Constraints on radiative forcing and future climate change from observations and climate model ensembles
- 1 April 2002
- journal article
- Published by Springer Science and Business Media LLC in Nature
- Vol. 416 (6882), 719-723
- https://doi.org/10.1038/416719a
Abstract
The assessment of uncertainties in global warming projections is often based on expert judgement, because a number of key variables in climate change are poorly quantified. In particular, the sensitivity of climate to changing greenhouse-gas concentrations in the atmosphere and the radiative forcing effects by aerosols are not well constrained, leading to large uncertainties in global warming simulations. Here we present a Monte Carlo approach to produce probabilistic climate projections, using a climate model of reduced complexity. The uncertainties in the input parameters and in the model itself are taken into account, and past observations of oceanic and atmospheric warming are used to constrain the range of realistic model responses. We obtain a probability density function for the present-day total radiative forcing, giving 1.4 to 2.4 W m-2 for the 5-95 per cent confidence range, narrowing the global-mean indirect aerosol effect to the range of 0 to -1.2 W m-2. Ensemble simulations for two illustrative emission scenarios suggest a 40 per cent probability that global-mean surface temperature increase will exceed the range predicted by the Intergovernmental Panel on Climate Change (IPCC), but only a 5 per cent probability that warming will fall below that range.Keywords
This publication has 25 references indexed in Scilit:
- What is 'dangerous' climate change?Nature, 2001
- Detection of Anthropogenic Climate Change in the World's OceansScience, 2001
- Attribution of twentieth century temperature change to natural and anthropogenic causesClimate Dynamics, 2001
- External Control of 20th Century Temperature by Natural and Anthropogenic ForcingsScience, 2000
- Optimal detection and attribution of climate change: sensitivity of results to climate model differencesClimate Dynamics, 2000
- Quantifying the uncertainty in forecasts of anthropogenic climate changeNature, 2000
- Warming of the World OceanScience, 2000
- Causes of twentieth-century temperature change near the Earth's surfaceNature, 1999
- Surface air temperature and its changes over the past 150 yearsReviews of Geophysics, 1999
- A search for human influences on the thermal structure of the atmosphereNature, 1996