How does global warming cause changes to our normal 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 very fast
The warming in the Arctic is happening about 2-3 times faster than 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 is 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 norther regions are changing very fast.
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 very rare before about 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.