Union Climate of the Past Quantifying the effect of vegetation dynamics on the climate of the Last Glacial Maximum

The importance of the biogeophysical atmosphere-vegetation feedback in comparison with the radiative effect of lower atmospheric CO 2 concentrations and the presence of ice sheets at the last glacial maximum (LGM) is investigated with the climate system model CLIMBER-2. Equilibrium experiments reveal that most of the global cooling at the LGM ( −5.1C) relative to (natural) present-day conditions is caused by the introduction of ice sheets into the model ( −3.0C), followed by the effect of lower atmospheric CO 2 levels at the LGM ( −1.5C), while a synergy between these two factors appears to be very small on global average. The biogeophysical effects of changes in vegetation cover are found to cool the global LGM climate by 0.6C. The latter are most pronounced in the northern high latitudes, where the taiga-tundra feedback causes annually averaged temperature changes of up to −2.0C, while the radiative effect of lower atmospheric CO 2 in this region only produces a cooling of 1.5 C. Hence, in this region, the temperature changes caused by vegetation dynamics at the LGM exceed the cooling due to lower atmospheric CO2 concentrations.

[1]  Sandy P. Harrison,et al.  Climate change and Arctic ecosystems: 1. Vegetation changes north of 55°N between the last glacial maximum, mid‐Holocene, and present , 2003 .

[2]  A. Ganopolski.  Glacial integrative modelling , 2003, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[3]  Sandy P. Harrison,et al.  Climate and CO2 controls on global vegetation distribution at the last glacial maximum: analysis based on palaeovegetation data, biome modelling and palaeoclimate simulations , 2003 .

[4]  Seong-Joong Kim,et al.  A coupled climate model simulation of the Last Glacial Maximum, Part 2: approach to equilibrium , 2003 .

[5]  V. Brovkin,et al.  Stability Analysis of the Climate-Vegetation System in the Northern High Latitudes , 2003 .

[6]  R. Stouffer,et al.  The effect of ocean dynamics in a coupled GCM simulation of the Last Glacial Maximum , 2003 .

[7]  Victor Brovkin,et al.  Carbon cycle, vegetation, and climate dynamics in the Holocene: Experiments with the CLIMBER‐2 model , 2002 .

[8]  V. Brovkin,et al.  Ocean biology could control atmospheric δ13C during glacial‐interglacial cycle , 2002 .

[9]  B. McAvaney,et al.  Influence of vegetation changes during the Last Glacial Maximum using the BMRC atmospheric general circulation model , 2001 .

[10]  Stefan Rahmstorf,et al.  Rapid changes of glacial climate simulated in a coupled climate model , 2001, Nature.

[11]  Victor Brovkin,et al.  CLIMBER-2: a climate system model of intermediate complexity. Part I: model description and performance for present climate , 2000 .

[12]  Victor Brovkin,et al.  CLIMBER-2: a climate system model of intermediate complexity. Part II: model sensitivity , 2001 .

[13]  J. Jouzel,et al.  Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica , 1999, Nature.

[14]  Stefan Rahmstorf,et al.  Simulation of modern and glacial climates with a coupled global model of intermediate complexity , 1998, Nature.

[15]  S. Baum,et al.  Effect of vegetation on an ice-age climate model simulation , 1997 .

[16]  Pinhas Alpert,et al.  Factor Separation in Numerical Simulations. , 1993 .