After the 1900's people started making factories and started using fossil fuels like coal, oil, and aluminum. It was the industrial revolution and overpopulation of humans that was the cause of the environmental problems that we have today. The reason our Earth is getting hotter is that human activities are emitting too much carbon dioxide into the atmosphere. The radiation from the sun gets trapped in the bag of carbon dioxide that surrounds our earth. One main reason for the problem of global warming is the burning of fossil fuels.
Fossil fuels are coal, oil and natural gases.
We use these fuels to run factories, power plants, cars, trucks, buses, air conditioning and etc. Seventy five percent of this is fossil fuels. For many years, scientists have been predicting that our disregard for Mother Nature would make the climatic temperature of this Earth to increase greatly. There have been arguments that the whole idea of Global Warming is a hoax, that the temperature cycle is just experiencing an upward trend and will eventually come back down. Now, however, we are starting to see the evidence of our behavior.