4.1 Hot Extremes
The projected changes in MaxTmax across two future periods for two SSPs are depicted in Figure 2. It shows that the highest MaxTmax of 53 °C occurs in Mauritania and some parts of Iraq and Bahrain, while it ranges from 47 to 49 °C in Libya and Egypt. For SSP1-1.9, the projected changes in MaxTmax were greater in the near future than far future. However, the highest increase was above 2.0 °C in the mountainous regions of Algeria and Morocco for SSP1-2.6. The increase in MaxTmax was more than 1.5 °C in the far future for SSP1-2.6. Besides, Figure S1 in the supplementary materials shows the spatial distribution of MeanTmax. The MeanTmax is above 37 °C in almost half of Sudan and some parts of Oman and UAE, whereas it is 35 °C in Mauritania and some parts of Morocco, Algeria, Saudi Arabia, Bahrain, Oman and Yemen. The projected changes in MeanTmax for SSP1-1.9 were almost similar for both future periods, between 1 and 1.5 °C in most parts of MENA. The highest increase was observed in the far future for SSP1-2.6, 1.5 °C in most parts of the study area, with the highest increase of 2 °C in Iraq and Syria.
Figure 3 shows the historical and future projections of p95Tmax. The highest p95Tmax in the study area is 48 °C which occurs in Mauritania and some parts of Morocco and Iraq. In contrast, it is 42 °C in Libya, Egypt, and parts of Sudan. The pattern of projected changes in p95Tmax for SSP1-1.9 in the near and far future was almost similar, except a decrease in p95Tmax was observed from 2.0 °C in the near future to 1.5 °C in the far future in some parts of Saudi Arabia and Bahrain. Furthermore, the greatest projected changes in the far future for SSP1-2.6 were 2.5 °C in mountainous regions of Morocco and Algeria, Iraq, Syria, Kuwait and some parts of Saudi Arabia and Bahrain. Besides, Figure S2 in the supplementary materials shows the highest p99Tmax (above 48 °C) in some parts of Mauritania, Algeria, Iraq, Kuwait, Qatar and Bahrain, while the lowest (44 °C) in some parts of Libya, Egypt and Sudan. The projected changes in p99Tmax showed an increase by 1.5 °C (near future) and 1.0 °C (far future) in some parts of Sudan and Yemen for SSP1-1.9. The increases were 2.0 °C in the near and 1.5°C in the far future in Saudi Arabia and Iraq. The highest increase in p99Tmax was 2.5 °C in both futures for SSP1-2.6 in mountainous regions of Algeria, Morocco, Iraq, Syria, Jordan and Saudi Arabia.
Figure 4 shows the geographical distribution of D40Tmax and its projections. The highest D40Tmax was 135 days in most parts of Mauritania and some parts in Sudan and Saudi Arabia. The lowest D40Tmax (from 30 to 45 days) was in Libya and some parts of Egypt and Algeria. The projected changes in the amount of D40Tmax days showed a rise of 10 to 35 days in different periods for two SSPs. The increase will be more for SSP1-2.6 and 1-1.9. The highest increase was projected for 35 days in some parts of Sudan.
Similarly, the projections for D45Tmax are presented in Figure S3 in the supplementary materials. The results indicated that D45Tmax was 60 days in some parts of Saudi Arabia, Oman and UAE However, D45Tmax was 40 days in some parts of Mauritania and Morocco. The projected changes in D45Tmax were similar for both future periods under SSP1-1.9, ranging from 5 to 20 days in most of the study area. The greatest changes in D45Tmax were 30 days in the far future in most parts of Mauritania, Morocco, Algeria, Iraq and Saudi Arabia for SSP1-2.6.
4.2 Cold Extreme
The geographical distribution of MinTmin for the reference period and projected periods for two SSPs is represented in Figure 5. It revealed that the lowest MinTmin was -20 °C in the mountainous region of Iraq and Syria. However, it was 0 to -8 °C in most study areas. For SSP1-1.9, the projected changes in Min Tmin were greater in the near future than in the far future. However, the highest increase of more than 3 °C in Syria for SSP1-2.6. The increase in MinTmin was 2 °C in the far future for SSP1-2.6. The results for MeanTmin are shown in Figure S4 in the supplementary materials. The highest MeanTmin was above 21 °C in southern Sudan, whereas 13 to 17 °C in central parts, such as Egypt, Libya and Algeria. For SSP1-1.9, the projected changes in MeanTmin were almost similar; however, the peak increase of 2 °C was observed in Saudi Arabia and Iraq by 2059. For SSP1-2.6, the peak increase of 2 ℃ was detected in the far future in the study area.
Figure 6 shows the historical variability and future projections of p05Tmin. The lowest p05Tmin was -4 °C in some small areas of Iraq, Saudi Arabia and Syria. The projected changes in p05Tmin for SSP1-1.9 showed a decrease in p05Tmin from 1.5 °C by 2059 to 1.0 °C by 2099 in most parts of the research area. For SSP1-2.6, the greatest projected changes of 2.5 °C in the future scenario were in Egypt, Sudan, Saudi Arabia and some parts of Mauritania, Morocco and Algeria. Figure S5 in the supplementary materials shows the spatial variability of p01Tmin in the study area for the reference period and its projections. The lowest p01Tmin (-8 °C) was in Saudi Arabia, Iraq, Syria, Libya, Algeria and Morocco, while it ranges from 0 to 8 °C in Egypt, Libya, Morocco, Algeria and Mauritania. Most regions showed an increase of 1.5 °C (near future) and 1.0 °C (far future) for SSP1-1.9. The highest increase of 2 °C was observed for SSP1-2.6 in the far future in Saudi Arabia, Oman, Yemen, Iraq, Mauritania and Morocco.
Figure 7 represents the spatial distribution and its projections of D0Tmin. The D0Tmin was 40 days in some parts of Saudi Arabia, Iraq and Syria, while it ranged between 0 to 30 days in other parts. It showed a decrease in the future. The highest decrease of 9 to 11 days was observed in Saudi Arabia, Iraq, and Syria under both SSPs and future periods. Figure S6 in the supplementary materials shows the geographical distribution of D-5Tmin in the study area for the reference period and its projections. The D-5Tmin was five days. The projected changes in the number of D-5Tmin days demonstrated a 1 to 3 days decline in Saudi Arabia, Iraq and Syria for both future periods and SSP scenarios.
4.2 Population Exposure
Figure 8 shows the projected shifts in population exposure to days with Tmax greater than (40 and 45 °C) in two future periods and SSPs. The results indicated that projected changes in population exposure with D40Tmax and D45Tmax would be greater than 20 million person-days in most parts of Saudi Arabia, Iraq, the UAE, Qatar, Sudan, Yemen, and Syria in the far future for SSP1-2.6, while only 0 to 5 million person-days in the remaining countries.
Figure 9 revealed that the changes in population exposure to MaxTmax would be greater than 7 million persons-°C in most parts of Saudi Arabia, Iraq, UAE, Syria, Yemen, and Sudan in the far future for SSP1-2.6. However, no change in the population exposure to MaxTmax in Morocco and Tunisia in the far future for SSP1-2.6. However, changes in population exposure to MeanTmax were observed similar to MaxTmax in future periods and under SSPs.
Figure 10 indicated that projected changes in population exposure to p95Tmax and p99Tmax were greater than 10 million person-°C in most parts of Saudi Arabia, Iraq, UAE, Syria, Yemen, and Sudan in the far future for SSP1-2.6. However, no change was observed for the same indices in Morocco, Tunisia, some parts of Mauritania, and Egypt in the far future for SSP1-2.6. In contrast, the changes in population to both indices were observed only 0.001 to 1 million person-°C in the remaining parts of the research area in both future periods under both SSPs.
Figure 11 indicated that projected changes in population exposure to D0Tmin were more than 0.15 million person-days in some parts of Saudi Arabia and most parts of Iraq in the far future for SSP1-2.6, while only 0.01 to 0.15 million person-days in the remaining parts. The changes in population exposure to D-5Tmin would either reduce by 0.01 to 0.15 million person-days or remain unchanged in the study area for two future periods and SSPs.
Figure 12 presents projected changes in population exposure to MeanTmin. It shows that more than 4 million people-°C in Saudi Arabia, UAE, Iraq, Syria and Sudan under two future periods and SSPs. In contrast, the changes in population exposure to MinTmin ranged between 0 to 0.1 million person-°C in most areas of the study area in the future for both SSPs.
Figure 13 indicated that projected changes in population exposure to p05Tmin and p01Tmin were almost similar in the pattern for both future periods and scenarios. The changes in population exposure to both hot indices would increase by 5 million person-℃ in some parts of Saudi Arabia, Yemen, UAE, Egypt and Sudan, while only between 0 to 1 million person-℃ in the remaining parts.
The shifts in total population exposure to different hot and cold indices are given in Table 3, respectively. The total population exposure to D40Tmax will increase by 26,775 million person-days for SSP1-2.6 in the far future. The shifts in population exposure to D45Tmax were 11,501 million person-days. However, changes in population exposure to MaxTmax were 12,730 million person-°C. In contrast, the shifts in the total population exposure to cold indices, D0Tmin and D-5Tmin, decreased. The changes in population exposure to D0Tmin and D-5Tmin decreased by 480 and 101 million person-days, respectively. However, changes in population exposure to MeanTmin were 4552 and 5328 by the end of 2059 and 2099 in SSP1-2.6, respectively. Besides, the shifts in population exposure to p05Tmin and p01Tmin were 2654 and 2073 million person-°C, respectively. The increase in population exposure to the hot extreme for SSP1-2.6 will be 0.5 to 5.2% more than SSP1-1.9 in the near future and 1.8 to 18.1% more in the far future. In contrast, the population exposure to the cold extreme for SSP1-2.6 will be 1.7 to 41.3% less than SSP1-1.9 in the near future and 6.5 to more than 100% less in the far future. The findings indicate a substantial rise in population exposure to the hot extreme for only 0.5 °C temperature rise (SSP1-2.6 instead of SSP1-1.9). However, the impacts will be more in reducing the cold extreme than increasing the hot extreme.
Table 3. The total population exposure to different hot and cold indices in two future periods for SSP1-1.9 and 1-2.6.
Hot indices
|
Unit
|
SSP1-1.9
|
SSP1-2.6
|
Near Future
|
Far Future
|
Near Future
|
Far Future
|
D40Tmax
|
Millions person-days
|
20,695
|
23,048
|
21,712
|
26,775
|
D45Tmax
|
8,354
|
9,737
|
8,792
|
11,501
|
D0Tmin
|
-252
|
-36
|
-356
|
-480
|
D-5Tmin
|
-76
|
-53
|
-87
|
-101
|
MeanTmax
|
Millions person-°C
|
7,300
|
8,288
|
7,370
|
8,607
|
MaxTmax
|
11,054
|
12,507
|
11,115
|
12,730
|
p95Tmax
|
9,918
|
11,178
|
10,011
|
11,546
|
p99Tmax
|
10,322
|
11,619
|
10,404
|
11,984
|
MeanTmin
|
4,472
|
5,001
|
4,552
|
5,328
|
MinTmin
|
634
|
712
|
619
|
972
|
p05Tmin
|
2,169
|
2,359
|
2,222
|
2,654
|
p01Tmin
|
1,672
|
1,790
|
1,704
|
2,073
|