Abstract
Previous studies have highlighted the crucial role of land degradation in tropical African climate. This effect urgently has to be taken into account when predicting future African climate under enhanced greenhouse conditions. Here, we present time slice experiments of African climate until 2025, using a high-resolution regional climate model. A supposable scenario of future land use changes, involving vegetation loss and soil degradation, is prescribed simultaneously with increasing greenhouse-gas concentrations in order to detect, where the different forcings counterbalance or reinforce each other. This proceeding allows us to define the regions of highest vulnerability with respect to future freshwater availability and food security in tropical and subtropical Africa and may provide a decision basis for political measures. The model simulates a considerable reduction in precipitation amount until 2025 over most of tropical Africa, amounting to partly more than 500 mm (20–40% of the annual sum), particularly in the Congo Basin and the Sahel Zone. The change is strongest in boreal summer and basically reflects the pattern of maximum vegetation cover during the seasonal cycle. The related change in the surface energy fluxes induces a substantial near-surface warming by up to 7°C. According to the modified temperature gradients over tropical Africa, the summer monsoon circulation intensifies and transports more humid air masses into the southern part of West Africa. This humidifying effect is overcompensated by a remarkable decrease in surface evaporation, leading to the overall drying tendency over most of Africa. Extreme daily rainfall events become stronger in autumn but less intense in spring. Summer and autumn appear to be characterized by more severe heat waves over Subsaharan West Africa. In addition, the Tropical Easterly Jet is weakening, leading to enhanced drought conditions in the Sahel Zone. All these results suggest that the local impact of land degradation and reduction of vegetation cover may be more important in tropical Africa than the global radiative heating, at least until 2025. This implies that vegetation protection measures at a national scale may directly lead to a mitigation of the expected negative implications of future climate change in tropical Africa.
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References
Bell JL, Sloan LC, Snyder MA (2004) Regional changes in extreme climatic events: a future climate scenario. J Climate 17:81–87
Benson C, Clay EJ (1998) The impact of drought on sub-Saharan economies. World Bank Tech Paper, No. 401, Wold Bank, Washingtion DC
Black E, Slingo J, Sperber KR (2003) An observatonal study of the relationship between excessively strong short rains in coastal East Africa and Indian Ocean SST. Mon Weather Rev 131:74–94
Bounoua L, Collatz GJ, Los SO, Sellers PJ, Dazlich DA, Tucker CJ, Randall DA (2000) Sensitivity of climate to changes in NDVI. J Climate 13:2277–2292
Camberlin P, Janicot S, Poccard I (2001) Seasonality and atmospheric dynamics of the teleconnection between African rainfall and tropical sea-surface temperature: Atlantic vs. ENSO. Int J Climatol 21:973–1004
Changnon SD (2003) Measures of economic impacts of weather extremes. Bull Am Meteorol Soc 84:1231–1235
Christoph M, Speth P, Bollig M, Burkhardt J, Diekkrüger B, Menz G, Rössler M, Schug W (2004) Effizienter und tragähiger Umgang mit Süßwasser anhand zweier Beispiele in Nordwest-bzw. Westafrika. In: Lozán JL, Graßl K, Hupfer P, Menzel L, Schönwiese C-D (Hrsg.): Warnsignal Klima: Genug Wasser für alle? Wissenschaftliche Auswertungen. Hamburg, 282–286
CIESIN (1996) Gridded population density of the world. Consortium for International Earth Science Information Network, Michigan
Clark DB, Xue Y, Harding RJ, Valdes PJ (2001) Modeling the impact of land surface degradation on the climate of tropical North Africa. J Climate 14:1809–1822
Cook KH (1999) Generation of the African easterly jet and its role in determining West African precipitation. J Climate 12:1165–1184
Cullen HM, de Menocal PB (2000) North Atlantic influence on Tigris-Euphrates streamflow. Int J Climatol 20:853–863
Desanker PV, Justice CO (2001) Africa and global climate change: critical issues and suggestions for further research and integrated assessment modeling. Clim Res 17:93–103
Douville H, Chauvin F, Broqua H (2001) Influence of soil moisture on the Asian and African monsoons. Part I: mean monsoon and daily precipitation. J Climate 14:2381–2402
Douville H, Planton S, Royer J-F, Stephenson DB, Tyteca S, Kergoat L, Lafont S, Betts SA (2000) Importance of vegetation feedbacks in doubled-CO2 climate experiments. J Geophys Res 105:14841–14861
Eklundh L, Olsson L (2003) Vegetation index trends for the African Sahel 1982–1999. Geophys Res Lett 30, doi:10.1029/2002GL016772
Feddema JJ, Freire S (2001) Soil degradation, global warming and climate impacts. Clim Res 17: 209–216
Findley SE (1994) Does drought increase migration? A study of migration from rural Mali during the 1983–1985 drought. Int Migr Rev 28:539–553
Fontaine B, Philippon N, Trzaska S, Roucou R (2002) Spring to summer changes in the West African monsoon through NCEP/NCAR reanalyses (1968–1998). J Geophys Res 107, doi:10.1029/2001JD000834
Fowler HJ, Kilsby CG (2003) Implications of changes in seasonal and annual extreme rainfall. Geophys Res Lett 30, doi:10.1029/2003GL017327
Gaertner MA, Christensen OB, Prego JA (2001) The impact of deforestation on the hydrological cycle in the western Mediterranean: an ensemble study with two regional climate models. Clim Dyn 17:857–873
Gallée H, Moufouma-Okia W, Bechtold P, Brasseur O, Dupays I, Marbaix P, Messager C, Ramel R, Lebel T (2004) A high-resolution simulazion of a West African rainy season using a regional climate mode. J Geophys Res 109, doi:10.1029/2003JD004020
Gasse F (2001) Hydrological changes in Africa. Science 292:2259–2260
Gibson R, Kallberg P, Uppala S, Hernandez A, Nomura A, Serrano E (1997) ERA description. Re-Analysis Project Report Series No. 1, European Centre for Medium-Range Weather Forecasts (ECMWF). Reading, UK
Hagemann S, Botzet M, Dümenil L, Machenhauer B (1999) Derivation of global GCM boundary conditions from 1 km land use satellite data. Max-Planck-Inst f Meteor, Report No. 289, Hamburg
Hastenrath S (2000) Interannual and longer term variability of upper-air circulation over the tropical Atlantic and West Africa in boreal summer. Int J Climatol 20:1415–1430
Hennessy KJ, Gregory JM, Mitchell JFB (1997) Changes in daily precipitation under enhanced greenhouse conditions. Clim Dyn 13:667–680
Hosking JRM (1990) L-moments: analysis and estimation of distributions using linear combinations of order statistics. J R Stat Soc B 52:105–124
Houghton JT, Ding Y, Griggs DJ, Noguer M, Van der Linden PJ, Dai X, Maskell K, Johnson CA (eds) (2001) Climate Change 2001. The Scientific Basis. Cambridge
Hulme M, Doherty R, Ngara T, New M, Lister D (2001) African climate change: 1900–2100. Clim Res 17:145–168
Jacob D (2001) A note to the simulation of the annual and interannual variability of the water budget over the Baltic Sea drainage basin. Meteorol Atmos Phys 77:61–74
Jacob D, Van den Hurk BJJM, Andrae U, Elgered G, Fortelius C, Graham LP, Jackson SD, Karstens U, Koepken C, Lindau R, Podzun R, Rockel B, Rubel F, Sass BH, Smith R, Yang X (2001) A comprehensive model intercomparison study investigating the water budget during the PIDCAP period. Meteorol Atmos Phys 77:19–44
Janicot S, Trzaska S, Poccard I (2001) Summer Sahel-ENSO teleconnection and decadal time scale SST variations. Clim Dyn 18:303–320
Jenkins GS, Kamga A, Garba A, Diedhiou A, Morris V, Joseph E (2002) Investigating the West African climate system using global/regional climate models. Bull Am Meteorol Soc 83:583–595
Kharim VV, Zwiers FW (2000) Changes in extremes in an ensemble of transient climate simulations with a coupled atmosphere-ocean GCM. J Climate 13:3760–3788
Knippertz P, Christoph M, Speth P (2003) Long-term precipitation variability in Morocco and the link to the large-scale circulation in recent and future climate. Meteorol Atmos Phys 83:67–88
Krichak SO, Kishcha P, Alpert P (2002) Decadal trends of main Eurasian oscillations and the Eastern Mediterranean precipitation. Theor Appl Climatol 72:209–220
Latif M, Dommenget D, Dima M, Grötzner A (1999) The role of Indian Ocean sea surface temperature in forcing East African rainfall anomalies during December–January 1997/1998. J Climate 12:3497–3504
Le Barbé L, Lebel T, Tapsoba D (2002) Rainfall variability in West Africa during the years 1950–90. J Climate 15:187–202
Long M, Entekhabi D, Nicholson SE (2000) Interannual variability in rainfall, water vapor flux, and vertical motion over West Africa. J Climate 13:3827–3841
Los SO, Collatz GJ, Bounoua L, Sellers PJ, Tucker CJ (2001) Global interannual variations in sea surface temperature and land surface vegetation, air temperature, and precipitation. J Climate 14:1535–1576
Lotsch A, Friedl MA, Anderson BT (2003) Coupled vegetation-precipitation variability observed from satellite and climate records. Geophys Res Lett 30, doi:10.1029/2003GL017506
Maynard K, Royer J-F (2004a) Effects of “realistic” land-cover change on a greenhouse-warmed African climate. Clim Dyn 22:343–358
Maynard K, Royer J-F (2004b) Sensitivity of a general circulation model to land surface parameters in African tropical deforestation experiments. Clim Dyn 22:555–572
McGuffie K, Henderson-Sellers A, Holbrook N, Kothavala Z, Balachova O, Hoekstra J (1999) Assessing simulations of daily temperature and precipitation variability with global climate models for present and enhanced greenhouse climates. Int J Climatol 19:1–26
Meehl GA, Zwiers FW, Evans J, Knutson T, Mearns L, Whetton P (2000) Trends in extreme weather and climate events: issues related to modeling extremes in projections of future climate change. Bull Am Meteorol Soc 81:427–436
Mo K, Bell GD, Thiaw WM (2001) Impact of sea surface temperature anomalies on the Atlantic tropical storm activity and West African rainfall. J Atmos Sci 58:3477–3496
Nakicenovic N, 27 co-authors (2000) Special report on emission scenarios. Intergovernmental Panel on Climate Change, Cambridge
Nicholson SE (2001) Climatic and enviromental change in Africa during the last two centuries. Clim Res 17:123–144
Nicholson SE, Palao IM (1993) A re-evaluation of rainfall variability in the Sahel. Part I. Characteristics of rainfall fluctuations. Int J Climatol 13:371–389
Nicholson SE, Some B, Kone B (2000) An analysis of recent rainfall conditions in West Africa, including the rainy season of the 1997 El Niño and the 1998 La Niña years. J Climatol 13:2628–2640
Paeth H (2004) Key factors in African climate change evaluated by a regional climate model. Erdkunde 58:290–315
Paeth H, Born K, Jacob D, Podzun R (2005) Regional dynamic downscaling over West Africa: model evaluation and comparison of wet and dry years. Meteorol Z 14:349–367
Paeth H, Friederichs P (2004) Seasonality and time scales in the relationship between global SST and African rainfall. Clim Dyn 23:815–837
Paeth H, Hense A (2002) Sensitivity of climate change signals deduced from multi-model Monte Carlo experiments. Clim Res 22:189–204
Paeth H, Hense A (2004) SST versus climate change signals in West African rainfall: 20th century variations and future projections. Clim Change 65:179–208
Paeth H, Hense A (2006) On the linear response of tropical African climate to SST changes deduced from regional climate model simulations. Theor Appl Climatol 83:1–19
Paeth H, Stuck J (2004) The West African dipole in rainfall and its forcing mechanisms in global and regional climate models. Mausam 55:561–582
Pahari K, Murai S (1997) Simulation of forest cover map for 2025 and beyond using remote sensing and GIS. Proceedings of the GIS Development
Palmer TN, Räisänen J (2002) Quantifying the risk of extreme seasonal precipitation events in a changing climate. Nature 415:512–514
Park J-S, Jung H-S, Kim R-S, Oh J-H (2001) Modelling summer extreme rainfall over the Korean peninsula using Wakeby distribution. Int J Climatol 21:1371–1384
Rauthe M, Hense A, Paeth H (2004) A model intercomparison study of climate change signals in extratropical circulation. Int J Climatol 24:643–662
Rodriguez-Fonseca B, de Castro M (2002) On the connection between winter anomalous precipitation in the Iberian Peninsula and North West Africa and the summer subtropical Atlantic sea surface temperature. Geophys Res Lett 29, doi:10.1029/2001GL014421
Roeckner E, Arpe K, Bengtsson L, Christoph M, Claussen M, Dümenil L, Esch M, Giorgetta M, Schlese U, Schulzweida U (1996) The atmospheric general circulation model ECHAM-4: model description and simulation of present-day climate. Max-Planck-Inst f Meteorol, Report No. 218, Hamburg
Rowell DP (2003) The impact of Mediterranean SSTs on the sahelian rainfall season. J Climate 16:849–862
Ruiz-Barradas A, Carton JA, Nigam S (2000) Structure of interannual-to-decadal climate variability in the tropical Atlantic sector. J Climate 13:3285–3297
Saha K, Saha S (2001) African monsoons. Part I: climatological structure and circulation. Mausam 52:479–510
Saravanan R, Chang P (2000) Interaction between tropical Atlantic variability and El Niño-Southern Oscillation. J Climate 13:2177–2194
Schnitzler K-G, Knorr W, Latif M, Bader J, Zeng N (2001) Vegetation feedback on Sahelian rainfall variability in a coupled climate land-vegetation model. Max-Planck-Inst F Meteorol, Report No. 329, 13 pp
Semazzi FHM, Song Y (2001) A GCM study of climate change induced by deforestation in Africa. Clim Res 17:169–182
Sutton RT, Jewson SP, Rowell DP (2000) The elements of climate variability in the tropical Atlantic region. J Climate 13:3261–3284
Taylor CM, Lambin EF, Stephenne N, Harding RJ, Essery RLH (2002) The influence of land use change on climate in the Sahel. J Climate 15:3615–3629
Tiedtke M (1989) A comprehensive mass flux scheme for cumulus parameterization in large scale models. Mon Weather Rev 117:1779–1800
Trenberth KE, Dai A, Rasmussen RM, Parsons DB (2003) The changing character of precipitation. Bull Am Meteorol Soc 84:1205–1217
Ulbrich U, Christoph M (1999) A shift of the NAO and increasing storm track activity over Europe due to anthropogenic greenhouse gas forcing. Clim Dyn 15:551–559
UNEP (2003) Global environmental outlook 3. http://www.grida.no/geo/geo3/english/
Vizy EK, Cook KH (2001) Mechanisms by whioch Gulf of Guinea and Eastern North Atlantic sea surface temperature anomalies can influence African rainfall. J Climate 14:795–821
van den Hurk BJJM, Viterbo P, Los SO (2003) Impact of leaf area index seasonality on the annual land surface evaporation in a global circulation model. J Geophys Res 108, doi:10.1029/2002JD002846
von Storch H, Zwiers FW (1999) Statistical analysis in climate research. Cambridge University Press, Cambridge, UK
Voss R, May W, Roeckner E (2002) Enhanced resolution modelling study on anthropogenic climate change: changes in extremes of the hydrological cycle. Int J Climatol 22:755–777
Wang G, Eltahir AB (2000) Ecosystem dynamics and the Sahel drought. Geophys Res Lett 27: 795–798
Xue Y, Juang H-M, Li W-P, Prince S, DeFries R, Jiao Y, Vasic R (2004) Role of land surface processes in monsoon development: East Asia and West Africa. J Geophys Res 109, doi:10.1029/2003JD003556
Zeng N, Hales K, Neelin JD (2002) Nonlinear dynamics in a coupled vegetation-atmosphere system and implications for desert–forest gradient. J Climate 15:3474–3487
Zeng N, Neelin JD (2000) The role of vegetation-climate interaction and interannual variability in shaping the African Savanna. J Climate 13:2665–2670
Zeng N, Neelin JD, Lau K-M, Tucker CJ (1999) Enhancement of interdecadal climate variability in the Sahel by vegetation interaction. Science 286:1537–1540
Zhao M, Pitman AJ (2002) The impact of land cover change and increasing carbon dioxide on the extreme and frequency of maximum temperature and convective precipitation. Geophys Res Lett 29, doi:10.1029/2002GL013476
Zolina O, Kapala A, Simmer C, Gulev S (2004) Analysis of extreme precipitation over Europe from different reanalyses: a comparative assessment. Glob Planet Change 44:129–161
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Paeth, H., Thamm, HP. Regional modelling of future African climate north of 15°S including greenhouse warming and land degradation. Climatic Change 83, 401–427 (2007). https://doi.org/10.1007/s10584-006-9235-y
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DOI: https://doi.org/10.1007/s10584-006-9235-y