The Revenge of Gaia
by Andrew Teller
Some books have such an impact on their readers
that they feel different after having read it: their outlook on
life or some long-held belief has been altered irreversibly. The
Revenge of Gaia is one of those. Like most people,
I had heard about James Lovelock and the Gaia theory, but I had
never got round to reading anything about it. James Lovelock’s
Revenge of Gaia is his latest book and, admittedly, his testament.
It is nevertheless a good place to start for an introduction to
his work in general and the Gaia theory in particular.
I must admit that I had always thought that all
the talk about global warming was a bit overdone and that gradual
changes in world climate would – in due time – lead
the lazy majority to mend their ways. This was until I started
reading in the above-mentioned book about how its author invented
Daisyworld in an attempt to justify his view of the earth as a
self-regulating organism. Daisyworld is a very simple and, therefore,
imaginary planet. It is populated by only two life species: black
and white daisies. The flowers are assumed to find all the nutrients
and water they need. Furthermore, due to their differing colours,
they reflect different quantities of sunlight and are, therefore,
able to alter the temperature of the surface on which they are
growing. James Lovelock and his colleague Andrew Watson went on
to write all the equations describing this simple ecosystem. There
are a dozen or so of them; they include energy balances and relations
describing how the planet’s temperature influences the flowers’
growth factors. Since the sizes of the areas covered by each species
vary and reflect different quantities of sunlight, the surface
temperature of the planet varies and in turn changes the growth
factors of the plants, leading to a closed-loop system. It must
be added that the equations describing the energy reflected and
the growth factors are not linear: the radiation emitted by the
daisies follows the well-known Stefan-Boltzmann law involving
the fourth power of the temperature and the flowers’ growth
factors involve the square of the temperature. All the ingredients
needed to give rise to a nonlinear system are there and a nonlinear
behaviour we obtain. To use James Lovelock’s own words,
the system so modelled is “stable, insensitive to initial
conditions and resistant to perturbation.” If the model
is instructed to increase the energy given off by the sun, one
does indeed observe that the planet’s temperature remains
remarkably stable for a fairly wide range of solar luminosity.
Beyond a given threshold, however, the self-regulating capacity
of the system breaks down; the temperature starts rising rapidly
so as to bring both species to extinction. Those who would be
tempted to believe that this exercise is purely academic please
be reminded that the heat emitted by the sun has been steadily
increasing since it first came into being.
Being somewhat familiar with nonlinear systems,
I immediately recognised this type of behaviour: relative stability
for a wide range of values of the controlling parameters and then
sudden departure from the former steady state once these have
exceeded a certain threshold. Since I was able to connect this
simple model1 to previous knowledge, it did more than
countless magazine articles to convince me that climate change
is a threat not to be underestimated. It drove home the conclusion
that the warnings of the climate experts might not give us much
of an advance notice.
Daisyworld provides a bare bones description
of the many closed-loop systems governing our ecosystem. A very
important one among them concerns carbon dioxide. This explains
James Lovelock’s decision to advocate the use of nuclear
energy which he sees, as the nuclear industry does, not as the
solution but, clearly, as part of the solution. He considers
that, if the problems of nuclear energy are certainly not to be
overlooked, they are nevertheless dwarfed by those that would
result from a failure to address climate change very soon and
with means commensurate to the extent of the threat.
Contrary to so many others who claim to be concerned
by global warming, James Lovelock has absolutely no taboo regarding
nuclear energy and he makes no bones about it. It is even remarkable
to see how outspoken he can be when it comes to justifying its
use. By contrast, the wording he uses highlights the extent to
which we members of the European Nuclear Society apply self-restraint
when we speak in favour of nuclear energy. There are many other
excerpts of The Revenge of Gaia worth
quoting here, but this would deprive you of the pleasure of discovering
them for yourselves. This is why I would rather encourage you
to buy and read it2 ; I am ready to bet that you will find yourselves
recommending it to acquaintances - as I am doing today.
1Feeding “Daisyworld”
in an Internet search engine will lead to numerous interesting
articles
2 James Lovelock, The Revenge
of Gaia, Allen Lane (Penguin Books), London, 2006 (176 p)
|
