Part 4

The Crowded Planet

Planets, so it turns out, are rather less of a rarity, rather less unusual than we had

once supposed. They have been discovered orbiting other stars elsewhere in the

cosmos. From 1995 to 2007, the number of known exoplanets – planets outside

our solar system – has gone from zero to more than two hundred. But Earth is an

inhabited planet. How unusual is that? We do not know, though the search for

extraterrestrial intelligence (ETI) continues apace. It may well be that in the vast

reaches of space other planets support living things. Whether such ‘‘life’’ would

resemble living things familiar to us is an open question. If such extraterrestrial

organisms do exist, they may have a basic chemistry and means of life quite unlike

anything we know on Earth. The flurry of excitement that greeted NASA’s announce-

ment in 1996 of life on Mars has now subsided. A number of observers now discredit

the evidence on which it was based.

So Earth, as of now, is the only living planet we have. In fact, the terrestrial

environment is such a perfect fit for life, that some use it as an argument for design,

in an argument that has become known as the Anthropic Principle, though others

regard such ‘‘fine tuning’’ of the laws of nature and terrestrial conditions with animal

life and human consciousness as a coincidence, an accident of cosmic history.

Whatever conclusion one reaches on this large question – this question of

questions – Earth is not only inhabited: it is crowded. When the first edition of this

book appeared in 1981, the Earth’s population was 4.5 billion. Twenty-seven years

later, it is 6.5 billion, and still rising, though the rate of increase has declined.

Two things follow. First, our dependence on Earth resources remains unchanged,

even though the particular resources we utilize may change with time (from tallow

to whale oil to coal gas to nuclear-fueled electric energy for lighting, for example).

Second, growing population produces not only growing demand for Earth resources,

but also growing stress upon the delicate systems and balance of Earth itself.

For though Earth is a resilient planet, the intricate equilibrium of its various interacting

systems is subject to changes, including long-term cycles, that are presently neither

predictable nor controllable.

The chapters that follow reflect these various concerns, not only with respect to

human history, but also to continuing resources and conservation.

Rhodes: Language of the Earth 9781405160674_4_012 Final Proof page 257 15.2.2008 3:48pm

Language of the Earth Edited By Frank H.T. Rhodes, Richard O. Stone and Bruce D. Malamud© 2008 Blackwell Publishing Ltd. ISBN: 978-1-4051-6067-4