Methane

 Whether it is oil or in gas form which goes up and plays havoc with the upper atmosphere at 84 time the rate of CO2, the cause of methane is animals and humans and decaying plant matter whether it is from today or from millions of years ago. When you use oil or gas in any form you are burning up plant and animal matter or even human matter from the present day to millions of years ago that has decomposed and reformulated itself over thousands to millions of years into methane Gas and oil.

Methane lately (because of Global Warming) is causing alarming changes simply because the warming is melting tundra and permafrost and ice further and further north which releases methane that has been locked in ice and Tundra for thousands and thousands of years whether it be trees or grass or animals like Mastodons or saber tooth tigers or even early humans.

So, the next time you fill up your car with gas for example, just realize what you are burning could also be the remains of your distant ancestors as well in the form of oil and gasoline. However, gasoline is highly refined with many chemicals added to process it into gasoline. But, basically you are burning trees and plants and animals and human beings from the distant past whenever you drive a car or truck using gasoline or diesel or even kerosene for jet planes.

But, methane is specific often to human or animals passing gas planet wide and when it isn't burnt up to take some other form in smoke it goes up and plays havoc with our upper atmosphere at about 84 times the rate of CO2 until it changes chemical composition into something else eventually through sunlight and bonding with other elements. in the air.

But, it is also present in it's most ancient form underground all over the world accompanying oil often in deposits around the world too.