This article summarizes the main features of projected climate impacts on ecosystem services and their implications for focus project areas in Sierra Leone and future national planning. Findings from the latest annual assessment report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) are referred to in order to provide guidance on the way to interpret these results.
The projections for mean annual temperature in Sierra Leone for the end of the 21st century are for significant increases (with very high confidence):
- From the PARCC regional climate projections: increases of 2.5-4˚C
- From global climate models assessed in IPCC AR5: increases of 1.5-3.5˚C
Projections for wet season (July-August-September) total precipitation used in the project are considered plausible/low confidence:
- From the PARCC regional climate projections: changes of +7 to +20%
- From global climate models assessed in IPCC AR5: changes of -15 to +20%
Within the regional climate model projection results:
- Highest temperature increases are expected furthest inland due to the greater distance from the regulating influence of the ocean.
- Generally, larger precipitation increases are projected at or near the coast of Sierra Leone, with smaller increases or slight decreases projected further inland.
Figure 1. Precipitation projections for Sierra Leone. (Top 6 panels) Seasonal total rainfall (mm) in the JAS season, for the baseline period (1971-2000), and projected changes for the near future (2020-2049) and far future (2070-2099), for the RCM models with the lowest and highest sensitivities in the far future time period (for Sierra Leone, these are Q0 and Q14 respectively). (Bottom left panel) Evolution of JAS seasonal total rainfall from 1950-2100 for the median ensemble member of the five models (Q9), as well as the 30-year mean and associated standard deviations for the baseline, near and far future periods defined above. (Bottom right panel) Projected percentage changes for JAS seasonal total rainfall, for the near and far future time periods, for the five RCM experiments as well as 18 CMIP5 GCM experiments using RCP6.0.
- Increases in the fraction of broadleaf tree cover are projected to occur throughout Sierra Leone as a result of the projected temperature increases, although human disturbance projected in future land-use scenarios would restrict this increase (with high confidence)
- Vegetation productivity is also projected to increase as broadleaf tree cover increases, and consequently vegetation carbon storage increases. This is related to increases in minimum temperature, since photosynthesis is not limited by water availability in this region (high confidence)
- There is a large variability in the projections of change in surface runoff with the possibility of an increase towards the end of the century (plausible)
The National Protected Area Authority (NPAA) provided data to PARCC for the Gola Forest as a pilot site. Similar to the rest of the country, in the Gola Rainforest National Park, transboundary with the proposed Gola Forest National Park in Liberia, there is a projected increase in the fraction of broadleaf tree cover, and an increase in the amount of carbon stored in the vegetation (related to temperature; high confidence)
Advice for National Planning
- Indications are that tropical forest in Sierra Leone will become an even more valuable resource for storing carbon in the future, and therefore contributing to mitigation of global climate change. However, including scenarios of future land use shows that human disturbance would significantly reduce this potential and so minimizing this would maximize the mitigation potential of the projected increase in forest carbon storage.
- Given the potentially high impacts to the population of Sierra Leone, despite the projections for an increase in surface water runoff in the far future being regarded as low confidence, these are still a plausible outcome and thus should be considered in planning for the future.
- There is an urgent need to modify and expand the Protected Area Systems to improve their value for biodiversity conservation, climate change mitigation and for other ecosystem services.
Dr. Kolleh Bangura is deeply grateful to Andrew Hartley, Richard Jones and Tamara Janes Met Office Hadley Centre, for providing such important information for the consumption of the scientific and planning communities in Sierra Leone