Abstract: Global climate change is reshaping temperature and precipitation regimes, intensifying compound extremes and altering terrestrial ecosystem functioning. Although their individual effects on ecosystem productivity are widely studied, their joint variability, here termed temperature-precipitation (T-P) synchrony, has emerged as a critical but underexplored driver of ecological outcomes. Here, we synthesize current understanding of T-P synchrony and its impacts on ecosystem productivity. We use T-P synchrony as a cross-timescale umbrella concept encompassing three complementary, scale-dependent aspects: seasonal phase alignment, anomaly covariability, and long-term trend concordance. Anomaly covariability includes both relationships between anomaly time series and the co-occurrence of anomaly events. These aspects show pronounced spatial heterogeneity, with typical expressions ranging from different seasonal alignments to contrasting anomaly combinations and trend relationships. Recent studies report intensifying anomaly covariability, especially for compound extremes, whereas long-term trend concordance remains constrained by thermodynamic and hydrological limits. Together, these aspects of T-P synchrony help explain why similar warming can enhance productivity in some ecosystems but suppress it in others. In general, warm-wet conditions tend to enhance productivity, whereas warm-dry conditions often amplify drought stress, reduce carbon uptake, and increase mortality risk. These effects are filtered by ecosystem traits and mediated by hydroclimatic intermediaries such as vapor pressure deficit (VPD) and soil moisture. Future progress depends on clearer definitions, stronger linkage between T-P synchrony and ecological responses, and better mechanistic resolution in observations, experiments, and models. Such efforts should improve assessment of ecosystem productivity, carbon-sink stability, and vulnerability under continued climate change.

Key words: temperature-precipitation synchrony, ecosystem productivity, climate change, carbon cycling, water availability, compound extreme events