Why does the Antarctic Peninsula Warm in climate simulations?
- 196 Downloads
The Antarctic Peninsula has warmed significantly since the 1950s. This pronounced and isolated warming trend is collectively captured by 29 twentieth-century climate hindcasts participating in the version 3 Coupled Model Intercomparison Project. To understand the factors driving warming trends in the hindcasts, we examine trends in Peninsula region’s atmospheric heat budget in every simulation. We find that atmospheric latent heat release increases in nearly all hindcasts. These increases are generally anthropogenic in origin, and account for about 60% of the ensemble-mean warming trend in the Peninsula. They are driven primarily by well-understood features of the anthropogenic intensification of global hydrological cycle. As sea surface temperature increases, moisture contained in atmospheric flows increases. When such flows are forced to ascend the Peninsula’s topography, enhanced local latent heat release results. The mechanism driving the warming of the Antarctic Peninsula is therefore clear in the models. Evidence for a similar mechanism operating in the real world is seen in the increasing snow accumulation rates inferred from ice cores drilled in the Peninsula. However, the relative importance of this mechanism and other processes previously identified as potentially causing the observed warming, such as the recent sea ice retreat in the Bellingshausen Sea, is difficult to assess. Thus the relevance of the simulated warming mechanism to the observed warming is unclear, in spite of its robustness in the models.
KeywordsAntarctic Peninsula Warming Latent heat transport
This work was supported by NSF-0735056. We acknowledge the modeling groups, the Program for Climate Model Diagnosis and Intercomparison (PCMDI) and the WCRP’s Working Group on Coupled Modelling (WGCM) for their roles in making available the WCRP CMIP3 multi-model dataset. Support of this dataset is provided by the Office of Science, U.S. Department of Energy. We thank Drs. Andrew Monaghan and William Chapman for their help with the observational data sets, and two anonymous reviewers for their constructive criticisms of our previous manuscript.
- Forster P, Ramaswamy V, Artaxo P, Berntsen T, Betts R, Fahey DW, Haywood J, Lean J, Lowe DC, Myhre G, Nganga J, Prinn R, Raga G, Schulz M, Van Dorland R (2007) Changes in Atmospheric Constituents and in Radiative Forcing. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL (eds) Climate change 2007: the physical science basis. Contribution of working group I to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar
- Hartmann D (1994) Atmospheric general circulation and climate. In: Global physical climatology. Academic Press, London, pp 136–170Google Scholar
- Karpechko AY, Gillett NP, Marshall GJ, Screen JA (2009) Climate impacts of the southern annular mode simulated by the CMIP3 models. J Clim 22:375–3768Google Scholar
- Liu H, Jezek K, Li B, Zhao Z (2001) Radarsat Antarctic mapping project digital elevation model version 2. National Snow and Ice Data Center. Digital media, BoulderGoogle Scholar
- Monaghan AJ, Bromwich DH (2008) Advances in describing recent antarctic climate variability. Bulletin of American Meteorological Society, pp 1295–1306Google Scholar
- Thomas ER, Marshall GJ, McConnell JR (2008) A doubling in snow accumulation in the western Antarctic Peninsula since 1850. Geophys Res Lett 35:L01,706, doi: 10.1029/2007GL032,529
- Thompson DWJ, Wallace JM (2000) Annular modes in the extratropical circulation. Part I: month-to-month variability. J Clim 13:1000–1016Google Scholar