The global burden of climate-sensitive health impacts: a systematic review of mortality, morbidity, and economic costs.

Rising greenhouse gas emissions are intensifying heatwaves, wildfires, extreme rainfall, and sea-level rise, reshaping global health outcomes. However, the full multisystem burden remains insufficiently synthesized. This systematic review quantifies global climate-sensitive health impacts, identifies vulnerable populations, and evaluates adaptation strategies. We searched seven databases and grey literature (2000-2025), including studies linking climate exposures to health outcomes. Dual screening, risk-of-bias assessment (ROBINS-I, ROB 2), meta-analysis, meta-regression, and GRADE certainty grading were applied. Sixty-five studies were included. Non-optimal temperatures were associated with 5.08 million annual deaths (2000-2019). Heat increased all-cause mortality by 3.3% per 1°C above local optimum, while compound heat-ozone events increased cardiovascular mortality by 5.7%. Wildfire smoke contributed to ~339,000 premature deaths annually and a 6% increase in myocardial infarction admissions per 10 µg/m3PM2.5. Climate-sensitive vectors may expose 1.3 billion people to Aedes-borne diseases by 2050. Heat-related labor losses reached 5.3% of global work hours (~US$671 billion in 2020). Climate-related anxiety/depression prevalence was 24%. Only 27% of World Health Organization (WHO) member States report fully funded health adaptation plans. Early warning systems and deep decarbonization could reduce mortality by up to 42% and avert >160,000 deaths annually. Evidence indicates disproportionate impacts in low-resource settings and multiple interacting pathways across physical and mental health, nutrition, and livelihoods. Climate change is already a major driver of global morbidity, mortality, and economic loss. Urgent mitigation and scaled, equity-focused adaptation are essential to reduce avoidable deaths and health inequities worldwide.