Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Sixth Wave of Extinction

20.07.2004


History of life on the Earth witnessed five mass extinctions of species as a result of natural calamities. Currently, biologists are talking more and more often about the sixth wave of extinction provoked in many respects by human beings. This opinion is shared by a Russian sea fauna diversity specialist A.V. Adrianov (Institute of Maritime Biology, Far-East Branch, Russian Academy of Sciences). Research in this area has been supported by the Far-East Branch of the Russian Academy of Sciences, CRDF, Ministry of Education and Science of the Russian Federation, and the Foundation for Promotion of Russian Science and the Russian Foundation for Basic Research.



As of today, taxonomists have already described nearly 2 million species, although in fact their number varies, according to various estimates, from 5 to 100 million. But 90 to 99 percent of species ever existing on the planet have already become extinct. The overwhelming majority vanished as a result of the so-called normal or background extinction due to the limited period of biological species existence, which fluctuates from 1 million years with mammals through 11 million years with some marine invertebrates. Besides the background extinction, the fauna experienced five mass extinctions, as a result of which 50 to 95 percent of then existing species disappeared within a limited historical period. The first mass extinction occurred 440 million years ago, at the end of Ordovic, as a result of temperature fall and the ocean level lowering. The second wave took place during the late Devonian, again due to temperature fall and sea reliction. During the third wave of extinction, at the end of Permian, approximately 250 million years ago, 95 percent of marine species and nearly 70 percent of terrestrial ones disappeared. The catastrophe was probably caused by active reconstruction of the earth’s crust and change of climate during formation of the supercontinent Pangaea. The forth extinction happened in the late Trias, and the fifth one – the most renowned extiction – hit 65 million years ago. Researchers are inclined to believe that the Earth came into collision with a large bolide at that time. As a result, sea shoals suffered from tsunami and acid rains, the seabed was covered by enormous amount of organic matter, and only 12 percent of the then existing species survived on land.

At present, according to numerous specialists’ opinion, the sixth - pleistocene - wave of extinction is coming, which has been in many respects provoked by men. Given the current average extinction rate of 40 species a day, it would take only 16 thousand years for the extinction of 96 percent of the contemporary biota – exactly as much as died out during the period of disastrous Permian extinction. The major reason for the oncoming calamity is destruction of plants’ and animal’s ecotope. Scientists have estimated that the species life span for contemporary mammals and birds has decreased up to 10 thousand years, i.e. it became 100 to 1000 times shorter than that of fossil forms. If the habitat continues to be destroyed at the same pace, the life span of these species will soon make only 200-400 years. There are no such estimates for the invertebrates, but they are undoubtedly affected both by the global environment and climate change, and by disappearance of local biotopes.


Death reigns on land and at sea. Thus, about 1 percent of tropical rainforests disappears annually. Up to 70 plant and animal species become extinct every day, which makes about 3 species per hour. At present, one tenth of coral reefs – zones of the highest biological diversity at shallow water – perishes; about 30 more percent will be ruined in the next decades. Corals die out mainly due to global environment and climate change, reef fish catching, water contamination and warming, hurricanes, destruction of symbiotic organisms. Any events taking place in shallow water also affects sea depths. Perhaps only “autonomous” superorganisms of deep-water gas-hydrotherm have not been touched upon by anthropogenic impact and they will evidently be able to escape consequences of the planet’s global environment and climate changes even in case of nuclear holocaust.

Nevertheless, the sixth mass extinction is oncoming. That will be the first extinction which did not happed due to natural reasons but as a result of activity of one biological species, whose quantity increases annually by 100 million individuals.

Sergey Komarov | alfa
Further information:
http://www.informnauka.ru

More articles from Life Sciences:

nachricht Small but ver­sat­ile; key play­ers in the mar­ine ni­tro­gen cycle can util­ize cy­anate and urea
10.12.2018 | Max-Planck-Institut für Marine Mikrobiologie

nachricht Carnegie Mellon researchers probe hydrogen bonds using new technique
10.12.2018 | Carnegie Mellon University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

Im Focus: Substitute for rare earth metal oxides

New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals

Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.

Im Focus: A bit of a stretch... material that thickens as it's pulled

Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.

Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...

Im Focus: The force of the vacuum

Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.

The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

Expert Panel on the Future of HPC in Engineering

03.12.2018 | Event News

 
Latest News

Small but ver­sat­ile; key play­ers in the mar­ine ni­tro­gen cycle can util­ize cy­anate and urea

10.12.2018 | Life Sciences

New method gives microscope a boost in resolution

10.12.2018 | Physics and Astronomy

Carnegie Mellon researchers probe hydrogen bonds using new technique

10.12.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>