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 Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>