Spatial and temporal patterns of indicators of climate change and variability in the Arab world in the past four decades

A comprehensive assessment of the spatial and temporal patterns of the most common indicators of climate change and variability in the Arab world in the past four decades was carried out. Monthly maximum and minimum air temperature and precipitation amount data for the period 1980–2018 were obtained from the CHELSA project with a resolution of 1 km2, which is suitable for detecting local geographic variations in climatic patterns. This data was analyzed using a seasonal-Kendall metric, followed by Sen’s slope analysis. The findings indicate that almost all areas of the Arab world are getting hotter. Maximum air temperatures increased by magnitudes varying from 0.027 to 0.714 °C/decade with a mean of 0.318 °C/decade while minimum air temperatures increased by magnitudes varying from 0.030 to 0.800 °C/decade with a mean of 0.356 °C/decade. Most of the Arab world did not exhibit clear increasing or decreasing precipitation trends. The remaining areas showed either decreasing or increasing precipitation trends. Decreasing trends varied from −0.001 to −1.825 kg m−2/decade with a mean of −0.163 kg m−2/decade, while increasing trends varied from 0.001 to 4.286 kg m−2/decade with a mean of 0.366 kg m−2/decade. We also analyzed country-wise data and identified areas of most vulnerability in the Arab world.


Study area
The geographic scope of the research (Fig. 1) covers twenty-one adjacent countries within the Arab region, spanning across northern Africa and western Asia.This region also includes the geopolitically disputed Western Sahara region in western Africa.Furthermore, in western Asia, Palestine is comprised of two distinct areas: the Gaza Strip and the West Bank (http:// www.leagu eofar absta tes.net/ ar/ about las/ Pages/ Count ryData.aspx).
Encompassing an area of approximately 12.9 million km 2 , the study area is home to a population exceeding 444.2 million people.Algeria stands as the largest Arab nation, while Bahrain is the smallest.Egypt is the most populous Arab country, with Djibouti having the least population.Despite shared historical, cultural, linguistic, and religious ties, the Arab countries exhibit significant demographic, social, and economic disparities.Urban populations are concentrated around major urban centers, including capital cities.Only the Gulf Cooperation Council (GCC) countries are classified as high-income economies.Jordan, Iraq, and Libya fall into the uppermiddle-income category.Somalia, Sudan, Syria, and Yemen are considered low-income economies, while the remaining Arab countries are classified as lower-middle-income economies.
The study area exhibits a remarkable variation in its topography, ranging from −412 m below mean sea level in the eastern region (at the Dead Sea on the border between Jordan and Palestine) to an elevation of 3957 m above mean sea level in the western area (at Toubkal Peak in the Atlas Mountains of Morocco).This diversity includes prominent mountain ranges such as the Atlas Mountains in northwestern Africa, the Hoggar Mountains in the central Sahara, the Somali Mountains in the northern Horn of Africa, the Yemen-Hadhramout-Dhufar and Hijaz-Asir ranges in the Arabian Peninsula's southern, southwestern, and western parts, the Lebanon Mountains and Zagros-Taurus ranges in the northern Levant, and the Oman Mountains in the eastern Arabian Peninsula.Noteworthy are also the mountain ranges along the western Red Sea shores in Egypt and Sudan, as well as those in the Sinai Peninsula, southwestern Sudan, and southern Libya.
Approximately 97% of the Arab world falls within the arid climate zone, while the remaining 3% occupies the warm temperate climate zone.This warm temperate climate is primarily found in the Atlas Mountains of northwestern Africa and the fertile crescent region in the northern Levant.This climatic variability follows a gradual trend from lower to higher latitudes, with temperatures and precipitation increasing in tandem.
The study area's landscape is predominantly composed of barren lands (82%), followed by shrublands/grasslands (14%), and then croplands (3%).Forests, savannas, and wetlands cover less than 1% of the total area.The region is characterized by several extensive deserts, including the Sahara Desert spanning much of North Africa, the Sinai Desert on the Sinai Peninsula, the Syrian Desert stretching northward from the Arabian Peninsula, and the Arabian Desert encompassing the majority of the Arabian Peninsula.Shrublands and grasslands are noticeable as wide belts stretching from west to east in the northern and southern regions of the Arab world.Croplands are primarily concentrated in the Atlas Mountains of northwestern Africa, along the Nile River and its delta, and in the fertile crescent of northern Levant, with sparse areas in southern Sudan.Patches of savannas can be found in the northern parts of the Atlas Mountains, along the Mediterranean coast, and in the fertile crescent region, as well as parts of Sudan and Somalia.Natural forests are mainly located in mountainous regions and flood plains, while limited wetlands are scattered across Mauritania, Algeria, Tunisia, Egypt, Yemen, and Iraq.

Data and methods
In the present study, global maximum and minimum 2-m air temperature (in Kelvin/10) as well as the global monthly precipitation amount (in kg.m -2 /100) data for the period 1980-2018 were downloaded from the CHELSA website (https:// chelsa-clima te.org/ downl oads/).A total of 1404 files representing 1404 months (39 years × 12 months × 3 variables) were obtained with a Geographic Coordinate System (GCS) referenced to the World Geodetic System 1984 (WGS84) horizontal datum in GeoTIFF format.For maximum and minimum air temperature data, every file representing one month was multiplied by 0.1, converted to degrees Celsius by www.nature.com/scientificreports/subtracting 273.15, projected to the world Mollweide coordinate system, and clipped according to the political borders of the Arab world.For precipitation data, every file representing one month was multiplied by 0.01, projected to the world Mollweide coordinate system, and clipped according to the political borders of the Arab world.Seasonal-Kendall test available in the 'Generate Trend Raster' tool in the geographic information system (GIS) ArcGIS Pro 3.1 (https:// pro.arcgis.com/ en/ pro-app/3.0/ tool-refer ence/ image-analy st/ gener ate-trend-raster.htm) was applied.The goal was to determine whether there are monotonic trends in the three space-time variables maximum and minimum air temperature and precipitation amount in the Arab world in the period 1980-2018.The tool accepts multidimensional raster data as input.Hence, for each of the three variables, a multidimensional Cloud Raster Format (CRF) dataset was formed as follows.(1) A new multidimensional mosaic dataset was created using the 'Create Mosaic Dataset' tool.(2) Time-series rasters (i.e., monthly maximum air temperature or monthly minimum air temperature or monthly precipitation amount) were added to the multidimensional mosaic dataset using the ' Add Rasters to Mosaic Dataset' tool.(3) Multidimensional metadata information was added to the multidimensional mosaic dataset using the 'Build Multidimensional Info' tool.(4) Finally, the multidimensional mosaic dataset was converted into multidimensional CRF using the 'Copy Raster' tool.Each of the three multidimensional CRF datasets that were created was used as input for the 'Generate Trend Raster' tool.The output from applying seasonal-Kendall test is a multidimensional CRF dataset, which comprises maps of Sen's slopes and p-values.These outputs can be used to determine which pixels in the multidimensional time series have a statistically significant (i.e., less than 0.05 significance level) monotonic trend.
The seasonal-Kendall test [46][47][48] is a nonparametric statistical test used to detect monotonic trends in time series data that exhibit a seasonal pattern.It is an extension of the Kendall rank correlation test, which measures the strength of association between two variables by assessing the degree of similarity between the ranks of the corresponding values.The seasonal-Kendall test considers the seasonal nature of the data by dividing the time series into seasonal periods and testing for trends within each period.To conduct the test, the time series data is first divided into seasons of equal length and then the test is applied to each season separately.The test is based on the number of concordant and discordant pairs of observations in each season.A concordant pair is one in which the values of two observations move in the same direction over time, while a discordant pair is one in which the values move in opposite directions.The test statistic is then calculated based on the difference between the number of concordant and discordant pairs.Assuming that the trend is linear, Sen's slope 49 , which is also a nonparametric measure of the magnitude and direction of a monotonic trend in time series data, is then calculated.It is computed as the median of the slopes between all pairs of data points in the time series.
Finally, the most vulnerable areas in the Arab world to increasing air temperatures and decreasing precipitation amounts were identified by applying raster-based overlay analysis (https:// pro.arcgis.com/ en/ pro-app/ latest/ tool-refer ence/ spati al-analy st/ under stand ing-overl ay-analy sis.htm).These areas should have statistically significant increasing monotonic trends of maximum and minimum air temperature and statistically significant monotonic decreasing trends of precipitation amount.First, maps of Sen's slope of maximum air temperature, minimum air temperature, and precipitation amount were reclassified using the 'Reclassify' tool.Pixels with statistically significant positive Sen's slope of maximum air temperature and minimum air temperature and statistically significant negative Sen's Slope of precipitation amount were assigned the value of 1.Then, the reclassified rasters were added using the 'Raster Calculator' tool.Pixels in the resulted output map with values of 3 represent the most vulnerable areas in the Arab world to increasing air temperatures and decreasing precipitation amounts.

Results and discussion
Spatial and temporal patterns of air temperature.Almost all areas of the Arab world (99%) show statistically significant positive monotonic trends (i.e., a general increase over time) of either maximum air temperature (Table 1; Fig. 2) or minimum air temperature (Table 2; Fig. 3).Less than 1% of the areas of the Arab world did not show statistically significant negative nor positive monotonic trends of either maximum air temperature or minimum air temperature.
Regarding maximum air temperature, the magnitude of the increase varies from 0.027 °C/decade (in Yemen) to 0.714 °C/decade (in Syria) with a mean of 0.318 °C/decade.On country-by-country basis, the largest mean of magnitude of increase was calculated for Syria (0.516 °C/decade), followed by Palestine (0.478 °C/decade for West Bank and 0.434 °C/decade for Gaza Strip), and then Iraq (0.432 °C/decade); while the lowest was calculated for Oman (0.177 °C/decade), followed by Western Sahara (0.201 °C/decade), and then Yemen (0.234 °C/decade).
With respect to minimum air temperature, the magnitude of the increase varies from 0.030 °C/decade (in Yemen) to 0.800 °C/decade (in Saudi Arabia) with a mean of 0.356 °C/decade.On country-by-country basis, the largest mean of magnitude of increase was calculated for Kuwait (0.474 °C/decade), followed by Saudi Arabia (0.456 °C/decade), and then Iraq (0.441 °C/decade); while the lowest was calculated for Djibouti (0.092 °C/decade), followed by Somalia (0.131 °C/decade), and then Oman (0.158 °C/decade).Small areas (0.2%) in Oman, namely the areas surrounding the Hajar Mountains in the northern parts of the country, show statistically significant negative monotonic trends (i.e., decrease over time) of minimum air temperature with magnitudes varying from −0.056 to −0.250 °C/decade, and a mean of −0.140 °C/decade.
The largest magnitude of increase of maximum air temperature (greater than 0.5 °C/decade) covers northern Iraq, almost all of Syria, entirety of Palestine, northwestern parts of Jordan, and northern Sinai Peninsula, in addition to scattered patches in northern Saudi Arabia along the borders with Iraq and Kuwait, some parts of the Nile River Delta, southern parts of Sudan, the deserts in southern Egypt and northern Sudan, and Atlas Mountains in Morocco.The spatial pattern of the largest magnitude of increasing trend of minimum air temperature (greater than 0.5 °C/decade) is more scattered with small patches distributed all over different parts of the Arab world, except Oman, Somalia, and northwestern Africa (Tunisia, northern Algeria, and Morocco).Maximum www.nature.com/scientificreports/and minimum air temperature increasing trends and rates for Southern Levant, which encompasses Palestine, Jordan, and southern Syria go along with previously published findings 50,51 .The observed increase in minimum and maximum temperatures match corresponding trends from other parts of the globe.However, the rates of increase tend to be higher for land-locked areas, that is, those located far from main water bodies.This is likely attributed to the fact that most heat goes to oceans and seas because the specific heat of water is higher than land.Coastal areas do not exhibit similar temperature rise because most heat goes into main water bodies since water has higher values of specific heat than land 52 .

Spatial and temporal patterns of precipitation.
Analysis of the spatial and temporal trends of precipitation amounts in the Arab world (Table 3; Fig. 4) allows it to be classified into three regions.The first are areas that show statistically significant negative monotonic trends (i.e., generally, a decrease in precipitation over time).The second are areas that show statistically significant positive monotonic trends (i.e., generally, an increase in precipitation over time).The third are areas in which no statistically significant negative nor positive monotonic trends (i.e., no change in precipitation) can be discerned.
We found that most of the areas of the Arab world (90%) belong to the third type of region where no trends can be observed.Most of these areas (69%) exist in Saudi Arabia (15%), Algeria (14%), Sudan (14%), Libya (12%), Mauritania (7%), and Egypt (7%).The entirety of five countries of the Arab world also belongs to this region, they are: Qatar, Bahrain, Kuwait, Lebanon, and Palestine.The remaining 10% of the areas of the Arab world show either increasing or decreasing trends.
About 7% of the area of the Arab world belongs to the second type of region with increase in precipitation over time.More than half of the areas with increased precipitation can be observed in Algeria (4%).The magnitude of the increase varies from 0.001 kg m −2 /decade (in Mauritania, Algeria, Libya, Egypt, Sudan, Saudi Arabia, and Oman) to 4.286 kg m −2 /decade (in Yemen), with a mean of 0.366 kg m −2 /decade.The regions with largest increase (greater than 1.0 kg m −2 /decade) can be observed mainly along the high mountain ranges in the Arab world.These mountain ranges include the Atlas Mountains in the far west of the Arab world (in Morocco, Algeria, and Tunisia), the southern banks of the Red Sea along the Yemen-Hadhramout Mountains in Yemen, the mountains in Djibouti and northeastern Sudan, the Hajar Mountains in northern Oman, and the high mountain ridges of northeastern Iraqi Kurdistan.Increases of less than 1.0 kg m −2 /decade can be noticed mainly in the African Sahara in central Algeria (Hoggar Mountain Ranges), northern Mauritania, northeastern Sudan along the Red Sea coast, on the opposite side of the sea in central Asir Mountains in western Saudi Arabia, in addition www.nature.com/scientificreports/ to northeastern Oman and northeastern United Arab Emirates along the Gulf of Oman.On country-by-country basis, the largest mean of magnitude of increase was obtained for Yemen (1.153 kg m −2 /decade), followed by Tunisia (1.139 kg m −2 /decade), and then Morocco (1.113 kg m −2 /decade); while the lowest was obtained for Egypt (0.007 kg m −2 /decade), followed by Mauritania (0.011 kg m −2 /decade), and then Libya (0.015 kg m −2 /decade).About 3% of the area of the Arab world belongs to the first type of region, with decreasing amounts of precipitation.Most of the areas with decrease can be noticed in Somalia (1%).The magnitude of the decrease varies from −0.001 kg m −2 /decade (in Libya, Egypt, Sudan, Somalia, and Syria) to −1.825 kg m −2 /decade (in Saudi Arabia) with a mean of −0.163 kg m −2 /decade.The largest magnitudes of decrease (less than −0.4 kg m −2 / decade) can be observed mainly as scattered patches in Somalia, specifically along the coastline of the Gulf of Aden, on the opposite side of the gulf in southeastern Yemen, and in southern Asir mountains in southwestern Saudi Arabia.Decreases in precipitation greater than −0.4 kg m −2 /decade can be observed mainly in northern Libya (along the Mediterranean Sea), northern Egypt (including some parts of the Nile River Delta and northern Sinai Peninsula along the Mediterranean Sea), southwestern Syria and northwestern Jordan (in addition to the eastern bank of the Dead Sea), with scattered patches occurring mainly in northern Somalia, southeastern Yemen, and southwestern Oman.On country-by-country basis, the largest mean of magnitude of decrease was calculated for Saudi Arabia (−0.609 kg m −2 /decade), followed by Somalia (−0.273 kg m −2 /decade), and then Morocco (−0.234 kg m −2 /decade); while the lowest was calculated for Sudan (−0.005 kg m −2 /decade), followed by Mauritania (−0.018 kg m −2 /decade), and then Egypt (−0.027 kg m −2 /decade).Decreasing precipitation in some Arabian territories have been reported by Salameh et al. (2022) 53 who detected declining precipitation trends in spring and autumn.
It is evident from these results that most of the Arab world does not exhibit clear increase or decrease in precipitation.Few exceptions located in the western Mediterranean (i.e., Morocco and Algeria) demonstrate increasing trends in precipitation.Other exceptions in the eastern Mediterranean territories (i.e., in some parts of Libya, Egypt and Syria) exhibit decreasing precipitation trends.This goes along with the findings of Cook et al. (2015) 5 who detected a "SEASAW" precipitation trend in the West-and East-Mediterranean.Areas of most vulnerability and potential impacts.Overlay analysis (Table 4; Fig. 5) identified multiple areas in the Arab world as the most vulnerable to increasing trends of maximum and minimum air temperatures and decreasing trends of precipitation amounts.These areas are scattered in various locations in Mauritania, Western Sahara, Morocco, Libya, Egypt, Jordan, Syria, Oman, Yemen, Saudi Arabia, Sudan, and Somalia with a total area of 336,694.6 km 2 .
Carefully studying these areas, we found that nine of these areas exist in locations where no human populations are present (i.e., VA01, VA02, VA04, VA05, VA06, VA09, VA10, VA12, and VA13).Further, two of the vulnerable areas (i.e., VA14 and VA15) exist in northern and southern Somalia.In these areas, only low-density scattered settlements exist, if at all.Most of these areas are devoid of human population.The remaining four vulnerable areas cover several major urban centers and their surroundings in the Arab world.These urban centers are Agadir in Morocco (VA03); Cairo and Nile River Delta in Egypt (VA07); northeast Dead Sea, north Amman, Salt, Jerash, and Irbid in Jordan (VA08); east Lake Tiberias, Daraa, southeast Damascus, and Homs in Syria (VA08); and Abha, Khamis Mushait, and Al Baha in Saudi Arabia (VA11).
This clear and rapid temperature rise accompanied by lack of precipitation will inevitably lead to an increase in energy demand for cooling and water desalination, as a consequence of anticipated drought.A set of other challenges would also put extra pressure on freshwater demand and air conditioning, including urbanization and rapid population growth, thereby exerting stress on old energy infrastructure in most Arab countries.This will necessitate the construction of additional power plants resulting in direct and indirect emissions of greenhouse gases creating a positive feedback loop.
Several parts of the Arab World including the great Sahara, Jordan, Saudi Arabia, and Gulf states are already in a state of severe water stress due to the harsh climatic conditions that dominate the region as it is influenced by persisting high pressure ridges.Therefore, these territories contribute small portions to the water budget in the region.Communities in these areas rely on ground water resources for agriculture or domestic uses.Wealthy states such as Saudi Arabia and United Arab Emirates fulfill most of their domestic water needs via sea water desalination (energy intensive), but countries like Jordan, Lebanon, Palestine, Somalia, Mauretania, and Yemen lack local energy sources, which puts them in water jeopardy.Therefore, strategic water plans in these countries must cautiously deal with unreliable and unpredicted precipitation trends.Current climatic changes around the glob are largely blamed on global warming which is caused by the accumulation of greenhouse gases in the atmosphere, primarily from human activities such as burning fossil fuels (coal, oil, and natural gas), deforestation, and industrial processes 55 .While the impacts of global warming can vary based on geographic location, socioeconomic factors, and regional policies, many Arab countries may be particularly susceptible to its effects because they exist in regions characterized by arid or semi-arid climates, such as the MENA region.These regions are already prone to high temperatures, limited freshwater resources, and drought.Global warming exacerbates these conditions, leading to increased heatwaves, water scarcity, and desertification.Countries in this region often face water scarcity issues due to their arid climates.Increased temperatures can cause faster evaporation rates from water bodies and soil, leading to further water shortages.Some Arab countries face political instability and conflict, which can hinder their ability to address the impacts of global warming effectively 55 .Additionally, socioeconomic factors may impact a country's capacity to invest in climate adaptation and mitigation strategies.Several countries in the region lack the infrastructure and resources necessary to adapt to cope with the climate change.This can include inadequate water management systems, insufficient disaster preparedness, and limited access to technology for monitoring and mitigating climate-related risks.

Conclusions
The study yielded several key findings regarding climate indicators trends in the Arab world over the past four decades: 1. Maximum Air Temperature Patterns: Nearly all areas in the Arab world experienced statistically significant increasing trends in maximum air temperatures over time.www.nature.com/scientificreports/Morocco, Libya, Egypt, Jordan, Syria, Oman, Yemen, Saudi Arabia, Sudan, and Somalia.These areas covered a total of 336,694.6 km 2 and included major urban centers and their surroundings in Agadir (Morocco), Cairo and the Nile River Delta (Egypt), northeast Dead Sea, north Amman, Salt, Jerash, and Irbid (Jordan), east Lake Tiberias, Daraa, southeast Damascus, and Homs (Syria), and Abha, Khamis Mushait, and Al Baha (Saudi Arabia).

Figure 1 .
Figure 1.Location map of the Arab countries.Included is a list of the areas and populations of the Arab countries.

Figure 2 .
Figure 2. Map showing statistically significant (at 0.05 significance level) Sen's slopes of the seasonal Kendall trend analysis applied on maximum temperature in the Arab world from January 1980 to December 2018.
www.nature.com/scientificreports/Factors influence climate in the Arab world.Most countries in the Arab world are influenced by synoptic meteorological factors and large-scale atmospheric patterns that play a role in shaping the region's climate and can contribute to changes in temperature, precipitation patterns, and other climate-related phenomena54 .They include the subtropical high-pressure systems, Mediterranean Sea influence, north Atlantic oscillation (NAO), Mediterranean oscillation, east Atlantic/west Russia pattern, Saharan air layer, jet streams, tropical and subtropical cyclones, monsoonal flows.As climate change progresses, some of these synoptic meteorological factors may be influenced by shifts in atmospheric circulation and temperature patterns.Changes in sea surface temperatures and atmospheric pressure systems can contribute to alterations in regional climate.

Figure 3 .
Figure 3. Map showing statistically significant (at 0.05 significance level) Sen's slopes of the seasonal Kendall trend analysis applied on minimum temperature in the Arab world from January 1980 to December 2018.

Figure 5 .
Figure 5. Map showing regions of heightened vulnerability in the Arab world (depicted as solid red polygons).These areas are grouped arbitrarily into neighboring clusters, enclosed by ovals of varying sizes.The designations VA01 to VA15 correspond to vulnerable areas 1 through 15.

Table 1 .
Summary statistics of statistically significant (at 0.05 significance level) Sen's slopes of the seasonal Kendall trend analysis applied on monthly maximum temperature in the Arab world from January 1980 to December 2018.

Table 2 .
Summary statistics of statistically significant (at 0.05 significance level) Sen's slopes of the seasonal Kendall trend analysis applied on monthly minimum temperature in the Arab world from January 1980 to December 2018.

Table 3 .
The magnitude of this increase varied across the region, with Yemen showing the smallest increase at 0.027 °C/decade, while Syria had the largest increase at 0.714 °C/decade, with a mean increase of 0.318 °C/decade.Syria had the highest average increase (0.516 °C/ decade), while Oman had the lowest (0.177 °C/decade).2. Minimum Air Temperature Patterns: Similarly, nearly all areas in the Arab world exhibited statistically significant increasing trends in minimum air temperatures over time.The magnitude of increase also varied, ranging from 0.030 °C/decade in Yemen to 0.800 °C/decade in Saudi Arabia, with a mean increase of 0.356 °C/decade.Kuwait had the highest average increase (0.474 °C/decade), while Djibouti had the lowest (0.092 °C/decade).Notably, certain areas around Oman's Hajar Mountains showed statistically significant decreasing trends in minimum air temperatures, ranging from −0.056 to −0.250 °C/decade, with a mean decrease of −0.140 °C/decade.3. Precipitation Patterns: The majority of the Arab world (90%) did not exhibit statistically significant trends in precipitation over the study period.However, around 7% of the region experienced statistically significant increasing trends in precipitation.These increases varied across the Arab world, with Yemen showing the highest increase at 4.286 kg m −2 /decade, and Mauritania, Algeria, Libya, Egypt, Sudan, Saudi Arabia, and Oman showing the lowest increase at 0.001 kg m −2 /decade, with a mean increase of 0.366 kg m −2 /decade.Summary statistics of statistically significant (at 0.05 significance level) Sen's slopes of the seasonal Kendall trend analysis applied on monthly precipitation in the Arab world from January 1980 to December 2018.
Yemen had the highest average increase (1.153 kg m −2 /decade), while Egypt had the lowest (0.007 kg m −2 / decade).Approximately 3% of the Arab world faced statistically significant decreasing trends in precipitation.These decreases also varied across the Arab world, with Saudi Arabia experiencing the highest decrease at −1.825 kg m −2 /decade, and Libya, Egypt, Sudan, Somalia, and Syria experiencing the lowest decrease at −0.001 kg m −2 /decade, with a mean decrease of −0.163 kg m −2 /decade.Saudi Arabia had the highest average decrease (−0.609 kg m −2 /decade), while Sudan the lowest (−0.005 kg m −2 /decade).4. Vulnerable Areas: Vulnerable areas in the Arab world, characterized by increasing maximum and minimum air temperatures and decreasing precipitation trends, were identified in Mauritania, Western Sahara,