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Clim. Past Discuss., 7, 2803-2833, 2011
www.clim-past-discuss.net/7/2803/2011/ doi:10.5194/cpd-7-2803-2011 © Author(s) 2011. This work is distributed under the Creative Commons Attribution 3.0 License. |
Vegetation-climate interactions in the warm mid-Cretaceous
1Department of Earth and Environmental Sciences, University of Michigan, USA
2National Center for Atmospheric Research, Boulder, Colorado, USA
Abstract. Vegetation-climate interactions are thought to have amplified polar warmth during past warm periods. Here, we explore the vegetation-climate interactions in the mid- Cretaceous using a fully coupled ocean-atmosphere general circulation model with a dynamic vegetation component. We run simulations with 1×, 10× and 16× preindustrial atmospheric CO2. Results show that forests expand from mid-latitudes to high latitudes as CO2 increases from 1× to 10× and 16×, mainly due to the CO2- induced warming. This expansion of mid-to-high latitude forests are largely supported by the distribution of mid-Cretaceous fossil woods and coal deposits. Globally, the presence of vegetation increases mean annual temperature and precipitation by 0.9 °C and 0.11mm day−1 relative to bare ground. High-latitude warming induced by the presence of vegetation (∼1.9 °C) is less than half of that reported in previous studies. The weaker warming here is mainly due to less pronounced albedo feedbacks, and to a less extent, reduced poleward heat transport via weakening of the meridional overturning circulation. Our results suggest that other mechanisms in addition to high atmospheric CO2 and high-latitude vegetation are required to maintain the polar warmth.
Citation: Zhou, J., Poulsen, C. J., Rosenbloom, N., Shields, C., and Briegleb, B.: Vegetation-climate interactions in the warm mid-Cretaceous, Clim. Past Discuss., 7, 2803-2833, doi:10.5194/cpd-7-2803-2011, 2011.