Precipitation Data from CMIP5-ESMs-RCPs Experiment: in Weyib River Basin, Southeastern Ethiopia
A. Mean Annual, Seasonal, and Monthly Maximum Temperature Scenarios
Figure 3.3a (top left): Calibration result of SDSM for maximum temperature from average of 3 ESMs (1981- 1993), b (upper right): same as fig 3.3a but for validation period (1994-2005), c (middle left): Calibration result of SDSM for minimum temperature, d (middle right): same as c but for validation period, e (bottom left):
Calibration result of SDSM for precipitation, f (bottom right): same as e but for validation period
Impact of Spatial Data Availability on Climate Change Projection
To characterize how future temperatures and precipitation projection under CMIP5-ESMs- RCP output varies against various averaged arbitrary spatial weather stations found in the Weyib River basin, it is essential to obtain station wise future projections on both temperatures (maximum and minimum), and precipitation. Therefore, for brevity reason, the results are summarized into four cases namely; case I (twelve averaged spatial weather stations), case II (six averaged spatial arbitrary weather stations), case III (three averaged spatial arbitrary weather stations) and case IV (for a single weather station) to describe both temperatures and precipitation.
3.3.3. Scenarios developed for future temperatures and precipitation (2006-2100) for twelve averaged spatial weather stations
the highest mean annual value for maximum temperature and increased by 0.20, 0.32 and 0.42°C (G2M-RCP8.5), 0.20, 0.29 and 0.31°C (G2M-RCP4.5) and 0.22, 0.24 and 0.21°C (G2M-RCP2.6) in the 2020s, 2050s and 2080s time slices respectively; GFDL-ESM2G (G2G), projects the lowest increases in the value of this parameter by 0.04, 0.12 and 0.22°C (G2G-RCP8.5), 0.04, 0.09 and 0.11°C (G2G-RCP4.5) and 0.08, 0.04 and 0.03°C (G2G- RCP2.6) in the 2020s, 2050s and 2080s time slices respectively and CanESM2 (C2), projects an intermediate (median) increase of mean annual maximum temperature by 0.12, 0.22 and 0.32°C (C2-RCP8.5),0.12, 0.19 and 0.21°C (C2-RCP4.5) and 0.16, 0.14 and 0.13°C (C2- RCP2.6) in the 2020s, 2050s and 2080s time slices respectively (Fig. 3.4).
Figure 3.4 Absolute change from baseline simulation of annual maximum temperature in all the ESM-RCP scenarios in the 2020s, 2050s and 2080s time slices
Figure 3.5 Future trend of mean annual maximum temperature (°C) in all the ESM-RCP scenarios The variability of maximum temperature is higher for all ESMs of RCP8.5 than RCP4.5 and RCP2.6, and the future trend for RCP8.5 and RCP4.5 scenarios have been indicated a significantly (at 5% significant level) increasing trend of mean annual maximum temperature
0.00 0.10 0.20 0.30 0.40 0.50
G2M-RCP2.6 G2M-RCP4.5 G2M-RCP8.5 C2-RCP2.6 C2-RCP4.5 C2-RCP8.5 G2G-RCP2.6 G2G-RCP4.5 G2G-RCP8.5
Change from baseline to ESM-RCP scenarios (°C)
ESM-RCP Scenarios
Annual Change in Maximum Temperature under Future Time Slices
2020s 2050s 2080s
22.00 22.50 23.00
2006 2016 2026 2036 2046 2056 2066 2076 2086 2096
Mean annual max temp (°C)
Time (Year)
RCP2.6(CanESM2) RCP2.6(GFDL-ESM2G) RCP2.6(GFDL-ESM2M) RCP4.5(CanESM2) RCP4.5(GFDL-ESM2G) RCP4.5(GFDL-ESM2M) RCP8.5(CanESM2) RCP8.5(GFDL-ESM2G) RCP8.5(GFDL-ESM2M)
until the end of the century (Fig. 3.5 and Table 3.10). Increasing trend but not significant (at 5% significant level) was observed for all ESMs of RCP2.6 scenario. Comparatively, RCP8.5 which is the high emission scenario (i.e., condition of very high GHG concentration level) prevail higher change in maximum temperature trend at the end of the century than the RCP4.5 which is an intermediate emission scenario (i.e., condition of medium to low GHG concentration level) and the RCP2.6 which is the lowest emission scenario (i.e., condition of very low GHG concentration level). For brevity and explanation purposes only the average results of three ESMs for the RCP8.5, RCP4.5, and RCP 2.6 scenarios are given in the case of seasonal and monthly description of maximum and minimum temperatures and precipitation.
The projected (mean of 3 ESMs) seasonal maximum temperature shows a decreasing trend in the dry season in all the three future time slices for the RCP2.6, RCP4.5, and RCP8.5 scenarios (but not for the RCP2.6 scenario which was an increasing trend in the dry season of the 2020s). However, it has shown an increasing trend for both an intermediate and wet seasons in all the three future time slices for the RCP2.6, RCP4.5 and RCP8.5 scenarios (except for the RCP2.6 scenario which was a decreasing trend in a Wet season of the 2020s) as shown in Fig. 3.6a-c and Table 3.7. The absolute changes of maximum temperature from the base period for three scenarios in future time slices for each season have presented in Table 3.7.
Table 3.7 Absolute changes in mean seasonal maximum temperature (°C) at different time slices from the base period
Scenario Seasons in the 2020s Seasons in the 2050s Seasons in the 2050s Dry Intermediate Wet Dry Interm. Wet Dry Interm. Wet RCP2.6
(mean of 3ESMs) +0.275 +0.194 -0.002 -0.017 +0.228 +0.215 -0.002 +0.224 +0.208 RCP4.5
(mean of 3ESMs) -0.012 +0.192 +0.167 -0.001 +0.301 +0.257 -0.001 +0.338 +0.283 RCP8.5
(mean of 3ESMs) -0.007 +0.202 +0.168 -0.036 +0.370 +0.326 -0.051 +0.529 +0.495 The projected (mean of 3 ESMs) monthly maximum temperature has a larger magnitude of increment on the month of Jun 2080s which was 0.58, 0.80 and 1.37°C for RCP2.6, RCP4.5 and RCP8.5 scenarios respectively at the end of the century. On the other hand, the larger decrement on Dec 2080s 0.75, 0.38°C and on Dec 2050s 0.32°C occurred for RCP8.5, RCP4.5, and RCP2.6 scenarios respectively Fig.3.6c, b and a. The absolute change in mean
maximum temperature was observed to be sizable due to there were a substantial increase and decrease of maximum temperature on different months. For instance, in the months of Jan, Feb, Nov and Dec, the decrement of the maximum temperature was observed and an increment on the rest of the months has observed.
Generally, the change in average monthly maximum temperature might range between - 0.25°C on Dec and +0.48°C on Jun for the coming 2020s (2011-2040); -0.50°C on Dec and +0.91°C on Jun for 2050s (2041-2070) and -0.75°C on Dec and +1.37°C on Jun for 2080s (2071-2100) for the RCP8.5 scenario. The change in average monthly maximum temperature for RCP4.5 scenario varies between -0.25°C on Dec and +0.47°C Jun for the coming 2020s; - 0.33°C on Dec and +0.70°C on Jun for 2050s and -0.38°C on Dec and +1.37°C on Jun for 2080s. For the RCP2.6, ranges -0.12°C on Aug and +0.42°C on Dec for 2020s; -0.32°C on Dec and +0.58°C on Jun for 2050s and -0.28 on Dec and +0.55°C on Jun for 2080s. As we can see in Fig 3.6d, there has been shown an increasing trend of maximum temperature in all months and seasons under all RCP scenarios, except in all months of the Dry season which experiences a decreasing trend.
Figure 3.6a (top left): Maximum temperature (monthly and seasonal mean daily) during baseline (1981-2005) simulation and three future time slice under RCP2.6 scenario for twelve averaged spatial stations, b (top right):
same as fig 3.6a but under RCP4.5, c (bottom left): same as fig 3.6a but under RCP8.5, d (bottom right): same as fig 3.6a but without time slice under RCP2.6, RCP4.5 and RCP8.5 scenarios.