BBC News Online environment correspondent
Humans have done too little
to find sustainable ways of sharing the Earth's resources, a US
Dr Peter Raven, says the rich world
in particular is not confronting the extinction crisis.
He believes we know scarcely 15% of
animal and plant species alive today.
And most of those we are driving to
extinction will vanish without us ever having known they were here.
Dr Raven is director of the
Missouri Botanical Garden and Engelmann Professor of Botany at
Washington University in St Louis.
He was delivering the Darwin lecture
in London on Wednesday, the eve of the UN-designated International
Day. His lecture
was entitled Our Choice: How Many Species Will Survive The 21st
Dr Raven said there were perhaps 10 million species alive today,
of which only 1.5 million had been recognised and named scientifically.
Humans knew no more than one in six
of the Earth's animal and plant species. We know so little about
fungi, he said, we had no accurate
picture of their geographical distribution.
In the tropical rainforests,
only one species in 20 had so far been catalogued, scientists estimated.
Over the last half-century, Dr
Raven said, drastic human changes to the Earth included:
* about a fifth of arable land lost to over-fertilisation, deserts
and urban sprawl
* roughly a third of the forests cut down and not replaced
* atmospheric carbon dioxide increasing by a sixth, contributing
to climate change
* the loss of 6-8% of the Earth's protective ozone layer.
We are using the Earth's productive systems at an unsustainable rate,
one that we cannot really afford," Dr Raven said.
We are likely never to have seen or to be aware of the existence
of most of the species we are driving to extinction."
not "morally or ethically right" to destroy things
as we were. Yet despite the 1992 Earth Summit, relatively little
progress towards sustainable development had been made.
said the industrialised nations had not generally risen to the
challenge - and if everyone lived at their standard, it would
take another two planets to support the Earth's population.
was simple and demanding: a stable population, a globally sustainable
consumption level, and acceptance of social
justice as the norm for development.
Dr Raven described the UK's
Darwin Initiative, which has provided £30m
($49.25m) to biodiversity conservation projects in developing countries,
as "a brilliant concept".
The meeting heard details of one Darwin-funded
project, which seeks to protect lion populations in Zimbabwe.
It is led by the Wildlife
Conservation Research Unit (WildCRU), University of Oxford, working
with theZimbabwe wildlife department.
Professor David Macdonald, director of WildCRU, told BBC News
think lions are common, but a survey to which we contributed came
up with a very different picture.
There may be as few as 20,000 lions left across Africa - a terrifyingly
small number, and a plausible one.
The lions we're looking at in Hwange are killed by farmers, and by
trophy hunters, and it's mainly males who die.
Lions live in extremely complex societies. If you kill one male,
the lion who replaces him will usually kill his cubs.
And we found males serving three, four or five prides of females,
not just one. So the take is completely unsustainable because the
consequences of one kill just cascade.
We've managed to get the hunting quota halved, and local youths are
getting the conservation message across in the villages."
Darwin project is trying to save the guanoco, an animal of the
high Andes which is thought to be the ancestor of the llama.
Other species to benefit include orang-utans
in Sabah, Malaysia, South African penguins, and fruit bats in Madagascar.