Journal ArticleDOI
Uncertainty in predictions of the climate response to rising levels of greenhouse gases.
David A. Stainforth,T. Aina,C. Christensen,Matthew Collins,N. Faull,David J. Frame,J. A. Kettleborough,Simon R. Knight,Andrew J. Martin,James M. Murphy,C. Piani,David M. H. Sexton,Leonard A. Smith,Robert A. Spicer,Alan J. Thorpe,Myles R. Allen +15 more
TLDR
Results from the ‘climateprediction.net’ experiment are presented, the first multi-thousand-member grand ensemble of simulations using a general circulation model and thereby explicitly resolving regional details, finding model versions as realistic as other state-of-the-art climate models but with climate sensitivities ranging from less than 2 K to more than 11’K.Abstract:
In the climateprediction.net project, thousands of individuals have volunteered spare computing capacity on their PCs to help quantify uncertainty in the way our climate responds to increasing levels of greenhouse gases. By running a state-of-the-art climate model thousands of times, it is possible to find out how the model responds to slight changes in the approximations of physical processes that cannot be calculated explicitly. The first batch of results has now been analysed, and surface temperature changes in simulations that capture the climate realistically are ranging from below 2 °C to more than 11 °C. These represent the possible long-term change, averaged over the whole planet, as a result of doubling the levels of atmospheric carbon dioxide in the model. This is the first time that complex models have been found with such a wide range of responses. Their existence will help in quantifying the risks associated with climate change on a regional level. The range of possibilities for future climate evolution1,2,3 needs to be taken into account when planning climate change mitigation and adaptation strategies. This requires ensembles of multi-decadal simulations to assess both chaotic climate variability and model response uncertainty4,5,6,7,8,9. Statistical estimates of model response uncertainty, based on observations of recent climate change10,11,12,13, admit climate sensitivities—defined as the equilibrium response of global mean temperature to doubling levels of atmospheric carbon dioxide—substantially greater than 5 K. But such strong responses are not used in ranges for future climate change14 because they have not been seen in general circulation models. Here we present results from the ‘climateprediction.net’ experiment, the first multi-thousand-member grand ensemble of simulations using a general circulation model and thereby explicitly resolving regional details15,16,17,18,19,20,21. We find model versions as realistic as other state-of-the-art climate models but with climate sensitivities ranging from less than 2 K to more than 11 K. Models with such extreme sensitivities are critical for the study of the full range of possible responses of the climate system to rising greenhouse gas levels, and for assessing the risks associated with specific targets for stabilizing these levels.read more
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Book
The Economics of Climate Change
TL;DR: In this article, the authors present an appropriate way to examine the economics of climate change, given the unique scientific and economic challenges posed, and suggest implications for emissions targets, policy instruments, and global action.
Journal ArticleDOI
Ensemble forecasting of species distributions
Miguel B. Araújo,Mark New +1 more
TL;DR: It is argued that, although improved accuracy can be delivered through the traditional tasks of trying to build better models with improved data, more robust forecasts can also be achieved if ensemble forecasts are produced and analysed appropriately.
Book Chapter
Chapter 12 - Long-term climate change: Projections, commitments and irreversibility
Matthew Collins,R. Knutti,Julie M. Arblaster,J.-L. Dufresne,T. Fichefet,P. Friedlingstein,Xuejie Gao,William J. Gutowski,T. Johns,Gerhard Krinner,Mxolisi Shongwe,C. Tebaldi,A.J. Weaver,M. F. Wehner +13 more
TL;DR: The authors assesses long-term projections of climate change for the end of the 21st century and beyond, where the forced signal depends on the scenario and is typically larger than the internal variability of the climate system.
Journal ArticleDOI
The Potential to Narrow Uncertainty in Regional Climate Predictions
Ed Hawkins,Rowan Sutton +1 more
TL;DR: In this article, a suite of climate models are used to predict changes in surface air temperature on decadal timescales and regional spatial scales, and it is shown that the uncertainty for the next few decades is dominated by model uncertainty and internal variability that are potentially reducible through progress in climate science.
Journal ArticleDOI
Linking climate change modelling to impacts studies: recent advances in downscaling techniques for hydrological modelling
TL;DR: There is a need for a move away from comparison studies into the provision of decision-making tools for planning and management that are robust to future uncertainties; with examination and understanding of uncertainties within the modelling system.
References
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Journal ArticleDOI
Bayesian Calibration of computer models
Marc C. Kennedy,Anthony O'Hagan +1 more
TL;DR: A Bayesian calibration technique which improves on this traditional approach in two respects and attempts to correct for any inadequacy of the model which is revealed by a discrepancy between the observed data and the model predictions from even the best‐fitting parameter values is presented.
Journal ArticleDOI
Constraints on future changes in climate and the hydrologic cycle
Myles R. Allen,William Ingram +1 more
TL;DR: It will be substantially harder to quantify the range of possible changes in the hydrologic cycle than in global-mean temperature, both because the observations are less complete and because the physical constraints are weaker.
Journal ArticleDOI
Quantification of modelling uncertainties in a large ensemble of climate change simulations
James M. Murphy,David M. H. Sexton,David N. Barnett,Gareth S. Jones,Mark J. Webb,Matthew Collins,David A. Stainforth +6 more
TL;DR: A systematic attempt to determine the range of climate changes consistent with these uncertainties, based on a 53-member ensemble of model versions constructed by varying model parameters, which produces a range of regional changes much wider than indicated by traditional methods based on scaling the response patterns of an individual simulation.
Journal ArticleDOI
The impact of new physical parametrizations in the Hadley Centre Climate Model—HADAM3
TL;DR: HadAM3 (Hadley Centre Atmospheric Model version 3) as discussed by the authors is the latest version of the Hadley Centre climate model, which represents a significant improvement over the previous version, HadAM2b.
Book ChapterDOI
The Science of Climate Change
TL;DR: A joint statement issued by the Australian Academy of Sciences, Royal Flemish Academy of Belgium for Sciences and the Arts, and Royal Society (UK).