Declining uncertainty in transient climate response as CO2 forcing dominates future climate change

Abstract

Carbon dioxide has exerted the largest portion of radiative forcing and surface temperature change over the industrial era, but other anthropogenic influences have also contributed1,2. However, large uncertainties in total forcing make it difficult to derive climate sensitivity from historical observations3,4,5,6,7. Anthropogenic forcing has increased between the Fourth and Fifth Assessment Reports of the Intergovernmental Panel of Climate Change (IPCC; refs 1, 8), although its relative uncertainty has decreased. Here we show, based on data from the two reports, that this evolution towards lower uncertainty can be expected to continue into the future. Because it is easier to reduce air pollution than carbon dioxide emissions and because of the long lifetime of carbon dioxide, the less uncertain carbon dioxide forcing is expected to become increasingly dominant. Using a statistical model, we estimate that the relative uncertainty in anthropogenic forcing of more than 40% quoted in the latest IPCC report for 2011 will be almost halved by 2030, even without better scientific understanding. Absolute forcing uncertainty will also decline for the first time, provided projected decreases in aerosols occur. Other factors being equal, this stronger constraint on forcing will bring a significant reduction in the uncertainty of observation-based estimates of the transient climate response, with a 50% reduction in its uncertainty range expected by 2030.

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Figure 1: Anthropogenic forcing for four phases of IPCC reports and two RCPs.
Figure 2: Decadal RF change between 1970 and 2010 and for 2020 to 2030 for two RCPs.
Figure 3: Time evolution in RF and standard deviation in RF.
Figure 4: Uncertainty in TCR with RF and temperature change.

References

  1. 1

    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).

  2. 2

    IPCC Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, 2013).

  3. 3

    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).

  4. 4

    Andreae, M. O., Jones, C. D. & Cox, P. M. Strong present-day aerosol cooling implies a hot future. Nature 435, 1187–1190 (2005).

  5. 5

    Knutti, R. & Hegerl, G. C. The equilibrium sensitivity of the Earth’s temperature to radiation changes. Nature Geosci. 1, 735–743 (2008).

  6. 6

    Otto, A. et al. Energy budget constraints on climate response. Nature Geosci. 6, 415–416 (2013).

  7. 7

    Roe, G. H. & Armour, K. C. How sensitive is climate sensitivity? Geophys. Res. Lett. 38, L14708 (2011).

  8. 8

    Forster, P. et al. in Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) 129–134 (IPCC, Cambridge Univ. Press, 2007).

  9. 9

    Urban, N. M. et al. Historical and future learning about climate sensitivity. Geophys. Res. Lett. 41, 2543–2552 (2014).

  10. 10

    Isaksen, I. S. A. et al. Atmospheric composition change: Climate–chemistry interactions. Atmos. Environ. 43, 5138–5192 (2009).

  11. 11

    Raes, F., Liao, H., Chen, W. T. & Seinfeld, J. H. Atmospheric chemistry–climate feedbacks. J. Geophys. Res. 115, D12121 (2010).

  12. 12

    Shindell, D. T. et al. Improved attribution of climate forcing to emissions. Science 326, 716–718 (2009).

  13. 13

    Crook, J. A. & Forster, P. M. A balance between radiative forcing and climate feedback in the modeled 20th century temperature response. J. Geophys. Res. 116, D17108 (2011).

  14. 14

    Huber, M. & Knutti, R. Anthropogenic and natural warming inferred from changes in Earth’s energy balance. Nature Geosci. 5, 31–36 (2012).

  15. 15

    Hansen, J., Sato, M., Kharecha, P. & von Schuckmann, K. Earth’s energy imbalance and implications. Atmos. Chem. Phys. 11, 13421–13449 (2011).

  16. 16

    Ramanathan, V., Crutzen, P. J., Kiehl, J. T. & Rosenfeld, D. Atmosphere—aerosols, climate, and the hydrological cycle. Science 294, 2119–2124 (2001).

  17. 17

    Boucher, O. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 571–657 (IPCC, Cambridge Univ. Press, 2013).

  18. 18

    Haywood, J. & Schulz, M. Causes of the reduction in uncertainty in the anthropogenic radiative forcing of climate between IPCC (2001) and IPCC (2007). Geophys. Res. Lett. 34, L20701 (2007).

  19. 19

    Boucher, O. & Haywood, J. On summing the components of radiative forcing of climate change. Clim. Dynam. 18, 297–302 (2001).

  20. 20

    Forest, C. E. et al. Quantifying uncertainties in climate system properties with the use of recent climate observations. Science 295, 113–117 (2002).

  21. 21

    Knutti, R., Stocker, T. F., Joos, F. & Plattner, G. K. Constraints on radiative forcing and future climate change from observations and climate model ensembles. Nature 416, 719–723 (2002).

  22. 22

    Peters, G. P. et al. The challenge to keep global warming below 2 degrees C. Nature Clim. Change 3, 4–6 (2013).

  23. 23

    Murphy, D. M. Little net clear-sky radiative forcing from recent regional redistribution of aerosols. Nature Geosci. 6, 258–262 (2013).

  24. 24

    Shindell, D. T. Inhomogeneous forcing and transient climate sensitivity. Nature Clim. Change 4, 274–277 (2014).

  25. 25

    Forster, P. M. et al. Evaluating adjusted forcing and model spread for historical and future scenarios in the CMIP5 generation of climate models. J. Geophys. Res. 118, 1139–1150 (2013).

  26. 26

    Meinshausen, M. et al. Greenhouse-gas emission targets for limiting global warming to 2 degrees C. Nature 458, 1158–1162 (2009).

  27. 27

    Prather, M. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 1395–1445 (IPCC, Cambridge Univ. Press, 2013).

  28. 28

    Van Vuuren, D. P. et al. The representative concentration pathways: An overview. Climatic Change 109, 5–31 (2011).

  29. 29

    Skeie, R. B. et al. Anthropogenic radiative forcing time series from pre-industrial times until 2010. Atmos. Chem. Phys. 11, 11827–11857 (2011).

  30. 30

    Shindell, D. T. et al. Radiative forcing in the ACCMIP historical and future climate simulations. Atmos. Chem. Phys. 13, 2939–2974 (2013).

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Acknowledgements

G.M. was supported by the Norwegian Research Council project SLAC (208277). Norwegian Research Council project number 230619 supported a personal visit for P.F.

Author information

G.M., F-M.B. and D.S. initiated the study with additional contributions on the design of the study from P.F. and O.B. G.M., O.B., F-M.B., P.F. and D.S. performed the analysis and wrote the paper.

Correspondence to Gunnar Myhre.

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The authors declare no competing financial interests.

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Myhre, G., Boucher, O., Bréon, F. et al. Declining uncertainty in transient climate response as CO2 forcing dominates future climate change. Nature Geosci 8, 181–185 (2015). https://doi.org/10.1038/ngeo2371

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