The last interglacial climate:comparing direct and indirect impacts of insolation changes

• Published in: Climate Dynamics
• Main Authors: Pedersen, Rasmus A., Langen, Peter L., Vinther, Bo M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: AMOC; EC-Earth; Eemian; General circulation model; Last interglacial; Monsoon; Arctic; Global warming; North Atlantic; Sea ice
• Online Access: https://researchprofiles.ku.dk/da/publications/79e51f49-21f3-4ee4-8cca-f5baefec0336; https://doi.org/10.1007/s00382-016-3274-5; https://curis.ku.dk/ws/files/189733333/art_10.1007_s00382_016_3274_5.pdf

The last interglacial climate was influenced by substantial changes in the annual insolation cycle that led to a warmer climate state with pronounced high northern latitude warming. We analyze the impact of the insolation changes 125,000 years before present using an equilibrium snapshot simulation with the EC-Earth coupled climate model at high spatial resolution. Using additional atmosphere-only simulations, we separate the direct impact from the changed insolation from the secondary contribution from changed sea surface conditions. These simulations are forced with a combination of last interglacial sea surface temperatures and sea ice conditions and pre-industrial insolation, and vice versa. The coupled simulation yields an annual mean global warming of approximately 0.5 °C compared to pre-industrial conditions. While the warming over the continents follows the annual cycle of the insolation anomalies, two regions exhibit persistent responses throughout the year: The tropical region exhibits lower temperatures and stronger monsoonal systems, while the Arctic region shows a warming of more than 2 °C in all seasons. The hybrid simulations reveal that the changed sea surface conditions dominate the response at high northern latitudes, including the North Atlantic region and Europe, while the direct insolation impact is more dominant in the tropics.