Effects of simulated natural variability on Arctic temperature projections

GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L18708, doi:10.1029/2005GL023404, 2005

Published 06.10.2005

Asgeir Sorteberg

Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway

Tore Furevik

Geophysical Institute, University of Bergen, Bergen, Norway

Helge Drange

Nansen Environmental and Remote Sensing Center, Bergen, Norway

Nils Gunnar Kvamstø

Geophysical Institute, University of Bergen, Bergen, Norway

Abstract

A five-member ensemble with a coupled atmosphere-sea ice-ocean model is used to examine the effects of natural variability on climate projections for the Arctic. The individual ensemble members are initialized from a 300 years control experiment, each starting from different strengths and phases of the Atlantic Meridional Overturning Circulation. The ensemble members are integrated for 80 years with a 1% per year increase in the atmospheric concentration of CO2. The main findings are that on decadal time scales, multi-model spread of estimated temperature changes in the Arctic may potentially be attributed to internal variability of the climate system. During weak CO2 forcing the internal variability may mask the strength of the anthropogenic signals for several decades. The implications of the findings are that attribution of any Arctic climate change trends calculated over a few decades is difficult.

Received 3 May 2005; accepted 15 August 2005; published 23 September 2005.

Index Terms: 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 3337 Atmospheric Processes: Global climate models (1626, 4928); 3349 Atmospheric Processes: Polar meteorology; 1610 Global Change: Atmosphere (0315, 0325); 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513).

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Citation: Sorteberg, A., T. Furevik, H. Drange, and N. G. Kvamstø (2005), Effects of simulated natural variability on Arctic temperature projections, Geophys. Res. Lett., 32, L18708, doi:10.1029/2005GL023404.