Global warming is good for you
The world's climate has always changed and that should not scare us. We should just be prepared
Duncan Steel
Thursday December 5, 2002
The Guardian
There can be little doubt that global warming is real. When scientists argue about the subject, it is usually in the context of how large a temperature rise they have calculated for the next decade or century, not whether any heating at all will occur. The heat is on, then. At least I hope so: because the greenhouse effect is a good thing.
Consider historical records, and other tracers showing how our climate has varied over the past few millennia. Stepping back just a decade, we find that injections of dust or smoke into the atmosphere, such as from the Mount Pinatubo volcanic eruption and the oil fires after the Gulf war, led to slight coolings (airborne particles reflect sunlight away). Going back to the 17th century, one notes the "Little Ice Age" when the River Thames froze over and frost fairs were held in London on its icy surface. This occurred during an era when there was a dip in sunspot numbers, and so was presumably caused by lessened solar output. Why, we don't know. But it happened.
Starting around AD540, pestilence spread across Europe. This is usually termed the Plague of Justinian (emperor of the eastern Roman Empire), and it was provoked by a climatic downturn. Similarly, several coincidental crashes of disparate, well-separated civilisations are recognised in archaeological records, for example around 1650BC and also 2350BC, with no apparent link other than widespread worsening climate.
So, relatively small perturbations in the amount of sunlight reaching the ground can lead to temperature falls sufficient to provoke the downfall of previously effective agricultural systems and economies.
Looking at the climate over an extended timescale, longer than the Holocene (the relatively warm past 12,000 years), one sees that the usual condition of Earth is far colder than that enjoyed now. The norm is Ice Age. Cool the climate just a little, and a feedback effect drops the temperature further: the Arctic snowfields creep further south and, because snow reflects away more sunlight than bare ground, the temperature drops lower, more snow falls, and on it goes.
Metaphorically, the global climate is similar to a cliff edge, next to which a drunk is staggering. One step in the wrong direction and over he goes. Although we'd all like things to remain the same, the reality is that nothing, most especially the weather, is constant. Coolings seem to be rapid, and cause disastrous downfalls of civilisation. But we can cope with slow upward trends in temperature. Our mantra should be slow change good, fast change bad.
Given that we cannot stop the occurrence of random steps toward the precipice, what we need to do is arrange for our drunkard to be a safe distance from the cliff edge. That is why global warming is a good thing. In fact, life on Earth owes its existence to the greenhouse effect. This became clear from investigations of other planets. It was by trying to understand why Venus has such a high surface-temperature (close to 500 C) that we learned how the terrestrial atmosphere keeps us warm, and realised that elevated levels of carbon dioxide from the burning of fossil fuels must surely push Earth's temperature up.
That our planet is subject to the greenhouse effect is not in doubt. The natural action of the atmosphere elevates the global temperature by almost 40 degrees. The moon is at the same distance from the sun as us, but much colder because it is airless.
When scientists debate the possibility of life on planets orbiting distant stars, they may ruminate on the "Goldilocks problem". The global temperature, like the porridge, must be "just right". But what is the "right" terrestrial temperature from the perspective of the development of civilisation?
That there are substantial drawbacks to global warming is unarguable. Certain low-lying areas such as Bangladesh and various Pacific islands may well be flooded. It will be the responsibility of the developed nations, which produce most of the carbon dioxide emissions, to find ways to assist those people most affected. But it is not only the developing world that will be inundated. For example, most of Florida, rather than just the Everglades, may become a swamp. In 100 years' time Miami may be submerged, but a century ago there was almost nothing there. Such change - slow change, on the scale of the human lifetime - causing the shifting of peoples has been a continuing feature of history.
In Britain the coastlines have never been constant: as Beachy Head erodes, it produces shingle that banks up to the east. The place where William the Conqueror landed in 1066 is now inland. Status quo is the exception, not the norm. For the human utility of the planet as a whole, some regions may need to be abandoned, while new zones of habitability will become available as planet Earth warms slightly. It is a natural function of humankind to move on, and search for new opportunities and horizons.
Global warming, then, is great because it protects us from the unpredictable big freeze that would be far, far worse.
* Duncan Steel is reader in space technology at the Joule Physics Laboratory, University of Salford.
[EMAIL PROTECTED]
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I don't understand why the Earth might stumble off another cliff, falling into a vicious circle of increasing temperature.
Jim Devine [EMAIL PROTECTED] & http://bellarmine.lmu.edu/~jdevine
