## 3 Results and Discussion
#### 3.2.2 Relationships between Daily Air Temperature and CO\({}_{2}\) Flux Anomalies  
The response of CO\({}_{2}\) fluxes to extreme temperatures varied significantly between ecosystems and even within one biome. It may have been due to the stronger dependence of CO\({}_{2}\) fluxes of tropical ecosystems on the precipitation than on temperature variations, as was evidenced by the earlier analysis of the time series. At two savanna stations (AU-Dry and AU-RDF), the extreme high temperatures resulted in increased CO\({}_{2}\) emissions (Figure 3a) and extreme low temperatures--in increased CO\({}_{2}\) uptake (Figure 3c). The inverse relationship was also significant (with lower percentage): the positive CO\({}_{2}\) flux anomalies were more likely during the hot days (Figure 5a) and negative anomalies--during the days with temperature declines (Figure 5c). At the station AU-Ade, the opposite response was detected: minimum temperatures were associated with increased CO\({}_{2}\) emission (up to 38% of the days) and maximum temperatures, in turn, with CO\({}_{2}\) uptake (up to 30% of the days). In Sahel (SN-Dhr), the hot days were characterized by prevailing increased CO\({}_{2}\) uptake. In Congo (CG-Tch), there was no evident relationship between air temperature and CO\({}_{2}\) flux variations, which was likely the result of the dominant influence of precipitation conditions (as evidenced by the high percentage of precipitation extremes). At least in Sudan (SD-Dem), the negative CO\({}_{2}\) flux anomalies dominated during the period of observations, with no relevance to the temperature changes. In the evergreen forests, the temperature decreases mainly coincided with high CO\({}_{2}\) emissions (Figure 4c). Similar relationships were found in seasonal or dry forests (an exclusion for MKL, where the positive and negative CO\({}_{2}\) flux anomalies were equally likely during the periods of low temperature) and in wetlands (Figure 3c). However, these tendencies may also have been related to precipitation changes: as mentioned above, the abundant precipitation results in increased net CO\({}_{2}\) releases due to lower GPP and higher ER. At the same time, the heavy precipitation was accompanied by increased cloudiness. Cumulonimbus clouds with a high cloud optical depth dominated in the equatorial latitudes. This led to a significant reduction in total solar radiation, a corresponding decrease in temperature under cloudy conditions, and a large angle of incidence of sunlight. However, in Australian evergreen and tropical rain forests, the positive CO\({}_{2}\) flux anomalies occurred, on the contrary, during the days with high temperature (Figure 4a) and negative CO\({}_{2}\) flux anomalies--during the days with low temperature (Figure 4c). In comparison to precipitation, when the maximum percentage of simultaneous extremes in weather conditions and CO\({}_{2}\) fluxes was observed for the 95% quantile threshold, for temperature, the maximum percentage was observed for the 90% quantile of PDF. 2.3 The Correlation between Daily CO\({}_{2}\) Flux Anomalies and Temperature/Precipitation Extremes  
The correlations between extreme air temperature (precipitation) and CO\({}_{2}\) flux anomalies confirmed the results mentioned above (Table 1). Correlations were calculated for the time series, consisting of the days when the extreme event threshold was exceeded: 5%/95% (P Q95) and 10%/90% (P Q90) quantiles for precipitation and 5%/95% (T Q95) and 10%/90% (T Q90) quantiles with \(\pm\)1 STD (T STD) for temperature. The number of samples used for correlation analysis is shown in Table S1 of the Supplementary Materials. The extreme precipitation was positively correlated with CO\({}_{2}\) flux anomalies, i.e., the abundant precipitation was associated with the strong CO\({}_{2}\) release and weak precipitation with increased CO\({}_{2}\) uptake.