The Arctic polar stratosphere is becoming more similar to the Antarctic, where an ozone hole has been found. Chemical reactions in the Arctic polar vortex are causing ozone losses of 10 to 15% in certain areas, which could lead to 5 to 8% overall ozone depletion. With a 50% increase in stratospheric chlorine expected in the next 20 years, an ozone hole may develop in the Arctic as well.