Changes in vegetation phenology in spring, particularly the start of the growing season (SOS), are critical climate-induced changes (Piao et al., 2019;Richardson et al., 2013) that can alter the length of the vegetation growing season and influence the carbon, water, and energy fluxes between the terrestrial ecosystems and the atmosphere (

Transportation in the Pan-Arctic winter is highly dependent on ice roads, which are affected by surface air temperatures and snow cover. In the context of polar increased warming, there is an urgent need to quantify the uncertainties of ice roads and their contribution to terrestrial transport. We evaluated the spatiotemporal characteristics of potential ice road changes by calculating four indicators: potential ice road area (PIRA), potential ice road days (PIRDs), potential ice road onset date (PIROD), and potential ice road end date (PIRED) from October to May, 1979–2017. Taking port accessibility as an example, we constructed a port accessibility model to quantify the contribution of potential ice roads to terrestrial transport. All four indicators showed significant (p < 0.05) reductions in potential ice roads. PIRA experienced the largest share of losses in May (~25%) and the sharpest reductions in April (2.77 × 104 km2 yr−1). PIRDs were shortened by an average of 0.41 d yr−1, and delayed PIROD (0.28 d yr−1 on average) was more severe than advanced PIRED (0.21 d yr−1 on average). A stability analysis showed that potential ice roads were changing from suitable to unsuitable during November to May. Between December and April, potential ice roads can increase port accessibility by more than 24 h in Canadian Arctic and Siberia and by more than 9 h in Alaska. However, the contribution of potential ice roads has reduced over the past decades, especially in Nunavut. The results provide insights into changes in potential ice roads in the Pan-Arctic and suggest that remote land accessibility has decreased significantly with warmer winters.