We must be a positive force of nature

Lorna Sutherland

Look around you. We are reshaping the surface of the planet on a geological scale - but at a far-faster-than-geological speed.In the last decade a new term has come into use to describe the epoch in which we live - "anthropocene", from the Greek roots anthropo meaning "human" and cene meaning "new".

Although there is debate in the scientific community about when human activities started to make an enduring mark in the earth's crust, there is a growing consensus that our recent rapid population increase (from less than a billion before the industrial revolution in the late 18th century to 7 billion today) and the economic development that has accowmpanied this increase, have made us a force of nature.

Look around you. We are reshaping the surface of the planet on a geological scale - but at a far-faster-than-geological speed. Acknowledging this represents a sea change in scientific thinking.

Human activity has, until now, been considered peripheral to the workings of the natural world, but the evidence driving this paradigm shift is abundant.

We have intentionally helped speed up the nitrogen cycle, which converts pure nitrogen in the air to useful chemicals, by an estimated 150 per cent. This has enabled a huge growth in population but has had unintended consequences such as run-off waters causing ever more "coastal dead zones" overrun by nitrogen-fed algal blooms.

The carbon cycle has similarly been tampered with.

Volcanoes are the planet's main "natural" way of getting carbon from the lithosphere into the atmosphere, but since the industrial revolution we have been helping them along via an ever-increasing rate of burning fossil fuels. The results of this are becoming apparent.

We have caused a dramatic increase in erosion and the denudation of the continents, which now exceeds natural sediment production by an order of magnitude. The construction of almost 50,000 large dams during the last 50 years have reduced the flow of that sediment by nearly a fifth. A knock-on effect of this is that many of the Earth's deltas, home to hundreds of millions of people, are eroding away faster than they can be replenished.

The list could go on. A massive body of peer-reviewed work by the Millennium Ecosystem Assessment on this subject can be viewed online at http://www.maweb.org. My impression from skimming this material is that no matter how beneficial projects are intended to be, there are all too frequently negative consequences down the line. This is partly because we just haven't thought things through and partly because the effects of our actions were unknowable at the time.

So what is to be done? This is the focus of much scientific discussion and debate.

A number of approaches have been mooted, from simple commonsense measures such as smarter farming and better sewage treatment to grand and frightening geoengineering projects which would attempt to actively reduce the amount of carbon dioxide in the atmosphere.

One thing seems abundantly clear. What is required of us now is a fundamental change in our thinking about the relationship between people and our planet. We all need to start thinking like conservationists. It is, after all, our own species we are conserving.

Lorna Sutherland has lived in many different places and always tried to pay attention to the changes in the natural environment around her.