The anthropogenic causes of climate change have been scientifically demonstrated, resulting in an increasingly various pattern of meteorological and hydrological events around the planet, from heat waves to coastal flooding during extreme tides and storms, flooding from more intense precipitation events, and severe drought periods (Mann and Gleick, 2015; IPCC, 2023).

Industrial agriculture contributes significantly to climate change, especially in its release of methane and nitrous oxide from livestock and land use change (Clark et al., 2020). Agriculture, like all biological processes and human activities, is under siege from the impacts of climate change and in an unknown scenario (Ripple et al., 2023). Climate change may affect crops’ productivity with changing precipitation and temperature patterns, but also leading to higher frequency in extreme events and exacerbating pest and disease pressure on crops (Burdon and Zhan, 2020). Warmer temperatures may favor some crop pests; besides, they can react differently to precipitations, depending on their exact timing and amount (Skendzic et al., 2021). Climate change may also increase or decrease weed pressure and incidence, depending on many causes and different weed-crop species combinations (Shahzad et al., 2021). Ironically, some of the most important agriculture regions of the planet are threaten by water-scarcity problems, especially in future years, such as the arid southwestern USA (e.g., California's San Joaquin and Imperial-Coachella Valleys) or the Mediterranean region (e.g., Italy) (Abd-Elmabod et al., 2020; Corwin, 2020). In fact, California and Italy represent two key agricultural regions with globally significant production but are extremely vulnerable to the impacts of extreme climate events and for these reasons they have been considered as relevant geographical areas for this study. This mini-review discusses the climate change impacts on the agriculture sector of two different and very far geographical regions, California and Italy, which, however, share many climatic conditions and cultivated crop species ( Figure 1 ). The present study seeks to highlight how the adoption of agroecological principles, adapted as site-specific farming practices, represents the real alternative to ensure climatically resilient agricultural production in future decades.

California is one of the most important and diversified agricultural regions of the world (Petersen-Rockney, 2022a). Around 50% of the nuts (such as almonds, pistachios or walnuts) and fruits (including grapes, citrus, apricots, dates, figs, kiwi fruit, nectarines, prunes, and olives) consumed in the Unites States (US) are cultivated in California (Pathak et al., 2018). Considering the high relevance and economic value of these specialty crops and their specific environmental growth requirements, agricultural production in California is highly sensitive to climate change impacts.

The cumulative co-manifestation of dry and warm years in the “Golden State” increases the risk of drought stresses, highlighting the significant role of high temperatures in modifying water availability and overall drought impacts on agriculture sector (Mann and Gleick, 2015). For these reasons, California represents a valid case study to explore how agriculture sector is impacted but can also react to climate change and climatic extreme events, especially drought conditions (Petersen-Rockney, 2022b). Extreme weather events in the State, including more frequent heatwaves, heavy and extended drought conditions, floods are negatively impacting agriculture (Pathak et al., 2018; Weiskopf et al., 2020) and are estimated to increase in their intensity and frequency (IPCC, 2023). Analyzing California’s climate data over the past four decades, autumn precipitation has decreased by 30%, while temperatures have increased by about 1°C (Goss et al., 2020). Average temperature increases projections predict that higher temperatures will be more evident during the summer season than in the winter and there will be more warming in inland areas than in coastal regions (Pathak et al., 2018).

Regarding future precipitation scenarios, California will maintain its Mediterranean climate with moderately cold and wet winters and hot dry summers (Pathak et al., 2018). Different general circulation models forecast that Northern California may experience higher annual precipitation amounts and probably more frequent storm events, while the overall state and especially Southern California are projected to be 15 to 35% drier by 2100 (DWR, C.D.o.W.R, 2015). In fact, almost 80% of the California’s water in a typical year is provided by snow (Pathak et al., 2018). Provisional climate models suggest that 65% snowpack losses might occur by 2100, due to global warming (DWR, C.D.o.W.R, 2015). Generally, California’s climate is shifting toward a flood–drought pattern, also resulting in increased flood risks (Pathak et al., 2018).

Even if climate change globally impacts have been in-deep studied for main field crops, major impacts in California are related to “specialty crops”, defined by the United States Department of Agriculture (USDA) as all fruits (e.g. grape), nuts, vegetables (e.g. tomato), and nursery crops, which account for the highest economical production of Californian agriculture (Kerr et al., 2017). This unique relevance is possible because of California’s Mediterranean climate (exclusive in North America) and the large-scale supply systems for irrigation water. Grapes and tomatoes represent more than 20% of California “specialty crops” value (Kerr et al., 2017) and their importance for the agricultural sector could be considered similar also in the Italian agriculture.

The majority of specialty crops in California is irrigated, and around half of this irrigation is provided by groundwater (Cooley et al., 2015). Even if irrigation water could disguise the impacts on yields of climate change, potential evapotranspiration in California’s specialty crop growing regions will significantly increase, according to the future climate scenario (Kerr et al., 2017). Already for several years and more and more now, there are increasing concerns about whether California can continue to satisfy its massive water demand for industrial purposes, agriculture production, preserving ecosystems, and developing cities in the midst of drought (Christian-Smith et al., 2015).

Besides worsening pathogens or insect pests (Trumble and Butler, 2009; Jha et al., 2024) pressure on crops, driven by climate change, it’s estimated that, with a global warming trend of 3°C, weed species pressure in California and the central Midwest will substantially increase, for example considering itchgrass or witchweed (Anwar et al., 2021). Considering that the profitable value of specialty crops production is not simply related to yields but also to several quality characteristics (for example aesthetic features, shape, size or chemical composition), the majority of Californian agriculture production is particularly susceptible to climate change impacts (Pathak et al., 2018).

Mediterranean countries, such as Italy, have been recognized as climate change “hot spot”, since the incidence of high temperature extremes is estimated to increase by 200 to 500%, considering future greenhouse gas emissions scenarios (Nikolaou et al., 2020). The effect of climate change in Italy is increasingly perceived by citizens. In 2021, a Eurobarometer analysis highlighted that climate is the fourth concern for Italian citizens, following diseases, economy, and world hunger (De Leo et al., 2023). Similarly to California, drought is a raising challenge for Italy’s agricultural sector, causing a problem for the country’s major crops, as well as smaller farmers (OECD/FAO, 2021).

Average temperatures in the Mediterranean region are rising faster than the global average (Dari et al., 2023). Moreover, rainfall across the region is expected to decrease by 10% to 60% (Dari et al., 2023), exacerbating water scarcity issues, crucial for Italy’s water-intensive crops like rice and corn (Straffelini and Tarolli, 2023). Droughts, like those observed in recent years, have already caused significant yield reductions, while sudden storms and hail have damaged vineyards and olive groves, two pillars of Italian agriculture (Aguilera et al., 2020; Santos et al., 2020).

The largest decreases in productivity for Italy are expected for crops with a spring-summer cycle, especially if they are not irrigated, with yield reductions especially for corn, sunflower and sugar beet, while slight increases are expected for wheat (Hristov et al., 2020). Webber et al. (2018) reported that heat stress does not increase for corn and wheat crops under non-irrigated conditions, while water stress only intensifies for corn (with yield decreases in Italy around -20% values) and not for wheat (which instead shows stable yields or even increases of up to +20% in some areas of the country). Declines in rainfall directly impact crop yields. Corn, a major crop in northern Italy, relies on consistent irrigation, which is now threatened by shrinking water supplies from rivers like the Po river (Hristov et al., 2020). The projected raise in air temperature and changes in rainfall may cause a shortening ranging from 1.5 to 3 days in tomato phenology, triggering an overall 15% reduction in tomato yield (Cammarano et al., 2020).

Among tree corps, grapes, essential for Italy’s globally renowned wine sector, are highly sensitive to temperature changes. Some regions may need to adapt by shifting vineyards to higher altitudes or adopting heat-resistant varieties, in order to maintain production and quality standards (Droulia and Charalampopoulos, 2021). Olive trees, resilient to drought, are now facing challenges from rising temperatures and the proliferation of pests like the olive fruit fly, which thrives in warmer climates (Aguilera et al., 2020).

The economic levy of climate change on Italian agriculture is significant, with damages from extreme weather estimated at over €14 billion in the last decade (De Leo et al., 2023). Climate change disrupts rural livelihoods, reducing employment opportunities and exacerbating rural depopulation. Small-scale farmers, who dominate the Italian agricultural landscape, are particularly vulnerable due to limited resources for adaptation (De Leo et al., 2023).

Agroecology, integrating ecological principles into agricultural practices, offers a promising path to strengthen climate resilience by enhancing soil health, water efficiency, and ecosystem services (Altieri et al., 2015). Agroecology provides the best agricultural approach capable of coping with future challenges, by promoting high levels of diversity and resilience, while producing acceptable yields and ecosystem services (Altieri and Nicholls, 2020). Agroecology promotes the regeneration of the landscapes in which farming systems are present, improving the ecological networks, that may help in pathogens and pests prevention (Altieri and Nicholls, 2004).

California farmers will be challenged to adopt adaptation strategies in the future. In fact, California’s agriculture faces significant threats from climate change, particularly due to intensifying droughts and extreme weather events.

On the other side of the Atlantic Ocean, the vulnerability of Italian agroecosystems is a specific component of total changes affecting the Mediterranean basin, characterized by biodiversity loss, freshwater overemployment, disturbed nutrient cycles, soil losses and different fire patterns. This context is exacerbated in Italy by conditions of high population density, water scarcity, high dependence on material and energy imports, combined with the predominance of highly specialized and poorly diverse agroecosystems (Aguilera et al., 2020). Due to the need to create resilience to these connected risks, systemic adaptation measures are straightaway needed (OECD/FAO, 2021). Agroecology is based on an holistic vision, enabling the recovery and valorization of traditional knowledge and the co-creation of new local knowledge, for enhancing resilience (Aguilera et al., 2020).