Mountain glaciers face centuries-long recovery even if warming is reversed. Overshooting 1.5C, even temporarily, locks in glacier loss for centuries. Much of this damage cannot simply be undone–even if temperatures later return to safer levels. Melting glaciers will significantly affect downstream water supplies.
www.spacedaily.com/reports/Mountain_Glaciers_Face_Centuries_Long_Recovery_Even_if_Warming_Reversed_999.html