Coupled atmosphere-oceanvegetation simulations for modern and mid-Holocene climates: role of extratropical vegetation cover feedbacks. Climate Dynamics 25: 755–776

• Main Authors: Robert Gallimore, Robert Jacob, John Kutzbach
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Tundra
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.476.7248; http://ccr.meteor.wisc.edu/resources/publications/pdfs/CCR_867.pdf

Abstract A full global atmosphere-ocean-land vegetation model is used to examine the coupled climate/vegetation changes in the extratropics between modern and mid-Holocene (6000 yr BP) times and to assess the feedback of vegetation cover changes on the climate response. The model produces a relatively realistic natural vegetation cover and a climate sensitivity comparable to that realized in previous studies. The simulated mid-Holocene climate led to an expansion of boreal forest cover into polar tundra areas (due mainly to increased summer/fall warmth) and an expansion of middle latitude grass cover (due to a combination of enhanced temperature seasonality with cold winters and interior drying of the continents). The simulated poleward expansion of boreal forest and middle latitude expansion of grass cover are consistent with previous modeling studies. The feedback effect of expanding boreal forest in polar latitudes induced a significant spring warming and reduced snow cover that partially countered the response produced by the orbitally-induced changes in radiative forcing. The expansion of grass cover in middle latitudes worked to reinforce the orbital forcing by contributing a spring cooling, enhanced snow cover, and a delayed soil water input by snow melt. Locally, summer rains tended to increase (decrease) in areas with greatest tree cover increases (decreases); however, for the broad-scale polar and middle latitude domains the climate responses produced by the changes in vegetation are relatively much smaller in summer/fall than is found in previous studies. This study highlights the need to develop a more comprehensive strategy for investigating vegetation feedbacks. 3