The development of realistic scenarios of land cover change in tropical Africa for the period PROMISE Work Package 2100 Impact of Land-Use Changes on Future Monsoon Climates The development of realistic scenarios of land cover change in tropical Africa for the period 1960 – 2050 Dermot O’Regan CEH Wallingford

The development of realistic scenarios of land cover change in tropical Africa for the period Study Objectives WP2100 To use global and/or regional control and scenario integrations to address the impact of land use changes (e.g. deforestation) on monsoon climates. The sensitivity of the results to the representation of hydrological and land-surface processes will be investigated. CEH Wallingford Scenarios for land cover change from will be generated for sub-Saharan Africa based on simple assumptions about population growth, land use practice, and current rates of deforestation. Gridded changes in generic vegetation classes (forest, cropland, pasture etc.) will be converted to changes in land surface parameters which can be applied consistently in different GCMs. Comparison between modelled responses will be used to aid in the identification of common mechanisms and model short-comings.

The development of realistic scenarios of land cover change in tropical Africa for the period Presentation Outline 2. Study Method - present the methodology and some results of this part of WP The Problem: Data and Understanding - highlight the problems of obtaining reliable estimates of land cover and land cover change essential for global change monitoring

The development of realistic scenarios of land cover change in tropical Africa for the period Data and Understanding Land Cover & Land Use Reliable, comprehensive and timely information on global land cover and land use is essential in the context of global change research (DeFries and Townsend 1994) Land Cover & Land Use Change Understanding the dynamics of land-use and land-cover has increasingly been recognised as one of the key research imperatives in global environmental change research (Lambin 2001)

The development of realistic scenarios of land cover change in tropical Africa for the period Figure 1: A comparison of estimates of extent of ten cover types derived from three existing ground-based datasets of global land cover (from DeFries & Townshend 1994)

The development of realistic scenarios of land cover change in tropical Africa for the period Study Method collate data relating to ‘present’ land cover and deforestation rates in the study region identify the area of each land cover type, by country, both in terms of actual hectarage and as a percentage of total (national) land area generate scenarios of past and future land cover in the region map land cover classes into GCM functional types – tree, shrub, grass, bare soil - for use in different GCMs make data available for integration with meteorological and hydrological components of CEH work

The development of realistic scenarios of land cover change in tropical Africa for the period Study Region: Tropical Africa Central Africa (6) D.R.C. Congo Gabon Eq. Guinea Cameroon C.A.R. West Africa (16) Senegal Gambia Guinea Bissau Guinea Sierra Leone Liberia Ivory Coast Ghana Togo Benin Nigeria Chad Niger Burkina Faso Mali Mauritania

The development of realistic scenarios of land cover change in tropical Africa for the period Global Land Cover Data Sources  FAO  FAOSTAT  Global Forest Resources Assessment (FRA1990, FRA2000)  World Forestry Inventory (1953, 1958, 1963)  UNEP  Environmental Data Report ( biennial)  World Bank  World Development Report (1977 – annual) World Resources Institute (WRI) World Resources (1984-biennial) Central Intelligence Agency (CIA) World Factbook ( ) USGS Global Land Cover Characteristics Database (IGBP Land Cover Classification)

The development of realistic scenarios of land cover change in tropical Africa for the period Varying Estimates of Land Cover Problems with land cover and land cover change estimation: - definitions of land cover types - reliable and consistent observation and inventory - inaccessibility (ground or satellite based methods) - remote sensing classification

The development of realistic scenarios of land cover change in tropical Africa for the period FAO Global Forest Resources Assessment 2000 (FRA2000) 1990 Land Cover Estimates

The development of realistic scenarios of land cover change in tropical Africa for the period FAO Global Forest Resources Assessment 2000 (FRA2000) CountryTotal Forest 1990 (% of total land area) Total Forest 2000 (% of total land area) Forest Cover Change 1990 –2000 (% annual rate) Dem. Rep. Congo Congo Cameroon Benin Ivory Coast Guinea

The development of realistic scenarios of land cover change in tropical Africa for the period Scenarios of Land Cover Change Using the FRA 2000 baseline data, scenarios of land cover were generated for 1961, 2025 and 2050 based on FRA 2000 land cover classification the change in forest extent was estimated for each country in the region (increase back to 1960s, decrease into 21st century) For the ‘1961’ scenario forest extent was altered according to land cover change estimates from the Environmental Data Report 1991/92 (UNEP) covering the period 1966 – 1988 Future forest cover scenarios were generated based on two models, and applied to the years 2025 and A ‘BAU’ (business-as-usual) model gives forest cover estimates based on the scenario of a continuation of current rates of deforestation, as determined by FRA 2000 A ‘population growth’ model generated an alternative future forest cover scenario whereby annual deforestation rates ( and ) are based on a relationship between population density and cumulative forest loss as published by Pahari and Murai (1999)

The development of realistic scenarios of land cover change in tropical Africa for the period Scenarios of Land Cover Change Forest Loss

The development of realistic scenarios of land cover change in tropical Africa for the period Scenarios of Land Cover Change The extent of land cover within the other two classes was then increased, or decreased, accordingly. A partition of 40% “other wooded land” and 60% “other land” was applied, based on the proximate causes and specific agricultural practices causing deforestation in tropical Africa as assessed by Geist and Lambin (2001).

The development of realistic scenarios of land cover change in tropical Africa for the period Scenarios of Land Cover Change Land Cover Change

The development of realistic scenarios of land cover change in tropical Africa for the period Mapping Land Cover Classes to GCM Functional Types Following expert guidance, FRA2000 land cover classes were converted to functional types – tree, shrub, grass, bare soil - for application in different GCMs FRA Moist Tropical Sudaneo % Vegetation % Soil % Vegetation % Soil Land Cover Class TreeShrubGrassTotalTreeShrubGrassTotal Forest Other Wooded Land Other Land

The development of realistic scenarios of land cover change in tropical Africa for the period Conclusions Reliable, consistent, and timely data on the dynamics of land cover and land use are an essential component in global change research Currently, estimates of land cover vary greatly and the understanding of the drivers of land use change remains a key issue For this study scenarios for land cover change from were generated for a study region of tropical Africa based on simple assumptions about population growth, land use practice, and current rates of deforestation Will results show that climate and hydrological models are sensitive to the estimated changes in land cover and land use presented?