How can global warming produce more extreme winter storms? Or extreme cold spells? Why are the climate scientists concerned that civilization might collapse?
This essay explains these dynamics. I begin with a simple analogy.
Consider a large pot of cold water sitting on a heater. The initial state of the cold water is stable. The water is just sitting there. There are no currents, no movement of the water. The temperature is the same at every point within the pot.
Now turn the heater on low. The water begins to heat and gradually a temperature gradient develops. The temperature gradually increases at the bottom of the pot.
As the temperature on the bottom increases, eventually a local instability develops and a hotter blob of water will suddenly begin rising while some colder water will sink. The pot of water now enters a chaotic state … seemingly random blobs of hot water suddenly rise and cold blobs sink.
If the heater is turned up more, the pot will rather suddenly develop a much more stable structure: a convection current in which the hotter water rises in the middle and the cooler water sinks along the sides of the pot. Continuing to turn up the heat results in the convention current speeding up. This stable structure endures until another critical transition point is reached and the water begins to boil.
Boiling initially involves a few gas bubbles forming in the center at the very bottom. More heat generates more and bigger bubbles and eventually the pot is at a full, rolling boil. At this point the pot has two kinds of structure: The rather stable convection current continues to rise in the center and fall along the edges. The second structure involves a chaotic formation of gas bubbles at the bottom of the pot. These bubbles rise to the top and escape as steam.
There are a couple of crucial lessons I want to draw from this simple example.
- The pot of water goes through several different states as the heat input increases:
- Uniform temperature throughout, no currents, no movement
- Small temperature gradient, chaotic currents
- Large temperature gradient, stable convection currents, no boiling
- Rolling boil, high heat, stable convection currents AND chaotic formation of gas bubbles.
- The transition from one state to another is relatively sudden and difficult to predict (unless the system in question is thoroughly understood).
How does all this apply to planet earth?
Our atmosphere and our oceans are fluids that obey the same laws of fluid dynamics that govern the behavior of the pot of water. Instead of a heater, the planet has the sun. More importantly, greenhouse gases are trapping an increasing amount of the sun’s heat, thereby in effect turning up the heater under the pot. Because of humankind’s activities, we are “turning up the heat” under our planet.
Our climate, for any given region, is determined by a combination of what goes on in the atmosphere and the oceans. The oceans absorb heat from the sun and the atmosphere and redistribute that heat all around the world via the ocean currents. The jet stream, relatively narrow bands of wind often exceeding 250 miles per hour at an altitude of around 8 miles, is also critical in determining climate patterns.
Of course the actual behavior of the oceans and the atmosphere is enormously more complicated than the currents in a simple pot of water. Nevertheless, there are important conclusions we can draw from our analogy.
- The stable currents in the atmosphere and the oceans almost certainly are capable of quite different states from those we observe today. For instance, the jet stream has historically been rather stable in its path. The path followed by the jet stream has become erratic in the last couple of years.
- A transition in the atmospheric or oceanic currents might be rather sudden.
The increasingly extreme weather of the last couple of years seems to be caused by the erratic behavior of the jet stream which, e.g., can cause artic air masses to move further south than normal.
The other reason to expect more extreme weather is simply that more heat causes faster currents. Just as more heat speeds up the currents in a pot of water, similarly more heat will speed up everything in the atmosphere and the oceans.
The second of our lessons is that transitions might be rather sudden. “Rather sudden” in the context of global weather patterns probably means a time scale of a year or so. If, e.g., some of the major ocean currents were to change, the weather the following year would almost certainly be quite different. Similarly, changes in the jet stream cause changes in regional weather patterns within a year.
Why should we be concerned about this? What’s the big deal about a little more extreme weather? Why not just buy a warmer coat and a little bigger air conditioner?
The scientific consensus today is that we have “locked in” at least a four degree Fahrenheit increase in the global temperature. What this means is that even if we stopped putting greenhouse gases into the atmosphere, the global temperature would still rise by at least four degrees by the end of the century. And of course, humankind is still increasing the amount of greenhouse gases we pump into the atmosphere each year. This means that our children and grandchildren are certain to have a world that is at least four degrees warmer than it is today and, if we don’t stop increasing the greenhouse gases, the increase will be considerably more than four degrees.
What are the major implications of a four degree rise in temperature? The Intergovernmental Panel on Climate Change says the global temperature has increased 1.53 degrees since 1880. While four degrees does not sound like much, it is actually huge.
- A four degree change in temperature within a century is unprecedented in the entire history of life on earth. Most species of plants and animals are unable to cope with a change this rapid. We are already in the midst of the greatest species extinction event in the history of planet earth. Given that we humans are dependent on this web of life, this will effect us in multiple and unpredictable ways, especially since we sit at the top of the food chain and are therefore vulnerable to the changes that begin low in the food chain and then ripple throughout. Already we saw vast swarms of jellyfish where before we had fish for eating and as suddenly as they came, the jellyfish now seem to have disappeared.
- Farmers are utterly dependent on stable weather patterns. What crops to plant, when to plant them, and when to harvest them … all of this depends upon weather patterns that are stable and predictable. Already regions of Africa that were self-sufficient in food are suffering famines because the timing of the rains became erratic. As the global temperature continues to climb, we can expect this problem to become worse and to increasingly impact more regions. Since we are barely managing to feed the world now, widespread disruptions to farming will likely lead to mass starvation.
- Glaciers are disappearing all over the world. Vast regions of Asia and India, as well as California and most of the USA Southwest, are watered by snowfall and glacial melt in high mountains. As these glaciers disappear, the water for irrigation also disappears. This is another major threat to the world food supply.
- Greenland and Antartica are covered in miles deep ice fields. If these two were to melt entirely, sea level would rise by about 200 feet. Think about that … that is about twice as high as the tallest oak trees. Every coastal city on the planet would be inundated by a sea-level rise of 200 feet. A recent study in the journal Environment and Urbanization found that a sea-level rise of 33 feet would threaten 634 million people. No one knows what is going to happen to the ice fields in either Greenland or Antartica, but we do know that melting in both areas has substantially accelerated in recent years. Rising global temperatures will, at some unknown point, cause both Greenland and Antartica to melt entirely. Rising sea levels thus threaten to cause the biggest mass exodus in human history. Eight years after Hurricane Katrina, New Orleans continues to struggle with reconstruction. Is it conceivable that we in the USA could relocate all of our coastal cities in a time span of 50 or even a hundred years? And the task is even more daunting for poorer countries.
Four degrees increase in global temperature threatens us with mass extinctions and radical ecosystem changes, failing crops and mass starvation, and the biggest forced exodus in human history.
Are we humans able to deal with challenges on this scale? Will we continue business as usual, like lemmings racing off the cliff, until our technology disintegrates and the survivors revert to a life style similar to George Washington’s in 1776?
Almost 40 years ago Kenneth Boulding, after cataloging the challenges facing us, said “An ill-founded optimism is still to be preferred to a well-founded despair.”
It seems to me that Boulding’s conclusion is still appropriate … but our time grows dangerously short indeed.
Let us come together in action so that our children and grandchildren inherit a world of plenty rather than a ravaged wasteland.
Contact me: I love to hear from readers. Email me at cyberneticapress at gmail dot com. Thanks, Barry Clemson