The recent invasion of Arctic air across the central and eastern U.S. was the latest event to embolden those who, for whatever reason, are committed to debunking the evidence of global warming. However, temporary weather patterns are generally unrelated to climate though climate change might fuel an increased incidence of such events..
Indeed, this Arctic blast resulted from a deep dip in the jet stream (known as an atmospheric trough), which allowed polar air to spill southward. As often occurs with extreme gyrations in the jet, other areas, including northern Europe and Asia, have been warmer than usual, reflecting a northward shift of the jet stream (known as an atmospheric ridge). The western U.S., not affected by the recent Arctic fronts, has also been warmer and drier than usual, exacerbating drought in the mountains of California.
The climate of any given region is determined by latitude, elevation, the proximity to large bodies of water or mountain ranges and the local effects of ocean currents, among other factors; all of these combine to produce average seasonal temperatures and precipitation for that region. While temporary weather patterns may obscure those averages, changes in climate are gradual, developing in response to alterations in solar radiation, the composition of the atmosphere and ocean currents; the latter currents generally change in response to plate tectonics and continental drift. Despite the recent Arctic air invasion, there is a wealth of scientific evidence that Earth's climate is warming and that human activity is playing a significant role.
