sustainable development

[Guest guest]

today's issue of science magazine is focused on sustainable development.

http://www.sciencemag.org/feature/data/sust/index.shtml#Commentary

Excerpts from: PRESIDENTIAL ADDRESS:

Science, Sustainability, and the Human Prospect

H. Raven*

" During the 1790s, the global population amounted to about 800 million

people. Despite the Reverend Malthus' dire prediction that population

growth would outstrip food production, we did limit the extent of starvation

during the 19th and 20th centuries, in large part because of the steam

engine and its successors. We manufactured increasingly toxic pesticides

with which we now douse our agricultural lands at the rate of 3 million

metric tons per year, worldwide. We are fixing nitrogen with an output that

exceeds natural processes. Cultivated lands have grown to comprise an area

about the size of South America. Rangelands occupying about a fifth of the

world's land surface support 3.3 billion cattle, sheep, and goats.

Two-thirds of the world's fisheries are being harvested beyond

sustainability.

Over the past half century, we have lost a fifth of the world's topsoil, a

fifth of its agricultural land, and a third of its forests. Grain production

has fallen short of consumption for two consecutive years, reducing the

surplus to the lowest level in two decades (1). We have changed the

composition of the atmosphere profoundly, driving global temperatures upward

and depleting stratospheric ozone. Habitats throughout the world have been

decimated by intentionally and accidentally introduced plants and animals.

Most troublesome is the irreversible loss of biodiversity. For the past 65

million years, the rate of species extinction has remained at about one

species per million per year. It has now risen by approximately three orders

of magnitude, to perhaps 1000 species per million per year (perhaps 0.1% of

all species per year), and it continues to rise as habitats throughout the

world are destroyed. Species-area relationships, taken worldwide in relation

to habitat destruction, lead to projections of the loss of fully two-thirds

of all species on Earth by the end of this century (2). And these

projections do not include the inevitably negative effects of climate

change, widespread pollution, and the destruction caused by alien species

worldwide, among other factors. In addition, the ecosystem services on which

all life on Earth, including our own, depends are being disrupted locally

and regionally in such a way as to deprive future generations of many of the

benefits that we enjoy now (3).

Considering the ways in which plants and animals enrich our lives, it is

incredible that we continue to destroy them so carelessly (4). The actions

that we carry out over the next few decades will decide the fate of millions

of species of plants, animals, fungi, and microorganisms, the greater number

of them completely unknown at present and likely to have remained so at the

time of their permanent disappearance from our planet.

Thus, the world has been converted in an instant of time from a wild natural

one to one in which humans, one of an estimated 10 million or more species,

are consuming, wasting, or diverting an estimated 45% of the total net

biological productivity on land and using more than half of the renewable

fresh water. The scale of changes in Earth's systems, well documented from

the primary literature by Pimm (5) is so different from before that we

cannot predict the future, much less chart a course of action, on the basis

of what has happened in the past (6). "

Full article:

http://www.sciencemag.org/cgi/content/full/297/5583/954

Suze Fisher

Web Design & Development

http://members.bellatlantic.net/~vze3shjg/

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