent global warming only slightly higher than today could be enough to completely melt it. However, the implications of a temporary crossing of this temperature threshold for future GrIS mass loss remain unknown. Here we present simulations of the next 10,000 years under different future anthropogenic emissions scenarios, performed using a fully coupled Earth system model. We find that long-term Greenland ice loss is determined by the peak global temperature increase, which generally occurs within the next few centuries. The GrIS contribution to sea-level rise after 10,000 years increases by ∼1.5 m for each degree of warming above a critical peak global warming threshold of ∼1.5°C, which is close to the GrIS equilibrium tipping point. This finding is robust for different equilibrium climate sensitivities and across different scenarios. We also find that accounting for changes in the Earth’s orbital parameters over the next 10,000 years substantially increases the sensitivity of the GrIS mass loss to anthropogenic warming. Our results demonstrate how 21st century climate policy will largely determine the fate of the GrIS for millennia to come.