The Home of American Intellectual Conservatism — First Principles

December 17, 2017

FEATURE ARTICLES
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On Climate Change
P. E. Hodgson - 02/13/09

One way this could happen is if even a small change initiates a series of events that reinforce the original change; this is called positive feedback. It is a runaway process that continues until the system is destroyed. Some of these processes are already happening to our climate, and others are serious possibilities.

One example is the melting of the polar icecaps, which is already having devastating effects on people living in the Arctic. In several places their traditional method of hunting seals is no longer possible because the ice has melted. As the ice melts the albedo, a measure of the fraction of sunlight that is reflected, falls rapidly from 0.8—0.9 to less than 0.1 The result is that more sunlight is absorbed, melting more ice in a continuing feedback effect. This is one of the main reasons why the Arctic ice is melting so rapidly, thus providing a sensitive indicator of global warming. Some computer models indicate that by 2080 the Arctic will be ice-free in summer, making it impossible for the polar bears to survive.

Satellite observations have shown that the perennial Arctic sea ice covers about seventeen billion acres. This area varies from year to year, but in recent years the overall trend has been strongly downward, particularly in the Beaufort and Chukchi seas and also to a lesser extent in the Siberian and Laptev seas. The shrinkage now amounts to about 250 million acres.

Another example is the melting of the permafrost, a thick layer of frozen soil in the Arctic. This contains moss and lichen that has accumulated for thousands of years and frozen before it could rot. The dry weather has caused widespread forest fires in Alaska, and the temperature of the permafrost has risen by two or three degrees. It has been predicted that most of the top three metres of permafrost across the Arctic will melt during the present century. As the thawed vegetation finally rots, it will release ten of billion tonnes of carbon dioxide if there is oxygen present, and the far more damaging gas methane if it is not. This methane will increase the rate of global warming still further, melting the permafrost by a positive feedback loop.

Antarctica occupies 13.2 million sq.km., about 1.3 times the area of Europe, and the ice cap is up to 4 km. thick. No less than 90 percent of the world’s ice is in Antarctica, and if this were all to melt the world sea level would rise by 70 to 90 meters. However the ice in central Antarctica is at a temperature from–40 to–60 degrees and so is unaffected by a rise in temperature of a few degrees. The same applies to central Greenland which occupies an area about one-sixth of Antarctica. The ice shelves surrounding Antarctica are somewhat warmer, but are floating like the Arctic ice and so melting them has little effect on the sea level. However the sea level is affected by warmer coastal glaciers flowing into the sea from the ice caps of Antarctica, Greenland, and Northern Canada. The glaciers are very thick, and the pressure on the ice where it rides over the ground is enough to liquefy it, and this makes it easier for it to slide down into the sea. An additional effect has been suggested: when the surface of the ice melts, lakes are formed and this water flows down through cracks in the ice until it reaches the bedrock. There it spreads and reduces the friction between the ice and the bedrock, further increasing the rate of travel of the ice towards the sea. When this happens it causes the sea level to rise, but by an amount that is difficult to estimate. There is increasing evidence that the ice shelves are breaking up, and this reduces the pressure on the glaciers so that their rate of flow increases.

The possibility of another type of irreversible change is provided by the Gulf Stream, which warms northwestern Europe. Without it, the climate would be like that of Labrador, at the same latitude on the western Atlantic. At present the Gulf Stream brings warm water from the tropics toward Europe by what is called the thermohaline circulation. This is due to the freezing of the Arctic water, which causes the salt water to drain out of the ice. This salty water is heavier than fresh water and so it sinks, thus drawing warmer water northwards from the tropics. As this water cools it becomes denser and also sinks, thus attracting more warm water. If the oceans are heated by global warming and more freshwater enters the polar seas it could slow and even stop the Gulf Stream. This could cause the temperature to fall by six to eight degrees celsius and so it would then be frozen for much of the year, and London would become like Siberia.

Further evidence of major climate changes is provided by the melting of glaciers in the tropics. In many countries in the Andes and the Himalayas, the Arctic, Alaska, and East Africa, studies of ice cores and the glaciers themselves provide massive evidence of permanent changes. Isotopic analyses of the ice cores show the evolution of climate from the start of the El Niños about 5,500 years ago, the drought that terminated the Moche empire, and the current effects of global warming. The glaciers began to form in South America about 25,000 years ago and were followed by glaciers in other tropical countries. The growth of the glaciers depends on the latitude, and this is linked with the slow precession of the earth’s axis. During this period the latitude at which the sun was directly overhead moved steadily from the Tropic of Cancer to the Tropic of Capricorn. It might seem strange that glacier formation takes place predominantly when the temperature is highest, but this is because maximum sunshine brings maximum rainfall and at the altitudes where glaciers form the temperature is always low enough to freeze the rain, forming glaciers. The melting of glaciers right across the tropics is quite unprecedented and seems to be an irreversible effect of global warming.

About three billion people, half the people on the earth, depend on the monsoon rains to grow their food. There have been several failures in the monsoon rains in the last two centuries, and the resulting droughts and food shortages have killed tens of millions of people. The reasons for this variability are not entirely clear, but a connection with the El Nino current seems very likely. Famines in India occur during large fluctuations in the Pacific climate. A study of the strength of the monsoons over ten thousand years based on the amount of plankton in marine sediments showed that that weak summer monsoons are correlated with colder periods in the North Atlantic whereas strong monsoons occur when the Northern Atlantic seas are warm. It is not clear just why these effects occur or how they interact with each other. The effects may prove to be benign or catastrophic.

Can These Changes Be Stopped and Reversed?

Whatever we do, the amount of carbon dioxide in the atmosphere will inevitably increase. The danger of catastrophic climate change can be mitigated, however, if resolute action is taken to reduce carbon dioxide emissions. The first essential step is to replace fossil fuels power stations with sources that emit nothing or only minuscule amounts. Already, several countries have substantially reduced their emissions by building nuclear power stations. Thus France (80 percent nuclear) has halved their emissions, Japan (35 percent nuclear) by 20 percent, and the USA (20 percent nuclear) by 6 percent.

Several international conferences have been held to encourage nations to promise reduction. At the Kyoto Conference in 1997 Britain promised to reduce emissions by 20 percent by 2020. Already there has been a reduction by 6 percent due to the improved efficiency of nuclear power stations. As most of these are scheduled to close in the next few years, emissions are bound to rise. Both Britain and the USA have no hope of reaching these very modest targets.

The importance of the atmospheric half-life of greenhouse gases in the atmosphere is seldom recognised. Carbon dioxide lasts about a hundred years, whereas methane is mostly used up in a decade. A molecule of methane causes a hundred times as much global warming as one of carbon dioxide so methane is much more important in the few years after emission. Averaged over a longer period, the effect of carbon dioxide increases, so that over a hundred years the ratio of effectiveness falls to about ten. It is therefore of great importance to reduce methane emissions as soon as possible, although this was not recognized by the targets set at Kyoto. The reduction of methane emission from landfill sites, gas pipelines, coal mines, and many other sources would have an important effect in reducing global warming on the short term. Soot lasts only a few days in the atmosphere but has a large effect on global warming and so its emission should also be reduced.

During the next forty years about two thousand fossil fuel power stations must be replaced. This can be done in several ways. One is to build 4000 windmills occupying 500 square km each week. Or we can cover ten square km of desert with solar panels each week. Perhaps we can find more Severn estuaries and build barrages costing £9 billion every five weeks. Or finally, we can build fifty new nuclear power stations each year. This figure may be compared with the 43 that were built in 1983, the peak year for nuclear construction. This is the choice faced by world governments.

The next article will be devoted to an account of how governments have reacted to the world-wide threat to their very existence.

Notes:

  1. Sir Ghillian Prance, The Earth under Threat: A Christian Perspective (Wild Goose Publications: St Andrew’s Press, 1996).
  2. Brian Fagan, Floods, Famines and Emperors; El Niño and the Fate of Civilisations (New York: Basic Books, 1999). Brian Fagan, The Long Summer: How Climate Changed Civilisations.
  3. Bjørn Lomborg, The Skeptical Environmentalist (Cambridge: Cambridge University Press, 2004).
  4. Fred Pearce, The Last Generation (London: Eden Project Books, 2006).
  5. Richard A. Ker, “Is Katrina a Harbinger of still more Powerful Hurricanes?” Science 309.1807. 2005. P. J. Webster, G. J. Holland, J. A. Curry, and H-R Chang, “Changes in tropical cyclone number, duration and intensity in a warming environment,” Science 309.1844. 2005.
  6. John Houghton, Global Warming: The Complete Briefing (Oxford: Lion Publishing, 1994).
  7. James Lovelock, Gaia: A New Look at Life on Earth. 1979–2003. James Lovelock, The Ages of Gaia: A Biography of our Living Earth.
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