Drivers of accelerated warming in Mediterranean climate-type regions

Abstract

The near-surface temperature in Mediterranean climate-type regions has increased overall similarly or more rapidly than the global mean rates. Although these regions have comparable climate characteristics and are located at similar latitudes, recent warming acceleration is most pronounced in the Mediterranean Basin. Here, we investigate the contributions of several climate drivers to regional warming anomalies. We consider greenhouse gases, aerosols, solar irradiance, land–atmosphere interactions, and natural climate variability modes. Our results highlight the dominant role of anthropogenic greenhouse gas radiative forcing in all Mediterranean climate-type regions, particularly those in the northern hemisphere. In the Mediterranean Basin, the recent warming acceleration is largely due to the combined effect of declining aerosols and a negative trend in near-surface soil moisture. While land-atmosphere feedbacks are also important in other locations (e.g., California and Southern Africa), this synergy is unique in the Mediterranean Basin. These two regional climate drivers have natural and anthropogenic components of equivalent importance. Such feedbacks are not fully resolved in the current regional climate projections.

Atmospheric Processes over the Broader Mediterranean Region: Effect of the El Niño–Southern Oscillation?

“…Nevertheless, compared to the downward trend in scatterers (SAOD) in the atmosphere, the upward trends in DAOD and AAOD suggest an increasingly larger rise in dust and absorbing particles. A recent study also noted the declining trend in TAOD over the Mediterranean [32]. Raptis et al [95] found a −1.7% trend per year for TAOD 440 over Athens, Greece, in the period 2008-2018; this value is −0.72% per year in our case.…”

“…In a study from the 1980s, Ropelewski and Halpert [31] found a close relationship between the El Niño phases and the precipitation patterns over Australia, the Americas, the Indian sub-continent, and Africa. On the other hand, Urdiales-Flores et al [32] showed that the Mediterranean Basin bas been warming, over the last 120 years , more rapidly than the global rate; they attributed this warming amplification to the combined effect of reduced aerosol loading and a decrease in soil moisture over the region. Chiacchio and Wild [33] attributed the all-sky solar radiation changes over Europe in the period 1970-2000 to the NAO and more specifically to the cloud-cover variability associated with the NAO phases; they also indicated the role of aerosols in this process.…”

“…Conversely, Pace et al [98] discovered an average value of 0.24 for TAOD 495.7 from their own radiometer measurements made during the period of July 2001 to September 2003 on the Italian island of Lampedusa; this result is very close to our average of 0.213. Urdiales-Flores et al [32] investigated the drivers that are causing a warming acceleration over the Mediterranean in the last 120 years and found a combined effect of declining AOD and decreasing soil moisture. Their conclusion is in accordance with the declining trend in TAOD 550 shown in Figure 12 of the present study.…”

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

“…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.…”

“…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.…”