Ground-level ozone, the same pollutant that makes smog, is responsible for a surprisingly large part of the spring and summer warming that has been detected in the Arctic, NASA states in a new study. The pollution caused by highly industrialized countries at high latitudes is being blown northward, and resulting concentrations of ground-level ozone may be responsible for 30-50% of evident Arctic warming. The lesson is that industrial pollutants of all types threaten the global ecological system's balance.