Here is a graphic representation of Earth climate change(global temperatures) for the past 2500 years Global Temperature Trends Since 2500 B.C. Note the wide variations in actual temperature that occurred even before 1760 when the Industrial Revolution began and coal came into widespread use as the first fossil fuel. Petroleum was first discovered in the USA in the mid 19th century. This is why so many people question the idea that burning fossil fuels is responsible for global warming. The Earth's temperature goes up and down all by itself, even without us burning fossil fuels.