Atmospheric researchers have now developed a climate model that accurately depicts the winding course of the jet stream, the powerful band of westerly winds over the middle latitudes, which push major weather systems from west to east. Sea-ice retreat & the accompanying increased activity of atmospheric waves are creating a significant, ozone-amplified warming of the polar stratosphere. Since the low polar temperatures form the jet stream's motor, the rising temperatures in the stratosphere are causing it to falter. In turn, this weakening of the jet stream is now spreading downward from the stratosphere, producing weather extremes. This new combo-model now shows that the jet stream's wavelike course in winter & subsequent extreme weather conditions cold air outbreaks in Central Europe and North America are the direct result of climate change.'