A key uncertainty in projecting future climate change is the magnitude of equilibrium climate sensitivity (ECS), that is, the eventual increase in global annual average surface temperature in response to a doubling of atmospheric CO2 concentration. The lower bound of the likely range for ECS given in the IPCC Fifth Assessment Report (AR5; refs 1, 2) was revised downwards to 1.5 °C, from 2 °C in its previous report3, mainly as an effect of considering observations over the warming hiatus—the period of slowdown of global average temperature increase since the early 2000s. Here we analyse how estimates of ECS change as observations accumulate over time and estimate the contribution of potential causes to the hiatus. We find that including observations over the hiatus reduces the most likely value for ECS from 2.8 °C to 2.5 °C, but that the lower bound of the 90% range remains stable around 2 °C. We also find that the hiatus is primarily attributable to El Niño/Southern Oscillation-related variability and reduced solar forcing.
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Bindoff, N. L. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 867–952 (IPCC, Cambridge Univ. Press, 2013).
Collins, M. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 1029–1136 (IPCC, Cambridge Univ. Press, 2013).
Meehl, G. A. et al. in Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) 747–845 (IPCC, Cambridge Univ. Press, 2013).
Huber, M. & Knutti, R. Natural variability, radiative forcing and climate response in the recent hiatus reconciled. Nature Geosci. 7, 651–656 (2014).
Meehl, G. A., Arblaster, J. M., Fasullo, J. T., Hu, A. & Trenberth, K. E. Model-based evidence of deep-ocean heat uptake during surface-temperature hiatus periods. Nature Clim. Change 1, 360–364 (2011).
Kosaka, Y. & Xie, S-P. Recent global-warming hiatus tied to equatorial Pacific surface cooling. Nature 501, 403–407 (2013).
Trenberth, K. E. & Fasullo, J. T. An apparent hiatus in global warming? Earth’s Future 1, 19–32 (2013).
Chen, X. & Tung, K-K. Varying planetary heat sink led to global-warming slowdown and acceleration. Science 345, 897–903 (2014).
Santer, B. D. et al. Volcanic contribution to decadal changes on tropospheric temperature. Nature Geosci. 7, 185–189 (2014).
Kaufmann, R. K., Kauppi, H., Mann, M. L. & Stock, J. H. Reconciling anthropogenic climate change with observed temperature 1998–2008. Proc. Natl Acad. Sci. USA 108, 11790–11793 (2011).
Aldrin, M. et al. Bayesian estimation of climate sensitivity based on a simple climate model fitted to observations of hemispheric temperatures and global ocean heat content. Environmetrics 23, 253–271 (2012).
Otto, A. et al. Energy budget constraints on climate response. Nature Geosci. 6, 415–416 (2013).
Balmaseda, M. A., Trenberth, K. E. & Källén, E. Distinctive climate signals in reanalysis of global ocean heat content. Geophys. Res. Lett. 40, 1754–1759 (2013).
Trenberth, K. E., Caron, J. M., Stepaniak, D. P. & Worley, S. The evolution of ENSO and global atmospheric surface temperatures. J. Geophys. Res. 107, http://dx.doi.org/10.1029/2000JD000298 (2002)
Huber, M., Beyerle, U. & Knutti, R. Estimating climate sensitivity and future temperature in the presence of natural climate variability. Geophys. Res. Lett. 41, 2086–2092 (2014).
Urban, N. M., Holden, P. B., Edwards, N. R., Sriver, R. L. & Keller, K. Historical and future learning about climate sensitivity. Geophys. Res. Lett. 41, 2543–2552 (2014).
Skeie, R. B., Berntsen, T., Aldrin, M., Holden, M. & Myhre, G. A lower and more constrained estimate of climate sensitivity using updated observations and detailed radiative forcing time series. Earth Syst. Dynam. 5, 139–175 (2014).
Smith, T. M., Reynolds, R. W., Peterson, T. C. & Lawrimore, J. Improvements to NOAA’s historical merged land–ocean surface temperature analysis (1880–2006). J. Clim. 21, 2283–2296 (2008).
Cowtan, K. & Way, R. G. Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends. Q. J. R. Meteorol. Soc. 140, 1935–1944 (2014).
Annan, J. D. & Hargreaves, J. C. On the generation and interpretation of probabilistic estimates of climate sensitivity. Climatic Change 104, 423–436 (2011).
Forest, C. E., Stone, P. H., Sokolov, A. P., Allen, M. R. & Webster, M. D. Quantifying uncertainties in climate system properties with the use of recent climate observations. Science 295, 113–117 (2002).
Oppenheimer, M., O’Neill, B. C. & Webster, M. Negative learning. Climatic Change 89, 155–172 (2008).
Hannart, A., Ghil, M., Dufresne, J-L. & Naveau, P. Disconcerting learning on climate sensitivity and the uncertain future of uncertainty. Climatic Change 119, 585–601 (2013).
Meinshausen, M. et al. The RCP greenhouse gas concentrations and their extension from 1765 to 2300. Climatic Change 109, 213–241 (2011).
Myhre, G. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 659–740 (IPCC, Cambridge Univ. Press, 2013).
Crowley, T. J. & Unterman, M. B. Technical details concerning development of a 1200-yr proxy index for global volcanism. Earth Syst. Sci. Data 5, 187–197 (2013).
Sato, M., Hansen, J. E., McCormick, M. P. & Pollack, J. B. Stratospheric aerosol optical depth, 1850–1990. J. Geophys. Res. 98, 22987–22994 (1993).
Levitus, S. et al. World ocean heat content and thermosteric sea level change (0–2000 m) 1955–2010. Geophys. Res. Lett. 39, L10603 (2012).
Tomassini, L., Reichert, P., Knutti, R., Stocker, T. F. & Borsuk, M. E. Robust Bayesian uncertainty analysis of climate system properties using Markov chain Monte Carlo methods. J. Clim. 20, 1239–1254 (2007).
Gelman, A. et al. Bayesian Data Analysis (Chapman & Hall/CRC, 2004).
D.J.A.J. wants to thank the Swedish Energy Agency and Carl Bennet AB for financial support. C.T. was supported by the Regional and Global Climate Modeling Program (RGCM) of the US Department of Energy’s Office of Science (BER), Cooperative Agreement DE-FC02-97ER62402. O.H. was supported by the Knut and Alice Wallenberg Foundation and the Swedish Research Council. C. Azar is acknowledged for useful comments.
The authors declare no competing financial interests.
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Johansson, D., O’Neill, B., Tebaldi, C. et al. Equilibrium climate sensitivity in light of observations over the warming hiatus. Nature Clim Change 5, 449–453 (2015). https://doi.org/10.1038/nclimate2573
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