Extended Gap Between Snowmelt and Greenup Increases Dust Storm Occurrence.

Impacts of climate change on spring phenology and snowmelt timing are well-documented across the Northern Hemisphere. However, the critical period between the snowmelt end date (SED) and the start of the growing season (SOS)-the SED-SOS gap-and its consequences have been largely overlooked. Here, we use satellite-derived and ground-based SED and SOS data from 2001 to 2019 to investigate temporal trends in the SED-SOS gap and the potential impacts across the Northern Hemisphere. We find that SED-SOS gap has extended at an average rate of -0.10 days yr-1, with approximately 50% of the regions exhibit an extending trend. In high-latitude and high-altitude regions, the SED-SOS gap tends to narrow due to delayed SED or a faster advancement of SOS than that of SED, while mid-latitude regions show extending gaps due to faster SED advancement or delayed SOS. A case study in Inner Mongolia reveals that an extended SED-SOS gap significantly increases dust storm occurrence by enhancing soil exposure to wind erosion, posing potential threats to ecosystems and human health. As SED and SOS dynamics become increasingly complex under future climate change, our findings emphasize the importance of monitoring the SED-SOS gap and understanding its dynamics to inform climate adaptation strategies and protect ecological and societal well-being.