Forecasts by climate models suggest that summer sea ice will largely disappear in the second half of the century, but the current rate of ice loss exceeds the models' forecasts, suggesting that ice-free conditions could arrive sooner. With its thick piles of sedimentary rock, the Arctic may hold some of Earth's biggest hydrocarbon stores. The high price of oil is driving companies northwards, with drilling taking place or planned off the coast of Greenland and in the Kara, Barents and Chukchi seas.