Randy Jackson, a professor of grassland ecology at University of Wisconsin-Madison who was not involved in the study, said he has found similar results in his own research showing that grass-fed beef has higher emissions assuming the same demand. In fact, Eshel’s team cited his work. But he worries that the study is too focused on minimizing emissions “without concern for the environmental impacts beyond GHG load to the atmosphere,” like biodiversity and soil and water quality, he wrote in an email.