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.

The time-transgressive termination of the African Humid Period


During the African Humid Period about 14,800 to 5,500 years ago, changes in incoming solar radiation during Northern Hemisphere summers led to the large-scale expansion and subsequent collapse of the African monsoon. Hydrologic reconstructions from arid North Africa show an abrupt onset and termination of the African Humid Period. These abrupt transitions have been invoked in arguments that the African monsoon responds rapidly to gradual forcing as a result of nonlinear land surface feedbacks. Here we present a reconstruction of precipitation in humid tropical West Africa for the past 20,000 years using the hydrogen isotope composition of leaf waxes preserved in sediments from Lake Bosumtwi, Ghana. We show that over much of tropical and subtropical Africa the monsoon responded synchronously and predictably to glacial reorganizations of overturning circulation in the Atlantic Ocean, but the response to the relatively weaker radiative forcing during the African Humid Period was more spatially and temporally complex. A synthesis of hydrologic reconstructions from across Africa shows that the termination of the African Humid Period was locally abrupt, but occurred progressively later at lower latitudes. We propose that this time-transgressive termination of the African Humid Period reflects declining rainfall intensity induced directly by decreasing summer insolation as well as the gradual southward migration of the tropical rainbelt that occurred during this interval.

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

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Comparison of proxy and model estimates of hydrologic variations at Lake Bosumtwi.
Figure 2: Proxy records of West African monsoon variability over the past 20,000 years.
Figure 3: Hydrologic changes across North Africa over the past 20,000 years.


  1. Boko, M. et al. in Climate Change 2007: Impacts, Adaptation and Vulnerability (eds Parry, M. L. et al.) 433–467 (IPCC, Cambridge Univ. Press, 2007).

    Google Scholar 

  2. Patricola, C. M. & Cook, K. H. Sub-Saharan Northern African climate at the end of the twenty-first century: Forcing factors and climate change processes. Clim. Dynam. 37, 1165–1188 (2011).

    Article  Google Scholar 

  3. Braconnot, P. et al. Results of PMIP2 coupled simulations of the Mid-Holocene and Last Glacial Maximum—Part 2: Feedbacks with emphasis on the location of the ITCZ and mid- and high latitudes heat budget. Clim. Past 3, 279–296 (2007).

    Article  Google Scholar 

  4. Claussen, M. et al. Simulation of an abrupt change in Saharan vegetation in the mid-Holocene. Geophys. Res. Lett. 26, 2037–2040 (1999).

    Article  Google Scholar 

  5. DeMenocal, P. et al. Abrupt onset and termination of the African Humid Period: Rapid climate responses to gradual insolation forcing. Quat. Sci. Rev. 19, 347–361 (2000).

    Article  Google Scholar 

  6. Liu, Z. et al. Simulating the transient evolution and abrupt change of Northern Africa atmosphere–ocean–terrestrial ecosystem in the Holocene. Quat. Sci. Rev. 26, 1818–1837 (2007).

    Article  Google Scholar 

  7. Renssen, H., Brovkin, V., Fichefet, T. & Goosse, H. Simulation of the Holocene climate evolution in Northern Africa: The termination of the African Humid Period. Quat. Int. 150, 95–102 (2006).

    Article  Google Scholar 

  8. Kutzbach, J. E. & Otto-Bliesner, B. The sensitivity of the African–Asian monsoon climate to orbital parameter changes for 9000 years BP in a low-resolution general circulation model. J. Atmos. Sci. 39, 1177–1188 (1982).

    Article  Google Scholar 

  9. Street-Perrott, F. A. & Perrott, R. A. Abrupt climate fluctuations in the tropics: The influence of Atlantic Ocean circulation. Nature 343, 607–612 (1990).

    Article  Google Scholar 

  10. Lezine, A. M., Hely, C., Grenier, C., Braconnot, P. & Krinner, G. Sahara and Sahel vulnerability to climate changes, lessons from Holocene hydrological data. Quat. Sci. Rev. 30, 3001–3012 (2011).

    Article  Google Scholar 

  11. Gasse, F. Hydrological changes in the African tropics since the Last Glacial Maximum. Quat. Sci. Rev. 19, 189–211 (2000).

    Article  Google Scholar 

  12. Prentice, I. C. & Jolly, D. Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa. J. Biogeogr. 27, 507–519 (2000).

    Article  Google Scholar 

  13. Kutzbach, J. E. & Street-Perrot, F. A. Milanovitch forcing of fluctuations in the level of tropical lakes from 18 to 0 kyr BP . Nature 317, 130–134 (1985).

    Article  Google Scholar 

  14. Kutzbach, J. E. & Liu, Z. Response of the African monsoon to orbital forcing and ocean feedbacks in the middle Holocene. Science 278, 440–443 (1997).

    Article  Google Scholar 

  15. Levis, S., Bonan, G. B. & Bonfils, C. Soil feedback drives the mid-Holocene North African monsoon northward in fully coupled CCSM2 simulations with a dynamic vegetation model. Clim. Dynam. 23, 791–802 (2004).

    Article  Google Scholar 

  16. McGee, D., Demenocal, P. B., Winckler, G., Stuut, J. B. W. & Bradtmiller, L. I. The magnitude, timing and abruptness of changes in North African dust deposition over the last 20,000yr. Earth Planet. Sci. Lett. 371–372, 163–176 (2013).

    Article  Google Scholar 

  17. Tierney, J. E. & deMenocal, P. B. Abrupt shifts in Horn of Africa hydroclimate since the Last Glacial Maximum. Science 342, 843–846 (2013).

    Article  Google Scholar 

  18. Liu, Z. et al. Transient simulation of last deglaciation with a new mechanism for Bolling-Allerod warming. Science 325, 310–314 (2009).

    Article  Google Scholar 

  19. Brncic, T. M., Willis, K. J., Harris, D. J. & Washington, R. Culture or climate? The relative influences of past processes on the composition of the lowland Congo rainforest. Phil. Trans. R. Soc. B 362, 229–242 (2007).

    Article  Google Scholar 

  20. Watrin, J., Lezine, A-M. & Hely, C. Plant migration and plant communities at the time of the “green Sahara”. C. R. Geosci. 341, 656–670 (2009).

    Article  Google Scholar 

  21. Garcin, Y. et al. Hydrogen isotope ratios of lacustrine sedimentary n-alkanes as proxies of tropical African hydrology: Insights from a calibration transect across Cameroon. Geochim. Cosmochim. Acta 79, 106–126 (2012).

    Article  Google Scholar 

  22. Lutz, A., Thomas, J. M. & Panorska, A. Environmental controls on stable isotope precipitation values over Mali and Niger, West Africa. Environ. Earth Sci. 62, 1749–1759 (2011).

    Article  Google Scholar 

  23. Shanahan, T. M., Overpeck, J. T., Sharp, W. E., Scholz, C. A. & Arko, J. A. Simulating the response of a closed-basin lake to recent climate changes in tropical West Africa (Lake Bosumtwi, Ghana). Hydrol. Process. 21, 1678–1691 (2007).

    Article  Google Scholar 

  24. McManus, J. F., Francois, R., Gherardi, J. M., Keigwin, L. D. & Brown-Leger, S. Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes. Nature 428, 834–837 (2004).

    Article  Google Scholar 

  25. Stager, J. C., Ryves, D. B., Chase, B. M. & Pausata, F. S. R. Catastrophic drought in the Afro-Asian monsoon region during Heinrich event 1. Science 331, 1299–1302 (2011).

    Article  Google Scholar 

  26. Fleitmann, D. et al. Holocene forcing of the Indian monsoon recorded in a stalagmite from Southern Oman. Science 300, 1737–1739 (2003).

    Article  Google Scholar 

  27. Wang, Y. et al. The Holocene Asian monsoon: Links to solar changes and North Atlantic climate. Science 308, 854–857 (2005).

    Article  Google Scholar 

  28. Haug, G., Hughen, K., Sigman, D., Peterson, L. & Rohl, U. Southward migration of the intertropical convergence zone through the Holocene. Science 293, 1304–1308 (2001).

    Article  Google Scholar 

  29. Niedermeyer, E. M. et al. Orbital- and millennial-scale changes in the hydrologic cycle and vegetation in the western African Sahel: Insights from individual plant wax δD and δ13C. Quat. Sci. Rev. 29, 2996–3005 (2010).

    Article  Google Scholar 

  30. Schefuß, E., Schouten, S. & Schneider, R. Climatic controls on central African hydrology during the past 20,000 years. Nature 437, 1003–1006 (2005).

    Article  Google Scholar 

  31. Nicholson, S. E. The nature of rainfall variability over Africa on time scales of decades to millenia. Glob. Planet. Change 26, 137–158 (2000).

    Article  Google Scholar 

  32. Otto-Bliesner, B. L. et al. Coherent changes of southeastern equatorial and northern African rainfall during the last deglaciation. Science (in the press; 2014).

  33. Vizy, E. K., Cook, K. H., Crétat, J. & Neupane, N. Projections of a Wetter Sahel in the twenty-first century from global and regional models. J. Clim. 26, 4664–4687 (2013).

    Article  Google Scholar 

  34. Christensen, J. H. et al. in Climate Phenomena and their Relevance for Future Regional Climate Change (eds Stocker, T. F. et al.) 1217–1308 (IPCC, Cambridge Univ. Press, 2013).

    Google Scholar 

  35. Blaauw, M. & Christen, J. Flexible paleoclimate age-depth models using an autoregressive gamma process. Bayesian Analsis 6, 457–474 (2011).

    Google Scholar 

  36. Shanahan, T. M. et al. Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: New constraints from laminae analysis and radiocarbon age modeling. Palaeogeogr. Palaeoclimatol. Palaeoecol. 361–362, 49–60 (2012).

    Article  Google Scholar 

  37. Laskar, J. et al. A long term numerical solution for the insolation quantities of the Earth. Astron. Astrophys. 428, 261–285 (2004).

    Article  Google Scholar 

Download references


This work was supported by NSF grants EAR0601998, EAR0602355, AGS0402010, ATM0401908, ATM0214525, ATM0096232 and AGS1243125.

Author information

Authors and Affiliations



Palaeolake-level reconstructions were carried out by T.M.S. and J.T.O. Biomarker analysis was performed by T.M.S. and K.A.H. Analysis of TraCE-21 simulations was conducted by N.P.M. and B.O-B. Field work was conducted by T.M.S., J.T.O., J.P., C.W.H., J.K. and C.A.S. Interpretation was carried out by T.M.S., N.P.M., J.T.O. and K.A.H.

Corresponding author

Correspondence to Timothy M. Shanahan.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 6878 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Shanahan, T., McKay, N., Hughen, K. et al. The time-transgressive termination of the African Humid Period. Nature Geosci 8, 140–144 (2015).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

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