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

Rasmus A Pedersen,Bo M Vinther,Peter L Langen

doi:10.1007/s00382-016-3274-5

Rasmus A Pedersen, Bo M Vinther + Show 1 more

Open Access

https://doi.org/10.1007/s00382-016-3274-5

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Abstract

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.

Highlights

The last interglacial (LIG; known as the Eemian or MIS5e) lasted from 129 to 116 thousand years before present
The EC-Earth coupled general circulation models (GCMs) simulation of the last interglacial climate exhibits an annual mean near-surface warming of 0.5 K compared to pre-industrial conditions
In agreement with previous studies, the temperature change over the continents follow the annual cycle of the insolation changes, but we find important regional exceptions: (1) the monsoonal regions in Africa and India exhibit cooling throughout the year, and (2) Greenland, Europe, and the Northern part of Asia exhibit warming throughout the year

Summary

Introduction

The last interglacial (LIG; known as the Eemian or MIS5e) lasted from 129 to 116 thousand years before present (ka). Changes in the orbital configuration and the insolation resulted in global warming of up to 2 °C compared to pre-industrial conditions, with more pronounced warming at high latitudes (CAPE-Last Interglacial Project Members 2006; Masson-Delmotte et al 2013; Capron et al 2014). Future greenhouse gas warming is expected to result in polar amplification of the surface temperature response (Serreze and Barry 2011), which could resemble the pronounced high-latitude temperature response during LIG The availability of paleoclimate information means that climate model simulations of the last interglacial are an opportunity to evaluate model performance outside of near-present day conditions, potentially leading to improved projections of future warming (OttoBliesner et al 2006; Braconnot et al 2012; Otto-Bliesner et al 2013)

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