3.2.2. Future Temperature Change

Under RCP4.5, the homogeneity tests detected break-points at different dates, but they got an agreement under RCP8.5 (Figure 10). Under the intermediate scenario, the Pettitt test indicated that, from the period 2018–2031 to 2032–2050, temperature may increase by 0.36 ◦C. On the other side, SNH test projected an increase of 0.39 ◦C from 2018–2027 to 2028–2050. For the high pathway scenario, both tests agreed on an increase of 0.87 ◦C from the period 2018–2038 to 2039–2050.

**Figure 10.** Pettitt test (**upper panel**) and SNH test (**lower panel**) performed on temperature under RCP4.5 and RCP8.5.

Regardless of the scenario used, an overall significant increasing trend in temperature is expected by 2050 (Table 5).

Figure 11 depicts anomalies of temperature under RCP4.5 and RCP8.5.

For both emission scenarios, the number of years above normal is higher compared to the number of years below normal. Therefore, future climate in Mono river watershed is projected to be warmer by 2050. Such an increasing trend by 2050 has been reported by Nelson et al. [46] in Togo. Similarly, Oyerinde [47] reported a consistently increasing trend in temperature over the Niger River Basin, 5% to 10% under RCP4.5 and 5% to 20% under RCP8.5, using an ensemble model from eight regional climate models. In the Massili basin of Burkina Faso, Bontogho [29] reported an increase in temperature by 1.8 ◦C (RCP4.5) and 3.0 ◦C (RCP8.5) from 1971 to 2050 using the regional model HIRHAM5. Badou [48] reported a temperature increase of up to 0.48 ◦C under RCP4.5 and up to 0.45 ◦C under RCP8.5 using

the REMO model in the Benin part of Niger River basin. Overall, all models and scenarios considered by several authors converge to a moderate to high increase of temperature all over the world.


**Table 5.** Results of Mann-Kendall test on annual temperature under RCP4.5 and RCP8.5.

**Figure 11.** Temperature anomaly under RCP4.5 (**a**) and RCP8.5 (**b**).

#### **4. Conclusions**

This paper examined the trend in annual rainfall and annual temperature of Mono river watershed over the observation period 1981–2010 and by 2050 using the regional model REMO under RCP4.5 and RCP8.5. It also assessed the monthly pattern of rainfall over the same periods. During the last three decades, rainfall and temperature have been increasing all over the Mono River watershed. By 2050 and under emission scenarios RCP4.5 and RCP8.5, annual rainfall is projected to be characterized by high variability, whereas a significant increasing trend is projected for annual temperature (warmer future climate). For each of the three defined regions (south, center and north), and under both emission scenarios, the seasonal cycle of rainfall is expected to change: In the southern part, the first peak is projected to reduce slightly, whereas the second peak is expected to increase and shift to October; however, in the central and northern parts, it is expected that there will be late onset of rainfall and higher peaks. In addition, the seasonal cycle of rainfall in the central part is expected to shift from a transitional regime to a unimodal one. Moreover, on a monthly scale, the northern part of the watershed is expected to record the highest increase and decrease in rainfall regardless of the emission scenario considered. These considerable changes in the monthly rainfall of the northern part are expected to occur globally in the dry season, thus indicating potential extreme events. Considering the projected trends and patterns for rainfall and temperature over Mono watershed by 2050, it is recommended that experts identify and implement relevant adaptation strategies.

**Author Contributions:** A.E.L., N.R.H., D.F.B. and C.A.B. designed the study, developed the methodology and wrote the original manuscript. N.R.H. performed the field work, data collection and computer analyzis, meanwhile C.A.B. contributed to results analysis and interpretation. Overall the authors contributed equally to this paper.

**Funding:** This research was funded by the West African Science Service Center for Climate Change and Adapted Land use (WASCAL).

**Acknowledgments:** Authors thank the German Federal Ministry of Education who funded the Master Degree of Nina Rholan Houngue through the West African Science Service Center for Climate Change and Adapted Land use (WASCAL). We thank the ESGF grid (http://esg-dn1.nsc.liu.se/esgf-web-fe/) which provided the CORDEX-Africa future climate projections.

**Conflicts of Interest:** The authors declare no conflict of interest.
