Ancient man may have started global warming through massive deforestation and burning that could have permanently altered the Earth’s climate, according to a new study by researchers at the University of Virginia and the University of Maryland-Baltimore County. The study, published in the scientific journal Quaternary Science Reviews and reported on the University of Virginia’s Web site, says over thousands of years, farmers burned down so many forests on such a large scale that huge amounts of carbon dioxide were pumped into the atmosphere. That possibly caused the Earth to warm up and forever changed the climate