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How does global warming change our weather patterns?

rossby waves in the jet stream

Climate change and global warming are indeed changing weather patterns across the world. Dry areas get more rain, wet areas get less rain, and storm systems are much stronger. The reason global warming changes weather patterns is complex but clearly understood by scientists. Here’s how climate change impacts our weather patterns.

The jet stream drives weather patterns

The jet stream is a strong wind current flowing about 10 miles above the ground. In the Northern Hemisphere, it almost always blows from west to east and always in a fairly straight line. The jet stream is extremely important to weather systems – it drives the weather patterns throughout the year. The strength of the jet stream, and to what degree it impacts our weather, is determined by the temperature difference between the Arctic and the southern half of the world.

CO2 causes temperatures to rise

The level of CO2 in our atmosphere has been measured atop the Mauna Loa volcano in Hawaii since around 1958. At the time measurements began, the CO2 measured 315 parts per million (ppm). Today it measures at 415 ppm. The measure drops slightly in the summer because plants grow and absorb carbon dioxide. Then it begins climbing in the Fall until it peaks around April the following Spring. The high levels of CO2 are causing temperatures to rise around the planet.

Northern temperatures are rising extremely fast

The warming in the Arctic is happening about 2-3 times faster than in other areas of the world. The permafrost (frozen soil) is thawing and releasing more greenhouse gases (methane, carbon dioxide) as it melts. The sea ice covers only half the area it used to cover so sunlight is not being reflected back into space and instead is absorbed by the water which warms and releases even more CO2. The temperatures in northern regions are changing very fast.

Those pesky Rossby waves

Now that CO2 in the atmosphere is so high and the polar region is much warmer, it has thrown off the jet stream which is now moving erratically north and south. Instead of a Straight-line flow of air, it is now wavy, something the weather guys call “Rossby waves”.

Rossby waves were exceedingly rare before 1999. Now they occur frequently. When Rossby waves are present, weather systems do not move through the air very fast and instead, tend to float around in one place (or meander along just like the Rossby waves). When weather systems float around in one place, heatwaves become more severe, and storms tend to sit in one place for a longer period of time.

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