Societies and ecosystems that reside within and downstream of mountains rely on seasonal snowmelt to satisfy their water demands. Anthropogenic climate change continues to reduce mountain snowpacks worldwide, altering snowpack persistence and snowmelt magnitude and timing. Here, the global warming level leading to deleterious, widespread and persistent mountain snowpack loss, termed low-to-no snow, is estimated for the world's most latitudinally contiguous mountain range, the American Cordillera. These estimates are derived from a recent high-resolution Earth system model ensemble (HighResMIP), that assumes a high-emissions scenario, and uses atmospheric model intercomparison project (AMIP) protocols. We show a combination of dynamical, thermodynamical, and hypsometric factors give rise to an asymmetric emergence of low-to-no snow conditions within the midlatitudes of the American Cordillera. Low-to-no snow emergence occurs approximately 20 years earlier in the Southern Hemisphere, at a third of the local warming level, and coincides with runoff efficiency declines (average of 8%) in both dry and wet years. Prevention of a low-to-no snow future in either hemisphere requires the level of global warming to be held to, at most, +2.5 °C.