CO2 emission reductions won’t cool atmosphere for centuries – warming “irreversible”

It is often thought that we can overheat the atmosphere in coming decades, then cut CO2 emissions to  cool it down, but this is not an option -  the earth’s temperature will not fall significantly for hundreds of years after we completely stop  CO2 emissions.  So says  a Feb 2009 paper, Irreversible climate change due to carbon dioxide emissions.  Although  Co2 concentrations  would slowly fall,  trapping less heat so tending to cool  the atmosphere,  the warmer oceans would loose a lot of  their ability to cool the air:

Following cessation of CO2 emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years.

Abstract for Solomon et el paper is below,  or see the Full Text (PDF)

Climate will not cool when we stop CO2 emissions

Irreversible climate change due to carbon dioxide emissions

1. Susan Solomon^a,¹,
2. Gian-Kasper Plattner^b,
3. Reto Knutti^c and
4. Pierre Friedlingstein^d

+Author Affiliations

1. 
   
   ^aChemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305;
2. 
   
   ^bInstitute of Biogeochemistry and Pollutant Dynamics and
3. 
   
   ^cInstitute for Atmospheric and Climate Science, ETH CH-8092, Zurich, Switzerland; and
4. 
   
   ^dInstitut Pierre Simon Laplace/Laboratoire des Sciences du Climat et de l’Environnement, Unité Mixte de Recherche 1572 Commissariat à l’Energie Atomique–Centre National de la Recherche Scientifique–Université Versailles Saint-Quentin, Commissariat a l’Energie Atomique-Saclay, l’Orme des Merisiers, 91191 Gif sur Yvette, France

1. Contributed by Susan Solomon, December 16, 2008 (received for review November 12, 2008)

Abstract

The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4–1.0 m if 21st century CO₂ concentrations exceed 600 ppmv and 0.6–1.9 m for peak CO₂ concentrations exceeding ≈1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer.

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