Recent melt rates of Canadian arctic ice caps are the highest in four millennia

► There has been rapid acceleration in Canadian Arctic ice-cap melt rates since 1995. ► Melt series correlate well with Devon net mass balance. ► Last quarter century has seen the highest melt in two millennia. ► The Agassiz ice-cap melt over the last 25 years highest melt in 4200 years. ► The Agassiz melt rates since the middle 1990s resemble those 9000 years ago.