Climate Risk Management in Finnish Development Cooperation - Gaia

Figure 8. Composite (average of 19 Global Climate Models/GCMs) change in temperature (oC) relative
to 1961-1990 normal for A1B emission scenario. Source NAPA.
With regards to changes in precipitation there is
likely to be an increase in annual mean rainfall in
Eastern Africa. 32 However, in comparison to
temperature, rainfall projections for Ethiopia are a
lot less certain. While showing a tendency for slightly
wetter conditions in the future (figure 9, providing
one projection from NAPA), both increases and
decreases in rainfall are predicted by the different
models and scenarios, with considerable regional and
seasonal differences.
Figure 9. One projection for future change in annual rainfall. Composite percentage change (%) in
rainfall relative to 1961-1990 normal for A1B emission scenario. Source NAPA.
The considerable regional and seasonal differences between climate model simulations of
future rainfall conditions warrants caution in interpreting the results. The usage of a range of
scenarios to represent the uncertainty in future climate change impacts has been identified
as one useful option to deal with these uncertainties in adaptation decision making. 33 The
wide range of potential rainfall changes (regionally and seasonally) is presented in the
projections is highlighted in the diversity of results in different scenario work. 34
32 IPCC fourth assessment report, 2007.
33 Uncertainties in rainfall projection are partly explained by: i) difficulties of GCMs to reproduce the mechanisms
responsible for precipitation, ii) model limitations to simulate the different teleconnections and feedback
mechanisms, which are responsible for rainfall variability in Africa, and iii) other factors that complicate African
climatology (e.g. at present there are no clear indications of future behaviour in El Niño, associated with dry wet
seasons in Ethiopia, and the Indian Ocean Dipole, which is sometimes associated with flood events during
October to December, and their possible influence on Ethiopian climate. Conway, D et al (2007). In general
Model simulations show wide disagreements in projected changes in the amplitude of future El Niño events
(Christensen et al., 2007). East Africa’s seasonal rainfall can be strongly influenced by ENSO, and this contributes
to uncertainty in climate projections, particularly in the future inter-annual variability, for this region.
34 See e.g. Conway, D et al (2007).
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