## 1 Introduction  
Climate change is increasingly impacting our planet and its inhabitants. Increasing global land surface temperature is changing the precipitation patterns and heightening the frequency and severity of droughs, and as a result, it significantly affects the carbon and water cycles of terrestrial ecosystems [1, 2, 3]. Cropland is one of the most important terrestrial ecosystems, and it is both a victim of climate change and part of the solution. Climate change can exacerbate the soil evaporation, change the growing duration, and impact the yielding. Moreover, the extreme weather events such as droughs, floods, and heatwaves lead to crop failures and exacerbate soil erosion [4]. To address this global crisis, multifaceted measures are required, combing technological innovations, policy interventions, behavioral changes, and nature-based solutions. Terrestrial ecosystems adapt by altering their structural composition and modifying their sensitivity to climatic variations [5]. Reforestation and afforestation can enhance the sequestration of CO\({}_{2}\) and regulate water cycles. In addition, integrating trees with crops/livestock can enhance carbon storage and reduce soil erosion. Furthermore, precision farming, reduced tillage, and optimized fertilizer can be used to cut methane (CH\({}_{4}\)) and nitrous oxide (N\({}_{2}\)O) emissions. In developing effective mitigation strategies and sustaining life on our planet, it is especially important to understand the climatic controls on the biogeochemical processes of plants, particularly the carbon and water cycles [6]. Water use efficiency (WUE), serves as a vital physiological indicator for assessing variations in carbon and water fluxes [7, 8]. It plays an essential role in understanding plant resilience during drought conditions. A high WUE implies that plants minimize water loss by closing their stomata, thereby reducing evapotranspiration (ET) in response to drought. In contrast, a low WUE can indicate either adequate water availability or stunted plant growth [9]. WUE can be measured at various spatial scales, ranging from individual leaves to entire ecosystems, and across temporal scales from immediate readings to multi-year cycles [10]. Despite the availability of multiple definitions, the use of gross primary production (GPP) and ET for calculating ecosystem WUE has gained widespread acceptance in earlier research [6, 11, 12, 13]. Environmental variables, such as temperature (Temp), precipitation (PPT), carbon dioxide concentration (CO2), net radiation (Rn), vapor pressure deficit (VPD), soil volumetric water content (VSWC), and their interactions with biological factors (such as leaf area index (LAI) and enhanced vegetation index (EVI)) significantly influence seasonal variations in GPP and ET, leading to interannual fluctuations in WUE [14, 15, 16, 17, 18, 19]. Given the shifting climate and declining precipitation in the arid and semi-arid regions, there is growing research on examining the impacts of drought on terrestrial water and carbon cycles [9]. Ecosystems increase their WUE when shifting from wet to dry conditions and decrease it when transitioning from dry to wet [20]. Consequently, WUE has become a key metric for resilience analysis, helping to evaluate how terrestrial ecosystems react to hydroclimatic disturbance like drought [12]. Choosing drought-resilient species can enhance carbon sequestration, even during water-limited periods [6, 21]. Understanding the biophysical controls, especially that climate change on WUE requires comparative studies across various ecosystems and regions [11, 22]. Field measurement, such as eddy-covariance (EC) flux towers, allow for precise calculations of GPP and ET, thereby enabling accurate WUE assessments [23, 24, 25, 26, 27]. Nonetheless, ecosystems located in various geographical areas are expected to display distinct WUE patterns due to physiological variations and different environments [28, 29].