Articles | Volume 12, issue 1
Clim. Past, 12, 151–170, 2016
Clim. Past, 12, 151–170, 2016

Research article 29 Jan 2016

Research article | 29 Jan 2016

The effect of a dynamic soil scheme on the climate of the mid-Holocene and the Last Glacial Maximum

M. Stärz1,2,3, G. Lohmann1,4, and G. Knorr1 M. Stärz et al.
  • 1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 2Senckenberg Research Institute and Natural History Museum, Frankfurt am Main, Germany
  • 3Biodiversity and Climate Research Centre (LOEWE BiK-F), Frankfurt am Main, Germany
  • 4University of Bremen, Bremen, Germany

Abstract. In order to account for coupled climate–soil processes, we have developed a soil scheme which is asynchronously coupled to a comprehensive climate model with dynamic vegetation. This scheme considers vegetation as the primary control of changes in physical soil characteristics. We test the scheme for a warmer (mid-Holocene) and colder (Last Glacial Maximum) climate relative to the preindustrial climate. We find that the computed changes in physical soil characteristics lead to significant amplification of global climate anomalies, representing a positive feedback. The inclusion of the soil feedback yields an extra surface warming of 0.24 °C for the mid-Holocene and an additional global cooling of 1.07 °C for the Last Glacial Maximum. Transition zones such as desert–savannah and taiga–tundra exhibit a pronounced response in the model version with dynamic soil properties. Energy balance model analyses reveal that our soil scheme amplifies the temperature anomalies in the mid-to-high northern latitudes via changes in the planetary albedo and the effective longwave emissivity. As a result of the modified soil treatment and the positive feedback to climate, part of the underestimated mid-Holocene temperature response to orbital forcing can be reconciled in the model.

Short summary
In order to account for coupled climate-soil processes, we developed a soil scheme which is asynchronously coupled to an earth system model. We tested the scheme and found additional warming for a relatively warm climate (mid-Holocene), and extra cooling for a colder (Last Glacial Maximum) than preindustrial climate. These findings indicate a relatively strong positive soil feedback to climate, which may help to reduce model-data discrepancies for the climate of the geological past.