OIL PALM: Transforming tropical forests into oil palm plantations, as seen here in Indonesia, and other land use changes are one of the largest sources of greenhouse gas emissions from human activity. Image: © iStockphoto.com / Vaara
Editor's Note: The following is an excerpt from Mark Lynas's book, The God Species: Saving the Planet in the Age of Humans.
The vast majority of the planet’s ice-free land surface – 83 per cent according to one study (pdf) – is now influenced by humans in some way or another. Where I live, in the British Isles, no part of the landscape is totally unaltered by people. The Lake District, for example, if left ungrazed by sheep, would revert to dense woodland on all but the highest peaks. Throughout the entire United Kingdom, the only species that have survived into the modern era are those that are able to coexist with human domination of the land: others, from beavers to wolves, have been extirpated entirely.
Human impacts on land may be much greater than is obvious at first sight. Roads, for example, appear to directly affect only a relatively small strip of land, but they also cut ecosystems in half, altering the survival prospects of species living on either side of them. With an estimated 1 million animals killed every day on America’s road network, the effect of this constant removal of predators and prey is felt over much wider areas. A seminal 2002 study of the ecological effects of a busy four-lane highway in Massachusetts found impacts – varying from wetland drainage to noise – across a broad 600-metre corridor. The consequent nationwide effects over the United States’ entire 6.2-million-kilometre road network can only be guessed at.
Whilst busy paved roads are a recent phenomenon, general human transformation of the land surface has been accelerating for millennia. The Roman empire deforested large areas around the Mediterranean, contributing to soil erosion and declining fertility. The European continent’s landscape changed dramatically between ad 500, when it was still four-fifths covered by swamp and woodland, and ad 1300, when half of this natural land had already been converted to agriculture. This transformative process fluctuated in lockstep with human population growth: when the Black Death killed a third of Europe’s population in the early fifteenth century, forests stopped their decline and began to regrow. To this day, many of Germany’s most valued ‘natural’ woodlands owe their existence to the depopulation wrought by the medieval plague.
With so little of the Earth’s land still pristine and unaffected by humans, the idea of the ‘wilderness’ has less and less meaning in the modern world. Indeed, if pollution and climate change are taken into account, no part of the planet’s surface is any longer truly wild. This does not mean that we must gloomily accept the continuing diminution of semi-wild areas and the erosion of the vital ecosystem services they provide. It does mean though that we need to challenge some orthodoxies that are no longer useful in this new era of near-total human planetary dominance. ‘Getting close to nature’ or going ‘back to the land’ will generally not be good for the environment, however psychologically fulfilling these objectives may be to individuals seeking escape from industrial living. Instead, we need to intensify agriculture and other human land uses in existing areas as much as possible, and encourage as an environmental boon the growth of the world’s major cities that already successfully concentrate today’s enormous human population onto only a tiny proportion of the world’s land. The most positive trend of all in allowing us to minimise our impact on the planet’s surface is one more often bemoaned than celebrated: urbanisation.