Abstract
Climate change is increasingly reshaping the environmental conditions under which global food systems operate, posing critical challenges to crop productivity and agricultural stability. While previous research has largely focused on correlating climatic variables with yield outcomes, less attention has been given to the physiological mechanisms through which climate stressors translate into productivity losses. This study adopts a global, physiology-informed analytical framework to examine how rising temperatures, altered precipitation regimes, and increasing atmospheric CO₂ concentrations interact to influence plant functioning and crop yield dynamics. Using a multi-dimensional panel dataset representing major staple crops across diverse agroecological zones from 1990 to 2024, we integrate climatic drivers with physiological stress proxies, including stomatal conductance, canopy vigor, vapor pressure deficit, and composite heat–drought indices. A suite of nonlinear statistical analyses and specialized visualizations was employed to capture threshold behavior, compound stress effects, and yield volatility. The results reveal that crop responses to climate change are highly asymmetric and governed by physiological tipping points rather than gradual exposure–response relationships. Heat and drought stress act synergistically to suppress photosynthetic efficiency, destabilize reproductive processes, and accelerate senescence, leading to disproportionate yield losses once tolerance limits are exceeded. Although elevated CO₂ exerts a modest fertilization effect, this benefit is insufficient to counteract the negative impacts of thermal and hydric extremes. Yield anomaly distributions further indicate that climate change is increasing the volatility of agricultural systems, with extreme negative outcomes occurring more frequently than positive gains. These findings demonstrate that climate change affects crop productivity primarily through internal physiological constraints rather than direct climatic exposure alone. Accordingly, adaptation strategies must prioritize the enhancement of physiological resilience particularly heat tolerance, hydraulic stability, and reproductive robustness—over short-term yield optimization. This study contributes a mechanistic perspective to global climate–crop assessments, offering a biologically grounded foundation for more accurate projections of future food security under intensifying climate stress.