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On Avoiding Dangerous Anthropogenic Interference with the Climate System: Formidable Challenges Ahead

TitleOn Avoiding Dangerous Anthropogenic Interference with the Climate System: Formidable Challenges Ahead
Publication TypeJournal Article
Year of Publication2008
AuthorsRamanathan, V., and Y. Feng
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue38
Pagination14245-14250
Date PublishedSEP 23 2008
ISBN Number0027-8424
KeywordsCHINA, committed, EMISSIONS, global warming, sensitivity, trends
Abstract

The observed increase in the concentration of greenhouse gases (GHGs) since the preindustrial era has most likely committed the world to a warming of 2.4 degrees C (1.4 degrees C to 4.3 degrees C) above the preindustrial surface temperatures. The committed warming is inferred from the most recent Intergovernmental Panel on Climate Change (IPCC) estimates of the greenhouse forcing and climate sensitivity. The estimated warming of 2.4 degrees C is the equilibrium warming above preindustrial temperatures that the world will observe even if GHG concentrations are held fixed at their 2005 concentration levels but without any other anthropogenic forcing such as the cooling effect of aerosols. The range of 1.4 degrees C to 4.3 degrees C in the committed warming overlaps and surpasses the currently perceived threshold range of 1 degrees C to 3 degrees C for dangerous anthropogenic interference with many of the climate-tipping elements such as the summer arctic sea ice, Himalayan-Tibetan glaciers, and the Greenland Ice Sheet. IPCC models suggest that approximate to 25% (0.6 degrees C) of the committed warming has been realized as of now. About 90% or more of the rest of the committed warming of 1.6 degrees C will unfold during the 21st century, determined by the rate of the unmasking of the aerosol cooling effect by air pollution abatement laws and by the rate of release of the GHIGs-forcing stored in the oceans. The accompanying sea-level rise can continue for more than several centuries. Lastly, even the most aggressive CO2 mitigation steps as envisioned now can only limit further additions to the committed warming, but not reduce the already committed GHGs warming of 2.4 degrees C.

DOIDOI 10.1073/pnas.0803838105
Reference number

87

Short TitleOn Avoiding Dangerous Anthropogenic Interference with the Climate System: Formidable Challenges Ahead
Citation Key87