Life began some 3.5 billion years ago in the ocean of the primitive earth,
very different from what you see today.
Early forms of life were very simple single cell organisms.
Through [inaudible] time, other complex organisms evolved and eventually,
the diversity of life was able to inhabit lands and skies,
as well as oceans.
Many of these organisms such as the dinosaur, no longer exist.
Others that we know of today including ourselves,
have been around only for a few million years or less.
Extinction, the death of a species is as natural an event in evolution,
as the death of individual in demography.
So you might say,
why do we concern ourselves with current extinction?
Well, the problem is the rate of extinction today,
it is too fast.
At least a thousand times faster than the natural extinction rate.
What I mean by the natural extinction rate,
is the rate of a species,
is the extinctions that would occur if we humans were not around, I'm afraid that.
Unlike the mass extinction events of geological history, there were five.
The current extinction challenge is the one for which a single species,
humankind is almost wholly responsible.
And now, we are facing a catastrophic loss of a species, a biodiversity crisis.
Our current biodiversity crisis can be traced to four major threats;
Habitat loss, introduced species, overharvesting, global change.
The greatest threat is human alteration of habitat.
Aquatic biodiversity is also threatened by habitat loss.
For example, about 70 percent of coral reefs
have been damaged by human activities.
At the current rate of destruction,
almost half of coral reefs home to one-third of
mono fish species could be lost in the next 30 to 40 years.
Introduced species are known to have contributed to
about 40 percent of worldwide extinctions recorded since 1750.
Introduced species that gain a foothold in a new habitat may disrupt
the community by preying on or outcompeting native organisms for resources.
Overharvesting is when we harvest organisms at
rates exceeding the ability of their population to rebound.
Overfishing has already depleted some wild fishes to very low numbers.
Global change include alterations in climate, atmospheric chemistry,
and broad ecological systems that reduce the capacity of earth to support life.
Why do you think we should care about the loss of biodiversity?
Above all, biodiversity is good for ourselves,
because a variety of species bring us many practical benefits.
Many species that are threatened
could potentially provide medicines
and food for human use,
making biodiversity a crucial natural resource.
For example, about 30 percent of the prescriptions dispensed
from pharmacies contain substances originally derived from plants.
In food production, if you lose
wider populations of plants closely related to agriculture species,
we lose genetic resources that could be used to improve crop qualities,
such as disease resistance.
Indeed, plant breeders bred virus
resistant commercial rice by crossing it with white population plant.
Also, the loss of species means loss of unique genes,
which has potential for great human benefit.
In addition, as a member of the noble species, Homo sapiens,
let me give you a philosophical and moral justification by quoting G. H. Brundtland,
a former prime minister of Norway,
"We must consider our planet to be on loan from our children,
rather than being a gift from our ancestors."