Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Unusual Southern Hemisphere tree growth patterns induced by changes in the Southern Annular Mode


Recent changes in the summer climate of the Southern Hemisphere extra-tropics are primarily related to the dominance of the positive phase of the Southern Annular Mode1,2. This shift in the behaviour of the Southern Annular Mode—essentially a measure of the pressure gradient between Southern Hemisphere mid and high latitudes—has been predominantly induced by polar stratospheric ozone depletion2,3,4. The concomitant southward expansion of the dry subtropical belts5,6 could have consequences for forest growth. Here, we use tree-ring records from over 3,000 trees in South America, Tasmania and New Zealand to identify dominant patterns of tree growth in recent centuries. We show that the foremost patterns of growth between 1950 and 2000 differed significantly from those in the previous 250 years. Specifically, growth was higher than the long-term average in the subalpine forests of Tasmania and New Zealand, but lower in the dry-mesic forests of Patagonia. We further demonstrate that variations in the Southern Annular Mode can explain 12–48% of the tree growth anomalies in the latter half of the twentieth century. Tree-ring-based reconstructions of summer Southern Annular Mode indices suggest that the high frequency of the positive phase since the 1950s is unprecedented in the past 600 years. We propose that changes in the Southern Annular Mode have significantly altered tree growth patterns in the Southern Hemisphere.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Long-term variations in tree growth at mid latitudes in the Southern Hemisphere.
Figure 2: Influences of the SAM on regional climate and forest growth.
Figure 3: Variations in regional tree-ring chronologies and the summer SAM.
Figure 4: Summer variations in the SAM for the past 600 years.

Similar content being viewed by others


  1. Thompson, D. W. J., Wallace, J. M. & Hegerl, G. C. Annular modes in the extratropical circulation. Part II: Trends. J. Clim. 13, 1018–1036 (2000).

    Article  Google Scholar 

  2. Thompson, D. W. J. et al. Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change. Nature Geosci. 4, 741–749 (2011).

    Article  Google Scholar 

  3. Polvani, L. M., Waugh, D. J. P., Correa, D. W. & Son, S-W. Stratospheric ozone depletion: The main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. J. Clim. 24, 795–812 (2011).

    Article  Google Scholar 

  4. McLandress, C. et al. Separating the dynamical effects of climate change and ozone depletion. Part II: Southern Hemisphere troposphere. J. Clim. 24, 1850–1868 (2011).

    Article  Google Scholar 

  5. Archer, C. & Caldeira, K. Historical trends in the jet streams. Geophys. Res. Lett. 35, L08803 (2008).

    Google Scholar 

  6. Hu, Y. & Fu, Q. Observed poleward expansion of the Hadley circulation since 1979. Atmos. Chem. Phys. 7, 5229–5236 (2007).

    Article  Google Scholar 

  7. Marshall, G. J. Trends in the southern annular mode from observations and reanalyses. J. Clim. 16, 4134–4143 (2003).

    Article  Google Scholar 

  8. Gillett, N. P., Kell, T. D. & Jones, P. D. Regional climate impacts of the Southern Annular Mode. Geophys. Res. Lett. 33, L23704 (2006).

    Article  Google Scholar 

  9. Aravena, J. C. & Luckman, B. H. Spatio-temporal rainfall patterns in southern South America. Int. J. Climatol. 29, 2106–2120 (2009).

    Article  Google Scholar 

  10. Garreaud, R. D., Vuille, M., Compagnucci, R. & Marengo, J. Present-day South American climate. Palaeogeogr. Palaeoclimatol. Palaeoecol. 281, 180–195 (2009).

    Article  Google Scholar 

  11. Watterson, I. G. Components of precipitation and temperature anomalies and change associated with modes of the Southern Hemisphere. Int. J. Climatol. 29, 809–826 (2009).

    Article  Google Scholar 

  12. Lara, A., Villalba, R. & Urrutia, R. A 400-year tree-ring record of the Puelo River summer-fall streamflow in the Valdivian Rainforest eco-region, Chile. Climatic Change 86, 331–356 (2008).

    Article  Google Scholar 

  13. Boisvenue, C. & Running, S. W. Impacts of climate change on natural forest productivity—evidence since the middle of the 20th century. Glob. Change Biol. 12, 862–882 (2006).

    Article  Google Scholar 

  14. Davis, M. B. & Shaw, R. G. Range shifts and adaptive responses to Quaternary climate change. Science 292, 673–679 (2001).

    Article  Google Scholar 

  15. Hughes, M. K., Swetnam, T. W. & Diaz, H. F. Dendroclimatology, Progress and Prospects. Developments in Paleoenvironmental Research 11 (Springer, 2011).

    Book  Google Scholar 

  16. Cook, E. R. et al. Millennia-long tree-ring records from Tasmania and New Zealand: A basis for modelling climate variability and forcing, past, present and future. J. Quat. Sci. 21, 689–699 (2006).

    Article  Google Scholar 

  17. Boninsegna, J. A. et al. Dendroclimatological reconstructions in South America: A review. Palaeogeogr. Palaeoclimatol. Palaeoecol. 281, 210–228 (2009).

    Article  Google Scholar 

  18. Duncan, R. P., Fenwick, P., Palmer, J. P., McGlone, M. S. & Turney, C. Non-uniform interhemispheric temperature trends over the past 550 years. Clim. Dynam. 35, 1429–1438 (2010).

    Article  Google Scholar 

  19. Hendon, H. H., Thompson, D. W. J. & Wheeler, M. C. Australian rainfall and surface temperature variations associated with the Southern Hemisphere Annular Mode. J. Clim. 20, 2452–2467 (2007).

    Article  Google Scholar 

  20. Jones, J. M. et al. Historical SAM variability. Part I: Century-length seasonal reconstructions. J. Clim. 22, 5319–5345 (2009).

    Article  Google Scholar 

  21. Fogt, R. L. et al. Historical SAM variability. Part II: Twentieth century variability and trends from reconstructions, observations, and the IPCC AR4 models. J. Clim. 22, 5346–5365 (2009).

    Article  Google Scholar 

  22. Karoly, D. J. & Braganza, K. Attribution of recent temperature changes in the Australian region. J. Clim. 18, 457–464 (2004).

    Article  Google Scholar 

  23. Masiokas, M. H. et al. Glacier fluctuations in extratropical South America during the past 1000 years. Palaeogeogr. Palaeoclimatol. Palaeoecol. 281, 242–268 (2009).

    Article  Google Scholar 

  24. Villalba, R. et al. Tree-ring based reconstructions of northern Patagonia precipitation since AD 1600. Holocene 8, 659–674 (1998).

    Article  Google Scholar 

  25. Lara, A. & Villalba, R. A 3,620-year temperature reconstruction from Fitzroya cupressoides tree rings in southern South America. Science 260, 1104–1106 (1993).

    Article  Google Scholar 

  26. Cook, E. R., Briffa, K. R., Meko, D. M., Graybill, D. A. & Funkhouser, G. The segment length curse in long tree-ring chronology development for paleoclimatic studies. Holocene 5, 229–237 (1995).

    Article  Google Scholar 

  27. Meko, D. M. Dendroclimatic reconstruction with time varying subsets of tree indices. J. Clim. 10, 687–696 (1997).

    Article  Google Scholar 

  28. Cook, E. R., Woodhouse, C. A., Eakin, C. M., Meko, D. & Stahle, D. W. Long-term aridity changes in the western United States. Science 306, 1015–1018 (2004).

    Article  Google Scholar 

  29. Esper, J. et al. Long-term drought severity variations in Morocco. Geophys. Res. Lett. 34, L17702 (2007).

    Article  Google Scholar 

  30. Rodionov, S. N. A sequential algorithm for testing climate regime shifts. Geophys. Res. Lett. 31, L09204 (2004).

    Article  Google Scholar 

Download references


This work was supported by the Inter-American Institute for Global Change Research (IAI) CRN 2047, which is supported by the US National Science Foundation (Grant GEO-0452325), by the Argentinean Council of Research and Technology (CONICET), the Argentinean Agency for Promotion of Science and Technology (PICTR02-186) and by FONDECYT Grant Nos 1090479 and 1120965 from the National Research Fund of Chile. G.J.M. is supported by the UK Natural Environment Research Council through the British Antarctic Survey research programme Polar Science for Planet Earth. K.A. is supported by Australian Research Council grant DP120104320 to P. Baker. This work benefited from discussions with P. Sheppard and A. Bahamondez.

Author information

Authors and Affiliations



R.V., A.L., M.H.M., R.U., B.H.L. and G.J.M. designed the study, interpreted the data and wrote the paper. J.A.B, G.J.M., D.A., R.N. and A.M.S. assisted with climate data, data analysis and figures. R.V., I.M., M.S.M. and A.M.S. provided tree-ring chronologies for Argentina. A.L., D.A.C., R.U., C.L., J.C.A., E.C. and A.H. provided tree-ring records for Chile. E.R.C., P.F., K.A. and J.G.P. provided tree-ring chronologies for New Zealand and Tasmania. All authors discussed the results and commented jointly on the manuscript.

Corresponding author

Correspondence to Ricardo Villalba.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 3413 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Villalba, R., Lara, A., Masiokas, M. et al. Unusual Southern Hemisphere tree growth patterns induced by changes in the Southern Annular Mode. Nature Geosci 5, 793–798 (2012).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing Anthropocene

Sign up for the Nature Briefing: Anthropocene newsletter — what matters in anthropocene research, free to your inbox weekly.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing: Anthropocene