## 3 Results
### Climate Conditions for CUE Extremes  
There were no significant correlations between CUE and climatic factors in most areas of the globe. Temperature played a negative role in CUE in some areas of the globe (Figure 7). In MAM and DJF, the correlations of CUE and temperature were negative, with the partial correlation coefficient being smaller than \(-\)0.4 in some regions of Southern America. In JJA, the partial correlations between CUE and temperature were smaller than \(-\)0.6 in the Northern Hemisphere at high latitudes. The partial correlations between CUE and precipitation were positive in some areas of high latitude in the Northern Hemisphere at JJA, with the partial correlation coefficients larger than 0.4. Additionally, there were no significant correlations in MAM, SON, and DJF. There were no significant correlations between CUE and solar radiations during the four seasons in the global. Thus, we chose temperature and precipitation to analyze the climate conditions of CUE extreme events. There were opposite temperature anomalies in positive and negative CUE extreme events (Figure 8). Overall, the negative CUE extreme events are often accompanied by positive temperature anomalies, and positive CUE extreme events are attended by negative temperature anomalies in the four seasons. In MAM (Figure 8a), the average temperature anomalies in positive CUE extremes regions ranged from \(-\)0.8 \({}^{\circ}\)C to 0 \({}^{\circ}\)C at different latitudes. Conversely, in most latitude regions, the average temperature anomalies in negative CUE extreme areas ranged from 0 \({}^{\circ}\)C to 0.8 \({}^{\circ}\)C at different latitudes. In JJA (Figure 8b), the average temperature anomalies were larger than zero in negative CUE extremes and smaller than zero in positive CUE extremes. In particular, at northern middle-high latitudes (>40\({}^{\circ}\)N), the temperature anomalies were larger than 1 \({}^{\circ}\)C in negative CUE extremes and smaller than \(-\)1 \({}^{\circ}\)C in positive CUE extremes. In SON (Figure 8c), the average temperature anomalies ranged from \(-\)0.5 to 0 \({}^{\circ}\)C in positive extremes and 0 to 0.5 \({}^{\circ}\)C in negative CUE extremes. In DJF (Figure 8d), there were more obvious temperature anomalies in the Southern Hemisphere than in the Northern Hemisphere, and the average temperature anomalies ranged from \(-\)0.5 to 0.5 \({}^{\circ}\)C in CUE extremes. These results suggest that warming is harmful to promoting carbon absorption in global terrestrial ecosystems. Figure 6: Spatial distribution of the probabilities of concurrence positive extremes of CUE with (**a**) positive extremes of GPP and (**b**) negative extremes of Ra. Negative CUE extremes with (**c**) negative extremes of GPP and (**d**) positive extremes of Ra. Figure 8: The averaged (**a**-**d**) temperature and (**e**-**h**) precipitation anomalies in positive (green line) and negative (red line) CUE extremes pixels at different latitudes in the four seasons. “MAM” contains the month of March, April, and May; “JJA” contains the month of June, July, and August; “SON” contains the month of September, October, and November; “DJF” contains the month of December, January, and February. Figure 7: Spatial pattern of the partial correlation coefficients between CUE and TAVG, PRCP, and RAD in (**a**-**c**) MAM, (**d**-**f**) JJA, (**g**-**i**) SON, and (**j**-**i**) DJF. Shown are significant correlations (\(p<0.01\)). “MAM” contains the month of March, April, and May; “JJA” contains the month of June, July, and August; “SON” contains the month of September, October, and November; “DJF” contains the month of December, January, and February. Precipitation had opposite performances to temperature in CUE extremes. Positive precipitation anomalies accompany positive CUE, and negative precipitation anomalies attend negative CUE. In MAM (Figure 8e), the precipitation anomalies ranged from 0 to 20 mm in positive CUE extremes and from \(-\)20 to 0 mm in the negative CUE extremes.