If you’re living somewhere in the middle latitudes, you might be experiencing suddenly colder than normal weather at times. Some around you maybe prompted to ask, “So where’s the global warming we’ve been hearing about?” Of course, you are probably aware of the differences between climate and weather, weather being a more short-term experience, which can include considerable volatility. Climate is the long-term picture.
However, a longer-term pattern of suddenly colder and then suddenly warmer weather in the middle latitudes, according to climate scientists, is likely an effect of general global warming. Here’s why.
Global warming is causing the polar regions to warm twice as fast as the middle latitudes. This is due to the fact that ocean ice in the artic is being reduced quite rapidly. Thus, the reflective white surface is being replaced by the dark ocean surface, which causes more heat to be absorbed, and yet more ice to melt, and warming to accelerate in the arctic from this feedback loop.
This accelerated warming in the arctic is causing a reduction in the temperature gradient, the contrast between the temperatures of polar regions and those of the middle latitudes being reduced. This reduction in temperature gradient affects the jet stream, weakening it, reducing its speed, and causing it to dip more north and south rather than remaining a mostly west-east direction.
This dipping can bring colder air down from the arctic or bring unusually warm air up from southern regions. So, for example, the beginning of December could be colder than normal with a sudden change later in the month to much warmer than normal. Once in a while this happens within the normal climate ranges, but the pattern seems to be repeating more than normal, probably as a result of global warming that especially affects the polar regions. So watch the rest of the winter in the middle latitudes. What will January, February, and March be like? You might be able to detect this global warming effect.