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Author(s): Shepherd JG, Caldeira K, Cox PM, Haigh J, Keith DW, Launder B, Mace GM, MacKerron G, Pyle J, Rayner S, Redgwell C, Watson AJ
Published: September, 2009
Publisher: The Royal Society
Tags: Overview
URL: http://royalsociety.org/policy/publications/2009/geoengineering-climate/
Abstract: Man-made climate change is happening and its impacts and costs will be large, serious and unevenly spread. The impacts may be reduced by adaptation and moderated by mitigation, especially by reducing emissions of greenhouse gases. However, global efforts to reduce emissions have not yet been sufficiently successful to provide confidence that the reductions needed to avoid dangerous climate change will be achieved. This has led to growing interest in geoengineering, defined here as the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change.
Author(s): Andreae MO, Jones CD, Cox PM
Published: June, 2005
Publisher: Nature
DOI: 10.1038/nature03671
Tags: Tropospheric Aerosols, Climate Science
URL: http://www.nature.com/nature/journal/v435/n7046/full/nature03671.html
Abstract: Atmospheric aerosols counteract the warming effects of anthropogenic greenhouse gases by an uncertain, but potentially large, amount. This in turn leads to large uncertainties in the sensitivity of climate to human perturbations, and therefore also in carbon cycle feedbacks and projections of climate change. In the future, aerosol cooling is expected to decline relative to greenhouse gas forcing, because of the aerosols' much shorter lifetime and the pursuit of a cleaner atmosphere. Strong aerosol cooling in the past and present would then imply that future global warming may proceed at or even above the upper extreme of the range projected by the Intergovernmental Panel on Climate Change.
Author(s): Cox PM, Betts RA, Jones CD, Spall SA, Totterdell IJ
Published: November, 2000
Publisher: Nature
DOI: 10.1038/35041539
Tags: Climate Science, Carbon Cycle, Climate Modelling
URL: http://www.nature.com/nature/journal/v408/n6809/full/408184a0.html
Abstract: The continued increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being absorbed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO2 concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon–climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a 'business as usual' scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C yr-1 is balanced by the terrestrial carbon source, and atmospheric CO2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models2, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback.
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