Tutorials / Guided use cases
Lake Chad: an opportunity through ecosystem restoration
Background:
The conflict surrounding the Lake continues to be one of the most challenging conflict-traps in the world. Within this conflict, there is a strong seasonal migration of people in search for water, pasture, fuelwood and cultivable land - in other words, access to natural resources to sustain livelihoods. The effects of climate change on the Lake are apparent: temperatures in the region are increasing one and a half times faster than the global average, and precipitation is highly variable and increasing with time. These changes, combined with more extreme weather events due to climate change, drive an increased variability in the size of the lake, which in turn exacerbates the ongoing conflict over limited resources. Lake Chad is no longer shrinking, although it was until not so long ago (2005) (see also this animation), but deforestation and forest degradation in the wider areas around the Lake are increasing as people need wood to cook. Deforestation and forest degradation do not only compound security and safety issues for local populations but can also lead to increased wind speeds and increased soil erosion.
Region:
Lake Chad, West Africa
Topic:
Climate change, Land use change, Restoration
Findings:
There is an opportunity for ecosystem restoration to a productive condition, in the Lake Chad region according to the climatic and vegetation data.
(i) Looking at the local climate of Lake Chad, we can observe that the mean average annual temperature in Lake Chad has increased from 28,5 °C in 1979 to 29,6 °C in 2019 and has an overall linear upward trend.
(ii) The total annual precipitation (mm) varies considerably inter-annually and shows an upward trend (i.e. precipitation is increasing).
(iii) Figure 4 illustrates how the water occurrence intensity between 1984-2018 has evolved, with the northern part of the lake undergoing an increase in the water intensity occurrence. A decrease in water intensity occurrence can be observed on the western side of the Lake on the border with Nigeria, and in the southern part of the lake (in Cameroon and Chad).
(iv) These changes also have an impact on the vegetation in and around Lake Chad. NDVI, shows that the vegetation in Lake Chad is on an upward trend (Figure 5). This is also in line with what we observed previously in terms of climate (warmer temperatures and increased vegetation).
(v) Continuing this line of thought regarding the recovery of vegetation and based on the paper published in Science on the global tree restoration potential, we observe that there is important tree restoration potential around the Lake (Figure 6 and Table 1).
Figure 1: Screenshot of Earth Map with Lake Chad outline and calculations done ‘on the fly’ through the interface.
Figure 2: Average annual temperature (°C) from 1979 - 2019 (based on ERA5 Monthly aggregates - Latest climate reanalysis produced by ECMWF / Copernicus Climate Change Service)
Figure 3: Total annual precipitation (mm) from 1979-2019 (based on CHIRPS Daily: Climate Hazards Group InfraRed Precipitation with Station Data (version 2.0 final))
Figure 4: Change in water occurrence intensity (1984-2018). Green indicates an increase in the intensity of water occurrence while red indicates a decrease in the intensity of water occurrence (based on the European Commission’s Joint Research Centre Global Surface Water Explorer)
Figure 5: Normalized Difference Vegetation Index (NDVI) (Landsat 30m) (based on USGS Landsat 7 Surface Reflectance Tier 1)
Figure 6: Tree restoration potential for Lake Chad (snapshot from Earth Map)(based on Bastin et al. 2019 - The Global tree restoration potential)
Table 1: Tree restoration potential for Lake Chad in hectares (ha) (based on Bastin et al. 2019 - The Global tree restoration potential)