ULUTH, Minn. – Research by a University of Minnesota Duluth professor that separates Earth’s natural climate variability from outside factors points in particular to greenhouse gas-induced climate change as the likely cause of the warming planet. The study found that natural climate variability probably has helped keep things cooler in recent years than they otherwise would have been due to the outside factors. The research, published Sunday in Science Magazine, was headed by the University of Minnesota Duluth’s Byron Steinman, an assistant professor of geological sciences with the Large Lakes Observatory and the Department of Earth and Environmental Sciences.