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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L19703, doi:10.1029/2007GL031018, 2007

Long term climate implications of 2050 emission reduction targets

Andrew J. Weaver

School of Earth and Ocean Science, University of Victoria, Victoria, British Columbia, Canada


Kirsten Zickfeld

School of Earth and Ocean Science, University of Victoria, Victoria, British Columbia, Canada


Alvaro Montenegro

School of Earth and Ocean Science, University of Victoria, Victoria, British Columbia, Canada


Michael Eby

School of Earth and Ocean Science, University of Victoria, Victoria, British Columbia, Canada


Abstract

A coupled atmosphere-ocean-carbon cycle model is used to examine the long term climate implications of various 2050 greenhouse gas emission reduction targets. All emission targets considered with less than 60% global reduction by 2050 break the 2.0°C threshold warming this century, a number that some have argued represents an upper bound on manageable climate warming. Even when emissions are stabilized at 90% below present levels at 2050, this 2.0°C threshold is eventually broken. Our results suggest that if a 2.0°C warming is to be avoided, direct CO2 capture from the air, together with subsequent sequestration, would eventually have to be introduced in addition to sustained 90% global carbon emissions reductions by 2050.

Received 15 June 2007; accepted 7 September 2007; published 6 October 2007.

Keywords: climate change; carbon cycle; global warming.

Index Terms: 1620 Global Change: Climate dynamics (0429, 3309); 1622 Global Change: Earth system modeling (1225); 1626 Global Change: Global climate models (3337, 4928); 0428 Biogeosciences: Carbon cycling (4806).

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Citation: Weaver, A. J., K. Zickfeld, A. Montenegro, and M. Eby (2007), Long term climate implications of 2050 emission reduction targets, Geophys. Res. Lett., 34, L19703, doi:10.1029/2007GL031018.