Friday, 23 May 2014

Conservation Thought for Today (2)

Biodiversity found on Earth today consists of many millions of distinct biological species, the product of four billion years of evolution. However, world extinction rates are going to be the next major issue for life on our planet. While we stand around wring our hands about global warming and other such issues. There is a ticking biological and ecological time bomb that is of our own making. The actual degree of biodiversity in terms of numbers and species on Earth is unknown. However, the level of decline into extinction of species is estimated to be between 1,000 and 10,000 times higher than the natural extinction rate. The natural or background extinction rate simply means the rate of species extinctions that would occur if we humans were not around.

"Scientists were startled in 1980 by the discovery of a tremendous diversity of insects in tropical forests. In one study of just 19 trees in Panama, 80% of the 1,200 beetle species discovered were previously unknown to science. Surprisingly, scientists have a better understanding of how many stars there are in the galaxy than how many species there are on Earth." World Resources Institute

You might think at first glance from reading the above that the number of new discoveries would significantly reduce the estimated number of extinctions. After all between 1.4 and 1.8 million species have already been scientifically identified. However unlike the mass extinction events we can see in earth's geological history. The current extinction challenge is one for which a single species (me and you) appears to be almost totally responsible. 

For instance that if the low estimate of the number of species is true. (that there are around 2 million different species on our planet) That gives a frightening prospect of between 200 and 2,000 extinctions occur every year. However, if the upper estimate of species numbers is true. (that there are 100 million different species on our planet) That then gives a much more terrifying prospect of between 10,000 and 100,000 species are becoming extinct each year.

We are all aware of what happened to the Dodo, a flightless bird that lived on the island of Mauritius in the Indian Ocean. The Dodo was about one metre tall and weighed in at around eighteen kilos. The first recorded mention of the Dodo was by Dutch sailors in 1598. In the following years, the bird was hunted by passing ships for food. The last widely accepted sighting of a Dodo was in 1662. The extinction of the Dodo came about within sixty five years of its discovery. This in turn focused attention to the previously unrecognised problem of human involvement in the disappearance of entire species. Science is starting to refer to human led extinction as the 6th extinction crisis, after the five well documented extinction events in geological history.

Since life began on Earth, several major mass extinctions have significantly exceeded the background extinction rate. The most recent, the Cretaceous Paleogene extinction event, which occurred approximately 66 million years ago. This was a large scale mass extinction of animal and plant species in a geologically short period of time. In the past 540 million years there have been five major events when over 50% of animal species died.

Cretaceous–Paleogene extinction event. About 17% of all families, 50% of all genera and 75% of all species became extinct.
Triassic–Jurassic extinction event. About 23% of all families, 48% of all genera and 70% to 75% of all species went extinct.

Permian–Triassic extinction event. Earth's largest extinction killed 57% of all families, 83% of all genera and 90% to 96% of all species.

Late Devonian extinction. About 19% of all families, 50% of all genera and 70% of all species.

Ordovician–Silurian extinction events. Two events occurred that killed off 27% of all families, 57% of all genera and 60% to 70% of all species.
We harvest an estimated 50,000-70,000 plant species for traditional and modern medicine worldwide. Yet we are allowing agri businesses to mess around with the genetic make up of many plants that provide our staple foods.  Huge areas of rain forest are being subjected to slash and burn to provide vast areas of monoculture for producing palm oil. 

In 2009, humanity used 40% more resources than nature can regenerate in a year. Using resources faster than they can regenerate and creating waste such as CO2 faster than it can be absorbed - is called ecological overshoot. We currently maintain this overshoot by liquidating the planet’s natural resources. We can cut trees faster than they re-grow, and catch fish at a rate faster than they repopulate. While this can be done for a short while, overshoot ultimately leads to the depletion of resources on which our our lives depend.

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