Why can tundra regions receive desert-like amounts of precipitation without becoming true deserts?

Tundra regions are not considered true deserts, despite receiving similarly low levels of annual precipitation, primarily because of the significant difference in evapotranspiration rates between the two environments.1

In hot and temperate deserts, high temperatures and low humidity lead to extremely high potential evaporation rates, which quickly deplete available moisture. In contrast, the cold temperatures of the tundra significantly reduce the rate of evaporation, allowing the limited moisture that does fall to remain available in the environment.123

Furthermore, the presence of permafrost in the Arctic tundra acts as an impermeable barrier that prevents water from draining downward through the soil. This causes the ground to become saturated and boggy during the summer thaw, providing sufficient moisture to support a continuous cover of vegetation—such as mosses, lichens, grasses, and shrubs—which distinguishes the tundra from the sparse, barren landscapes typical of true deserts.241