Progress | Published:

Strong present-day aerosol cooling implies a hot future


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.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Houghton, J. T. et al. in Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge Univ. Press, UK/New York, NY, 2001)

  2. 2

    Murphy, J. M. et al. Quantification of modelling uncertainties in a large ensemble of climate change simulations. Nature 430, 768–772 (2004)

  3. 3

    Stainforth, D. A. et al. Uncertainty in predictions of the climate response to rising levels of greenhouse gases. Nature 433, 403–406 (2005)

  4. 4

    Gregory, J. M., Stouffer, R. J., Raper, S. C. B., Stott, P. A. & Rayner, N. A. An observationally based estimate of the climate sensitivity. J. Clim. 15, 3117–3121 (2002)

  5. 5

    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)

  6. 6

    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)

  7. 7

    Houghton, J. T., Jenkins, G. J. & Ephraums, J. J. Climate Change: The IPCC Assessment (Cambridge Univ. Press, Cambridge, UK, 1990)

  8. 8

    Charlson, R. J. et al. Climate forcing by anthropogenic aerosols. Science 255, 423–430 (1992)

  9. 9

    Cox, P. M., Betts, R. A., Jones, C. D., Spall, S. A. & Totterdell, I. J. Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature 408, 184–187 (2000)

  10. 10

    Friedlingstein, P. et al. Positive feedback between future climate change and the carbon cycle. Geophys. Res. Lett. 28, 1543–1546 (2001)

  11. 11

    Lohmann, U. & Feichter, J. Global indirect aerosol effects: a review. Atmos. Chem. Phys. 5, 715–737 (2005)

  12. 12

    Hansen, J. et al. Climate forcings in Goddard Institute for Space Studies SI2000 simulations. J. Geophys. Res. 107, 4347, doi:10.1029/2001JD001143 (2002)

  13. 13

    Folland, C. K. et al. Global temperature change and its uncertainties since 1861. Geophys. Res. Lett. 28, 2621–2624 (2001)

  14. 14

    Anderson, T. L. et al. Climate forcing by aerosols—a hazy picture. Science 300, 1103–1104 (2003)

  15. 15

    Allen, M. R., Stott, P. A., Mitchell, J. F. B., Schnur, R. & Delworth, T. L. Quantifying the uncertainty in forecasts of anthropogenic climate change. Nature 407, 617–620 (2000)

  16. 16

    Koch, D. Transport and direct radiative forcing of carbonaceous and sulfate aerosols in the GISS GCM. J. Geophys. Res. 106, 20311–20332 (2001)

  17. 17

    Haywood, J. & Boucher, O. Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: A review. Rev. Geophys. 38, 513–543 (2000)

  18. 18

    Knorr, W., Prentice, I. C., House, J. I. & Holland, E. A. Long-term sensitivity of soil carbon turnover to warming. Nature 433, 298–301 (2005)

  19. 19

    Powlson, D. Will soil amplify climate change? Nature 433, 204–205 (2005)

  20. 20

    Alley, R. B. Palaeoclimatic insights into future climate challenges. Phil. Trans. R. Soc. Lond. Ser. A 361, 1831–1848 (2003)

  21. 21

    Jenkyns, H. C., Forster, A., Schouten, S. & Damste, J. S. S. High temperatures in the Late Cretaceous Arctic Ocean. Nature 432, 888–892 (2004)

  22. 22

    Jones, C. D. & Cox, P. M. Constraints on the temperature sensitivity of global soil respiration from the observed interannual variability in atmospheric CO2 . Atmos. Sci. Lett. 2, doi:10.1006/asle.2001.0041 (2001)

  23. 23

    Friedlingstein, P., Dufresne, J. L., Cox, P. M. & Rayner, P. How positive is the feedback between climate change and the carbon cycle? Tellus B 55, 692–700 (2003)

  24. 24

    Levitus, S., Antonov, J. I., Boyer, T. P. & Stephens, C. Warming of the world ocean. Science 287, 2225–2229 (2000)

  25. 25

    Nakicenovic, N. & Swart, R. (eds) Special Report on Emissions Scenarios (Cambridge Univ. Press, Cambridge, UK, 2000)

  26. 26

    O'Neill, B. C. & Oppenheimer, M. Dangerous climate impacts and the Kyoto protocol. Science 296, 1971–1972 (2002)

  27. 27

    Hansen, J. E. A slippery slope: How much global warming constitutes “Dangerous anthropogenic interference”? Clim. Change 68, 269–279 (2005)

  28. 28

    Pope, C. A. et al. Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. J. Am. Med. Assoc. 287, 1132–1141 (2002)

  29. 29

    Jones, C. D., Cox, P. & Huntingford, C. Uncertainty in climate-carbon-cycle projections associated with the sensitivity of soil respiration to temperature. Tellus B 55, 642–648 (2003)

  30. 30

    Stott, P. A. et al. Attribution of twentieth century temperature change to natural and anthropogenic causes. Clim. Dyn. 17, 1–21 (2001)

Download references


C.D.J. was supported by the UK DEFRA Climate Prediction Program.

Author information

Correspondence to Meinrat O. Andreae.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Further reading

Figure 1: Climate sensitivity required to explain the observed 1940–2000 warming as a function of the strength of aerosol radiative cooling.
Figure 2: Temperature change simulated by the simple model for the period 1850 to 2100.
Figure 3: Modelled temperature change and CO 2 increase by 2100 under different development scenarios.
Figure 4: Strength of climate-carbon cycle feedback as a function of climate sensitivity.


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.