The global average temperature has increased significantly since the preindustrial era. Translating global warming into regional scales is crucial to formulate effective environmental and climate policies. A realistic assessment of regional climate change requires high-resolution datasets. We present a new high-resolution (9 km) analysis of historical and future regional warming over the Middle East and North Africa (MENA) using observations, reanalysis products, and statistically downscaled global climate models from the Coupled Model Intercomparison Project (CMIP) Phase 5 and 6. The observed regional temperature change over the MENA subregions appears to be up to three times faster than the global average. Regional warming has already surpassed the 1.5 ℃ and is at the brink of exceeding 2 ℃. By the end of the 21st century, the Arabian Peninsula will warm from 2.66 ± 0.57 to 7.61 ± 1.53 ℃ under the low (SSP1–2.6) and high-end (SSP5–8.5) emission scenarios, respectively. We identify spatially distinct summer and winter warming hotspots. The most prominent spots in summer are the Arabian Peninsula Hotspot Region (APHR) and Algerian Hotspot Region. Major winter hotspots appear over Mauritania in West Arica and the Elburz Mountains. Moreover, APHR has already exceeded 2 °C of warming and will warm by about 9 °C under the high-end emission scenario by the end of the century. The 1.5, 2, 3, and 4 ℃ global warming levels are associated with substantial regional warming of 2.1 ± 0.2, 2.76 ± 0.2, 4.19 ± 0.25, and 5.49 ± 0.38 ℃, respectively, over the Arabian Peninsula.

Tropospheric ozone (O3) is an important greenhouse gas that is also hazardous to human health. O3 is formed photochemically from nitrogen dioxide (NO2) (with oxygen and sunlight), which in turn is generated through oxidation of nitric oxide (NO) by peroxy radicals (HO2 or RO2). The formation of O3 can be sensitive to the levels of its precursors NOx (≡ NO + NO2) and peroxy radicals, e.g., generated by the oxidation of volatile organic compounds (VOCs). A better understanding of this sensitivity will show how changes in the levels of these trace gases could affect O3 levels today and in the future, and thus air quality and climate. In this study, we investigate O3 sensitivity in the tropical troposphere based on in situ observations of NO, HO2 and O3 from four research aircraft campaigns between 2015 and 2023, namely, OMO (Oxidation Mechanism Observations), ATom (Atmospheric Tomography Mission), CAFE Africa (Chemistry of the Atmosphere Field Experiment in Africa) and CAFE Brazil, in combination with simulations using the ECHAM5/MESSy2 Atmospheric Chemistry (EMAC) model. We use the metric α(CH3O2) together with NO to show that O3 formation chemistry is generally NOx-sensitive in the lower and middle tropical troposphere and in a transition regime in the upper troposphere. By distinguishing observations, which are either impacted by lightning or not, we show that NO from lightning is the most important driver of O3 sensitivity in the tropics. Areas affected by lightning exhibit strongly VOC-sensitive O3 chemistry, whereas NOx-sensitive chemistry predominates in regions without lightning impact.

The hotter the climate is, the higher the demand for cooling is, leading to more electricity consumption and CO2 emissions. To understand the effect of future regional warming on the electricity demand and CO2 emissions in the Arabian Peninsula region, we selected a representative country, Qatar, and developed a model that relates daily electricity demand with temperature. By combining this model with temperature projections from of 1 23 the CMIP6 database (bias adjusted and statistically downscaled), as well as GDP and population projections from four SSP scenarios, we calculated Qatar’s demand for electricity until the end of the century. We found an average sensitivity of 1.7 GWh/°C for the electricity demand, equivalent to 0.4 MtCO2/°C for CO2 emissions. The electricity demand is projected to increase by 5 to 35% due to warming alone at the end of this century. Under SSP1, the warming-induced CO2 emissions could be offset by improvements of carbon intensity. Under SSP5, assuming no improvement of carbon intensity, future warming could add 20 to 35% of CO2 emissions per year by the end of the century, with half of the electricity demand related to extremely hot days becoming more frequent in the future. Our findings suggest that it is important to consider additional CO2 emissions arising from future warming in future temperature projections.