Systematic climate shifts have been linked to multidecadal variability in observed sea surface temperatures in the North Atlantic Ocean1. These links are extensive, influencing a range of climate processes such as hurricane activity2 and African Sahel3,4,5 and Amazonian5 droughts. The variability is distinct from historical global-mean temperature changes and is commonly attributed to natural ocean oscillations6,7,8,9,10. A number of studies have provided evidence that aerosols can influence long-term changes in sea surface temperatures11,12, but climate models have so far failed to reproduce these interactions6,9 and the role of aerosols in decadal variability remains unclear. Here we use a state-of-the-art Earth system climate model to show that aerosol emissions and periods of volcanic activity explain 76 per cent of the simulated multidecadal variance in detrended 1860–2005 North Atlantic sea surface temperatures. After 1950, simulated variability is within observational estimates; our estimates for 1910–1940 capture twice the warming of previous generation models but do not explain the entire observed trend. Other processes, such as ocean circulation, may also have contributed to variability in the early twentieth century. Mechanistically, we find that inclusion of aerosol–cloud microphysical effects, which were included in few previous multimodel ensembles, dominates the magnitude (80 per cent) and the spatial pattern of the total surface aerosol forcing in the North Atlantic. Our findings suggest that anthropogenic aerosol emissions influenced a range of societally important historical climate events such as peaks in hurricane activity and Sahel drought. Decadal-scale model predictions of regional Atlantic climate will probably be improved by incorporating aerosol–cloud microphysical interactions and estimates of future concentrations of aerosols, emissions of which are directly addressable by policy actions.
This is a preview of subscription content, access via your institution
Open Access articles citing this article.
Scientific Reports Open Access 18 November 2022
Early warning signal for a tipping point suggested by a millennial Atlantic Multidecadal Variability reconstruction
Nature Communications Open Access 02 September 2022
Nature Communications Open Access 29 August 2022
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Baines, P. & Folland, C. K. Evidence for a rapid global climate shift across the late 1960s. J. Clim. 20, 2721–2744 (2007)
Goldenberg, S. B., Landsea, C. W., Nunez, A. M. M. & Gray, W. M. The recent increase in Atlantic hurricane activity: causes and implications. Science 293, 474–479 (2001)
Ackerley, D. et al. Sensitivity of twentieth-century Sahel rainfall to sulfate aerosol and CO2 forcing. J. Clim. 24, 4999–5014 (2011)
Hoerling, M. J., Hurrell, J., Eischeid, J. & Phillips, A. Detection and attribution of 20th century Northern and Southern African rainfall change. J. Clim. 19, 3989–4008 (2006)
Knight, J. R., Folland, C. K. & Scaife, A. A. Climate impacts of the Atlantic Multidecadal Oscillation. Geophys. Res. Lett. 33, L17706 (2006)
Knight, J. R. The Atlantic Multidecadal Oscillation inferred from the forced climate response in coupled general circulation models. J. Clim. 22, 1610–1625 (2009)
Knight, J. R., Allan, R. J., Folland, C. K., Vellinga, M. & Mann, M. E. A signature of persistent natural thermohaline circulation cycles in observed climate. Geophys. Res. Lett. 32, L20708 (2005)
Sutton, R. T. & Hodson, D. L. R. Atlantic Ocean forcing of North American and European summer climate. Science 309, 115–118 (2005)
Ting, M., Kushnir, Y., Seager, R. & Li, C. Forced and internal twentieth-century SST trends in the North Atlantic. J. Clim. 22, 1469–1481 (2009)
Trenberth, K. E. & Shea, D. J. Atlantic hurricanes and natural variability in 2005. Geophys. Res. Lett. 33, L12704 (2006)
Mann, M. E. & Emanuel, K. A. Atlantic hurricane trends linked to climate change. Eos 87, 233–244 (2006)
Evan, A. T., Vimont, D. J., Heidinger, A. K., Kossin, J. P. & Bennartz, R. The role of aerosols in the evolution of tropical North Atlantic Ocean temperature anomalies. Science 324, 778–781 (2009)
Folland, C. K., Palmer, T. N. & Parker, D. E. Sahel rainfall and worldwide sea temperatures, 1901–85. Nature 320, 602–607 (1986)
Zhang, R. & Delworth, T. L. Impact of Atlantic multidecadal oscillations on India/Sahel rainfall and Atlantic hurricanes. Geophys. Res. Lett. 33, L17712 (2006)
Enfield, D. B., Nunez, A. M. M. & Trimble, J. P. The Atlantic multidecadal oscillation and its relation to rainfall and river flows in the continental US. Geophys. Res. Lett. 28, 2077–2080 (2001)
Curtis, S. The Atlantic multidecadal oscillation and extreme daily precipitation over the US and Mexico during the hurricane season. Clim. Dyn. 30, 343–351 (2008)
Chylek, P., Folland, C. K., Lesins, G. & Dubey, M. K. Twentieth century bipolar seesaw of the Arctic and Antarctic surface air temperatures. Geophys. Res. Lett. 37, L08703 (2010)
Dong, B. W., Sutton, R. T. & Scaife, A. A. Multidecadal modulation of El Nino-Southern Oscillation (ENSO) variance by Atlantic Ocean sea surface temperatures. Geophys. Res. Lett. 33, L08705 (2006)
Chen, W., Dong, B. & Lu, R. Impact of the Atlantic Ocean on the multidecadal fluctuation of El Nino–Southern Oscillation–South Asian monsoon relationship in a coupled general circulation model. J. Geophys. Res. 115, D17109 (2010)
Bjerknes, J. Atlantic air-sea interaction. Adv. Geophys. 10, 1–82 (1964)
Kerr, R. A. A North Atlantic climate pacemaker for the centuries. Science 288, 1984–1985 (2000)
Otterå, O. H., Bentsen, M., Drange, H. & Suo, L. External forcing as a metronome for Atlantic multidecadal variability. Nat. Geosci. 3, 688–694 (2010)
Chang, C. Y., Chiang, J. C. H. & Wehner, M. F. Friedman, A. & Ruedy, R. Sulfate aerosol control of tropical Atlantic climate over the 20th century. J. Clim. 24, 2540–2555 (2011)
Collins, W. J. et al. Development and evaluation of an Earth-system model - HadGEM2. Geosci. Model Dev. 4, 1051–1075 (2011)
Bellouin, N. et al. Aerosol forcing in the Climate Model Intercomparison Project (CMIP5) simulations by HadGEM2-ES and the role of ammonium nitrate. J. Geophys. Res. 116, D20206 (2011)
Jones, C. D. et al. The HadGEM2-ES implementation of CMIP5 centennial simulations. Geosci. Model Dev. 4, 543–570 (2011)
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)
Lohmann, U. & Feichter, J. Global indirect aerosol effects: a review. Atmos. Chem. Phys. 5, 715–737 (2005)
Quaas, J. et al. Aerosol indirect effects - general circulation model intercomparison and evaluation with satellite data. Atmos. Chem. Phys. 9, 8697–8717 (2009)
Sato, M., Hansen, J. E., McCormick, M. P. & Pollack, J. B. Stratospheric aerosol optical depths, 1850–1990. J. Geophys. Res. 98, 22987–22994 (1993)
We are grateful for discussion and input from D. Smith, D. Sexton, J. Murphy, M. Palmer, C. Roberts and J. Knight during the analysis and writing of this paper. We acknowledge the modelling groups, the Program for Climate Model Diagnosis and Intercomparison and the WCRP’s Working Group on Coupled Modelling for their roles in making available the WCRP CMIP3 multimodel data set. Support of this data set is provided by the Office of Science, US Department of Energy. The authors were supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101) and the EU FP7 THOR project.
The authors declare no competing financial interests.
About this article
Cite this article
Booth, B., Dunstone, N., Halloran, P. et al. Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability. Nature 484, 228–232 (2012). https://doi.org/10.1038/nature10946
This article is cited by
Nature Climate Change (2022)
Nature Communications (2022)
Predictability of South-Asian monsoon rainfall beyond the legacy of Tropical Ocean Global Atmosphere program (TOGA)
npj Climate and Atmospheric Science (2022)
Potential fire risks in South America under anthropogenic forcing hidden by the Atlantic Multidecadal Oscillation
Nature Communications (2022)
Nature Communications (2022)