During the last week of January 2019, the eastern half of the United States was gripped by an incredible cold spell where temperatures in Chicago, for example, dipped below temperatures in certain parts of the Arctic. The cause of this weather event is the Polar Vortex. Many first heard of the polar vortex in January 2014 where temperatures in some locations of the US dipped to life-threatening lows. The polar vortex is not a new phenomenon or a fancy term used by meteorologists. Scientists have known about it for a long time. What is the Polar Vortex and how is it related to climate change and global warming, which the White House likes to deny and characterize as a “hoax” and the Democratic Party fails repeatedly to sufficiently address?
Winds are driven by the difference of pressure that exists between different regions on Earth’s surface (horizontally) and aloft (vertically). The larger the pressure difference the stronger the wind. One might ask: what is pressure and why and how does it change?
Pressure is a measure of the mass or weight of air above a given area. As we climb in elevation above the Earth’s surface, there are fewer air molecules above and therefore the atmospheric pressure is lower than at lower elevation. Atmospheric pressure is also related to temperature. As temperature rises, air expands and conversely, when temperature falls, air shrinks. Now imagine that we have two areas – one with cold air above it and the other with warm air. Also assume that the two masses of air are contained by some invisible membrane which prevents the mixing of the two masses of air. The height of the column of air over the warm area is higher than that over the cold area. Consequently, as we climb in elevation above the warm area, there are more air molecules above us than at the same elevation over the cold area. This means that warm air aloft is associated with high pressure and cold air aloft is associated with low pressure. As a result, a horizontal difference of pressure exists between the two areas. If we now remove our imaginary container that prevented the two masses of air from mixing air from high pressure moves to low pressure in an attempt to equalize the air pressure. This differential pressure is the force that drives winds. As the pressure difference increases so does the wind speed.
Another force that affects the air motion—or any other free-moving object—on Earth is what is known as the Coriolis force, which is due to the earth rotation. This force causes any free-moving object to deflect from a straight line trajectory. In the Northern Hemisphere, the Coriolis force causes the wind to deflect to the right of its path and to the left of its path in the Southern Hemisphere.
Aloft at the boundary of the cold air over the Polar Regions (North and South) and milder air over the middle latitudes, a sharp contrast in temperature exists resulting in a steep difference of pressure which intensifies the wind speed along this front and causes what is known as the “jet stream” situated about 10km to 15km (30,000ft to 60,000ft) above the surface. The jet stream is like a river of wind that flows from west to east and circles the polar region confining the cold air over the poles. During winter the winds within the jet stream are strong and often reach speeds over 100knots. Dragged by the winds of the jet stream, the mass of cold air over the Polar Regions also circulates in a counter clockwise direction and is referred to as the polar vortex. So the jet stream plays an important role by keeping the cold polar air confined to the Polar Regions. It is important to note that the jet stream shape is not regular. It tends to meander and could extend away from the poles into the middle latitudes (troughs) or recedes where warmer air extends toward the poles (ridges). During summer the jet stream is weaker due to the decrease of the temperature difference between the Polar Regions and mid latitudes.
In recent years measurements taken have shown that more and more ice in the Arctic is melting during the summer months, resulting in the warming of the Arctic Ocean. In winter this heat is radiated back to the atmosphere and results in warming the air over the Arctic which results in lower difference of temperature between the Arctic and the middle latitudes. Consequently the wind speed within the jet stream becomes weaker and its shape becomes more irregular as certain areas over the arctic experience more or less warming. As the wind speeds within the jet stream weaken, the polar vortex extends further away from the Arctic into the middle latitudes as the confining ability of the jet stream is lessened.
As the temperatures dipped to dangerous levels, global warming skeptics pointed out the apparent contradiction. How could the earth be warming when we are experiencing such extreme cold? Such claims show a serious misunderstanding of what “global warming” means. It does not mean that every region on Earth sees warmer temperatures in all seasons. It means that the average air temperature integrated over the whole planet is rising. Some regions may experience colder temperatures while others may experience warmer temperatures. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century. As the global average temperature rises, polar ice melts and more of the Arctic Ocean water is exposed to warming resulting in a weaker and more irregular jet stream and polar vortex potentially causing more frequent cold snaps. The contradiction is only in appearance as the polar vortex irregularity is the result of the rise of average temperature over the Arctic and the rest of the globe. The tweet of Trump also shows an ignorance of the difference between climate and weather. Weather denotes the conditions of the atmosphere at a given point of time and a given location. Climate, on the other hand represents the accumulated daily and seasonal weather events over a long period of time.
Global warming affects every aspect of life on earth: more expensive food, drought and water shortages, more severe and frequent weather events, less fertile soil, extinction of species, etc… However, the impacts of climate change will disproportionately be felt by the poor, the middle class, peasant farmers and generally ordinary working people. This means that global warming and climate change are not only scientific issues but are class issues as well. Scientists have been sounding warnings about global warming and environmental destruction for decades. The lack of serious effort in reversing the trend of rising global temperature clearly demonstrates the inability and unwillingness of the capitalist economic system to resolve the contradictions that accumulation and commodification engender. Actions to counter global warming the climate change cannot be left to the whims of the free-market and the capitalist class. Only an economic system controlled and owned by the workers and which aims at satisfying the needs of people rather than the maximization of profits and the commodification of labor and nature will be capable of providing and creating a healthy and sustainable environment.