Millions of years ago, fire swept across the planet, fueled by an oxygen-rich atmosphere in which even wet forests burned, according to new research by new PhD graduate F. Garrett Boudinot and Julio Sepúlveda. The study, published today in Nature Geoscience, provides geochemical evidence showing that forest fires expanded dramatically, potentially burning up to 30 or 40 percent of global forests during a 100,000 year interval more than 90 million years ago. While today's fires are exacerbated by dry conditions, they found that forest fires during this period increased even in wet regions due to changes in global climate.