The North Atlantic oscillation is an atmospheric phenomenon affecting the weather in Western Europe. When the atmospheric pressure variations in the North Atlantic are large, the springs in Europe are warmer. This brings forward the northward migration of those bird species (including the goldcrest) that winter mainly within western or southern Europe. A general climatic change resulting in more frequent positive North Atlantic oscillation events has led to earlier spring migration of these short-distance migrants since the 1980s. The warmer spring weather brings on plant growth, thus preparing the habitat for returning migrants. The effect is greatest in western and central Europe.