A recent study has said that global warming caused by greenhouse gases can lead to drastic climatological, biological and other important changes around the world.

They probed a four- to seven-degree warming period some 55 million years ago during the closing stages of the Paleocene and the beginning of the Eocene eras, and used data for constructing a monumental reversal in the circulation of deep-ocean patterns around the world, triggered by global at that time.

The study in effect says that changes in the earth’s environment can trigger long lasting changes as had happened 55 million years ago, which changed the environment for close to 20000 years.

Researchers said that modern carbon dioxide input from fossil fuel sources to the earth’s surface was approaching the same levels estimated for the PETM period, and this was a matter of concern.