Different Response of СО2 and Н2О Fluxes to the Anomalous Weather Conditions in Tropical, Temperate and Polar Latitudes

The effects of extreme temperatures and precipitation on the variability of CO2 and H2O fluxes in ecosystems across tropical, temperate, and polar regions during the warm season were investigated using ERA5 reanalysis data and data from the global FLUXNET and regional AmeriFlux networks. The study revealed that extremely high temperatures and heavy precipitation represent the most unfavorable conditions for plant community productivity in temperate and polar regions across all studied ecosystems. These conditions are accompanied by enhanced CO2 emissions to the atmosphere, largely driven by increased ecosystem respiration. Elevated temperatures weaken assimilatory processes and reduce primary production. Heavy precipitation exerts the strongest impact on CO2 fluxes by accelerating the decomposition of soil organic matter, increasing autotrophic and soil respiration, and consequently enhancing CO2 emissions. In the tropics, a similar response was observed with increased CO2 emissions across most biomes except savannas. This response is driven by the same processes as in extratropical regions. However, the response of CO2 fluxes to abnormally high temperatures differs in the tropics compared to temperate latitudes. In tropical ecosystems, enhanced CO2 uptake occurs during hot periods because anomalously high temperatures are not a limiting factor for plant growth under sufficient soil moisture conditions. The response of CO2 fluxes to low temperatures is more complex and varies even within the same biome, a pattern characteristic of all latitudinal zones. The key distinction in ecosystem responses to weather extremes is the dominant influence of temperature anomalies in temperate and polar regions, while precipitation extremes have a stronger influence in tropical regions. The response of water vapor fluxes to extreme temperatures is generally similar across latitudinal zones: evaporation increases with high temperatures and decreases with low temperatures. However, the response to extremely heavy precipitation differs between tropical and extratropical regions. In tropical regions, intense precipitation enhances evaporation. In temperate and polar regions, however, heavy precipitation reduces evaporation.