Nova Science Now had a great segment on tonight's show on mass extinction and how it relates to global warming. Scientists are trying to figure out the cause of the great extinction at the end of the Permian era 250 million years ago. This extinction wasn't like the mass extinction at the end of the Cretaceous that killed off the dinosaurs. This extinction killed over 90% of life in the oceans and most life on land.
There are many theories of exactly what caused this mass extinction, but one theory is a large build up of carbon dioxide in the atmosphere caused by volcanic activity. Being a greenhouse gas, high levels of carbon dioxide in the atmosphere trap in heat and cause the Earth to heat up. One of the interesting affects of the worlds oceans heating up is that warmer water holds less dissolved gasses and minerals. This is one of the reasons why warm pop or champagne is less fizzy than when it's cold. As the oceans heat up the water releases more and more of the dissolved gasses, including oxygen. With lower levels of oxygen aquatic animals have a more difficult time surviving. The interesting thing is oxygen depleted water is not devoid of life. In fact anaerobic bacteria thrive in oxygen depleted water. The byproduct of this bacteria is hydrogen sulfide, a nasty smelling deadly gas. If enough of this bacteria is present it can produce hydrogen sulfide is such large quantities that it will bubble to the surface and be released into the atmosphere. The hydrogen sulfide in the atmosphere not only would poison life on land, but would also damage the ozone layer allowing in more ultraviolet radiation.
This is an extreme example, but we must remember that life on Earth has existed for over three billion years. Humans have only been around for about 60,000 years. A mere blip on Earth's time-line. As one of the Earth's more recent residents we have managed to make major environmental changes, most within the last 100 years as we started burning huge volumes of coal and oil, destroying enormous forests, depleting the oceans of wildlife, and releasing such large volumes of carbon dioxide into the atmosphere that our current level is many times higher than the highest recorded levels of the past several thousand years.
As fossil records have shown us, mass extinctions have happened many times before and will happen many times to come. Life in some form always manages to survive. However human life is very fragile as we are susceptible to extreme temperatures, lack of oxygen, high levels of radiation, diseases, and many more. Artificially speeding up our extinction is foolish. It is imperative that we develop some type of technology to undo the damage we have done. Until that time we must for our own sake do what we can now to reduce the amount of damage we are inflicting on the environment before it's too late.