From: LARRY KLAES (ljk4@msn.com)
Date: Fri Dec 06 2002 - 08:36:52 PST
GLOBAL WARMING IS GOOD FOR YOU
>From The Guardian, 5 December 2002
http://www.guardian.co.uk/comment/story/0,3604,854050,00.html
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.
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