I believe that most thoughtful people, studying all sides, would conclude that global warming represents a real threat to the human species. Part of that threat is well known, but the potential long-term effects are multi-fold, and all aspects need to be discussed. The reports and studies presenting evidence for these changes are scattered and often rather technical. I would hope to bring together what we now know for consideration.
Of course, the increased heat is potentially very destructive, but there are several probable effects which could be as bad or worse, but most people don’t seem to have heard about them yet. This article is a bit lengthy, so I ask you to persist.
Increasing sea level is already an established fact. According to British tidal records, it has been five inches in the last fifty years, seven inches since 1850. The rate seems to be accelerating. Sea level rise alone could erase at least 20 miles of the whole East coast and one third of Florida, for starters, but the loss of those communities would only be a part of the damage. The industrial sites and power stations near the coast and all port facilities would also be lost. Transoceanic traffic would be critically impaired. The economic cost of these losses are almost impossible to calculate, but there is more.
The change in general climate would affect the viability of existing farmland. Unless you eat rocks, you rely on farmers and the products of their land to stay alive. With increased heat and shifting rainfall patterns, the central part of the U.S., one of the highest productivity areas on the planet, could become a semi desert and no longer reliable for raising crops. A similar thing has already happened on a short term basis during the thirties. The same would be occurring at various, high productivity locations all over the world, and the social disruptions would be catastrophic and long lasting.
These two risks are serious enough, but there is one potentially much greater since it involves world wide extinction, and few seem to know about it — stagnation of the oceans. I wouldn’t want to alarm anyone except such a thing has happened before. Such an event may seem unlikely, but a past episode of global warming resulted in almost total extinction of species on land and in the sea. Let me provide a little background.
There is some form of life through the whole water column almost everywhere. This is only possible because the oceans’ waters contain enough oxygen to sustain life down to the bottom. From time to time in the past this has not been so, and the oceans have become completely stagnant, with oxygen breathing life possible only in near surface waters. Articles in Scientific American and other similar publications have described how such a thing has happened a number of times before, and we are at risk for causing it to happen again. I will use the well known Gulf Stream for my example of the process, but identical effects are found with major currents in both hemispheres since what I will describe is a world wide phenomenon.
The Gulf Stream begins in the Caribbean Sea as a current of warm, oxygenated water flowing as a river, heading North. It follows a route up the Eastern side of the Atlantic Ocean, South of Greenland, and heads toward the Arctic. All the way, the warmth of the water induces evaporation, and the Stream becomes more salty. In the Arctic finally the Stream cools off and being denser than the local water, it sinks. From there it flows Southward, rising once again near the equator, bringing oxygenated water to all depths. Once again, this occurs globally with many such currents, keeping all the oceans healthy for oxygen breathing life.
This conveyor belt which brings life to the deep oceans can be interrupted. If the Arctic ice were to melt off and the Northern ocean to heat up, the conveyor belt would stop, and everything other than surface waters would become anoxic, killing most of the life in the sea. Unfortunately, the predictions that global warming would be most pronounced at the poles have been proven right. Greenland’s ice sheets are melting off at a prodigious rate, and Antarctica is loosing massive chunks of glaciers. The real bad news is that the professionals’ estimate of the time line was too cautious and will have to be shortened considerably.
This is not merely theory. It has happened several times in the past, most catastrophically 252 million years ago at the end of the Permian era. That episode began with massive, long-term volcanic eruptions in Siberia which liberated enough heat trapping gasses such as CO2 to raise the global temperatures by 14 F. The poles heated up, and as the oceans stagnated, up to 96% of the life in the seas died off. We know what happened because the various layers in deep ocean cores preserve the chemical state of the water at the time as well as a record of global temperature. The land animals were already trying to cope with high heat, and then it got worse.
There is a bacterium in the family of Chlorobiaceae which lurks now in a few stagnant areas at ocean depths and in a few other isolated places such as the bottom of the Black Sea. It is an early form of life which extracts a bit of energy from the reduction of Sulfur Dioxide to Hydrogen Sulfide (H2S), releasing this gas as a waste product. H2S is highly toxic to most life forms, and in high concentrations, it has much the same effect as Cyanide. In lesser amounts, it induces unconsciousness rather like hibernation, and if the supply remains constant, you never wake up.
This organism is killed by oxygen, so its habitat was always limited, at least while the deep ocean still contained this vital element. In the newly anoxic water it prospered, and approaching the surface, it had some sunlight which further accelerated its growth. The bacterium bloomed for an extended period of time, releasing tons of H2S into the atmosphere; and it left abundant biomarkers in the oceanic sediments deposited then.
About 70% of terrestrial vertebrates died off during this period, and the effect on plant life was possibly more severe. For quite a while, the most common life forms on the planet were fungi which feasted on all the dead material. After several million years the H2S disappeared, the temperature went down, and complex life slowly renewed itself; but the losses had been huge. The sulfur spike left behind is attested in the geologic record as well as the extended period needed for recovery.
Global warming is not a hoax and it is not a joke. It is clearly a short term aberration with a conspicuous, immediate cause since the long term trend for temperature had been downward for millennia , declining from ca. 3000 B.C.E. toward another ice age several thousand years from now. (Graphic Data at this site. Scroll rapidly to see trend. Notice the kick after 1900.)
There have been natural episodes of warming in the past, and we know now that the results were mostly disastrous for our form of life, so I am not sure we should have a casual attitude about possibly causing another on our watch. The insanity of the situation is highlighted by the very corporate interests loudly demanding that global warming not exist as they are salivating to exploit the resources to be made available when the ice disappears. For them, it’s only the money, not evidence, not risk of catastrophe, not anything else.
I wrote this blog with considerable misgivings. It is not that our odds of survival have been changed by it, but that we can see that the price to pay for failure is much worse than we thought. However, I can offer this. Humans as a whole have shown a strong inclination to preserve their own interests, and most of us seem to know what is at risk now. Although many people think otherwise, I still see that we have enough time and ability to deal with the onrushing crisis, but as yet not the will. We still have those who stand in the way, arms crossed, yelling “NO” . Next to those individuals are the compromised politicians, the greedy titans of industry, all the willfully ignorant. These are loud and sometimes powerful, but they are very few. If we want our species to wind up as more than a shallow layer of organic material in the geological record, there is important work to be done. We need to move ahead.
We humans have faced worse trials in the past. The eruption of Toba 70,000 years ago nearly exterminated us, and we came back to occupy the whole Earth. That catastrophe fell on us unexpected. This time, because we can see what is happening, we have a chance to do right by ourselves in advance.
The central question is: Do we take control of our fate or merely suffer it?