Environmental Change Is Reshaping the Temperature Sensitivity of Sesquiterpene Emissions and Their Atmospheric Impacts.

Air temperature is a critical regulator of ecosystem functions, including the release of biogenic volatile organic compounds (BVOCs) that mediate biosphere-atmosphere interactions. Among these, sesquiterpenes (SQTs) stand out for their dual role as ecologically significant compounds and highly reactive atmospheric constituents. Despite the inherently complex relationship between temperature and biogenic emissions, global emission estimates rely on simplistic parameterizations, assuming a fixed exponential response across all ecosystems and environmental conditions. Here, we synthesize two decades (1997-2019) of SQT emission studies, uncovering significant variability in temperature responses and basal emission rates driven by plant functional types (PFTs) and diverse environmental co-factors. When PFT-dependent parameterizations are integrated into emission-chemistry simulations, the results reveal sensitive feedbacks on atmospheric processes, including ground-level ozone (O) production and secondary organic aerosol (SOA) formation. Surprisingly, we identify a statistically significant decline in SQT temperature responses over time, suggesting that evolving environmental changes are reshaping the fundamental relationship between temperature and SQT emissions. This meta-analysis highlights the temperature sensitivity of sesquiterpenes (β) as a key parameter at the interface of the biosphere, abiotic and biotic environmental change, and atmospheric processes, with cascading effects on air quality and climate. Our findings emphasize the potential to consider β as a "volatile stressometer" for ecosystem-atmosphere interactions, where environmental stresses regulate the emission responses, with cascading effects on atmospheric chemistry and wider implications for future climate-vegetation feedbacks.