Global warming General Scenario

Introduction : Due to intense human activity, in general, and consumption of fuels, the greenhouse gas i.e carbon dioxide in atmosphere is going up. The increase in absorption of the sun’s heat and consequent higher temperature of the atmosphere could have have drastic effect on entire global eco-system.
Global warming in the past : Scientist believes that universe created about 14 billion years ago and expanding since then.
There are 100 billion galaxies in the universe and each galaxy contains 200 billion sun like stars of different sizes.Many of these stars have the planets going around them, like the earth does around the sun.
Earth came into being 4.5 billion years ago. It was hot to start with and has cooled gradually. Life began on the earth about 3.5 billion ago and has, since then, undergone many changes resulting in many mass extinction events ( Holocene age,Tertiary cretaceous,Jurassic park,Triassic Permian,Carboniferous Devonian,Silurian Ordovician )
An extinction event is a sharp decrease in the number of species in a relatively short period of times,affecting mostly birds,mammals,reptiles,amphibians,fish and other simpler forms.
Main extinction causes include basalt eruption,global cooling or warming,asteroid or comet impacts and falling sea levels.
One of the most violent periods in the history of the earth is the disappearance of dinosaurs around 65 million years ago. They appeared around 230 million years back and were for almost 165 million years. During the period,they were not only roaming all over the world.