Diverging Spring Warming and Growing Season Shifts Across Eurasia and North America Under Future Climate

Abstract Springtime warming over Northern Mid‐High‐latitude Land profoundly affects plant life cycles and water resources, yet large model uncertainty limits climate risk assessment. Here, we develop a novel emergent constraint that targets the key uncertainty source—model divergence in surface‐albedo feedback linked to historical snowmelt sensitivity. This approach halves the spread of projected warming and reveals a pronounced geographical asymmetry. Under the high‐emission scenario (SSP5‐8.5), current climate models underestimate end‐of‐century warming over Eurasia by 0.80°C but overestimate it over North America by 0.44°C. These refined projections substantially alter ecological outcomes: the start of the growing season is predicted to advance by about 18 days in Eurasia and 8 days in North America, representing a 3‐day greater advance and 1‐day delay compared with original estimates. Our findings offer a more reliable basis for assessing climate change impacts on ecosystems and water resources and highlight the urgency of region‐specific adaptation strategies.