Thirty-one scientists from 21 colleges and universities in Iowa have issued a letter to the Republican presidential candidates,  urging them to admit that the science of climate change is real. Many of the candidates have asserted that there is not a scientific consensus on the issue, even though scientists say that such a consensus exists. Gov. Rick Perry, for example, has called himself a "skeptic"  on climate change. Mitt Romney, the frontrunner, has in the past acknowledged climate change but of late has backtracked  from that position. The Iowa letter was drafted by four professors at Iowa State University. "We urge all candidates for public office at national, state, and local levels to acknowledge the overwhelming balance of evidence for the underpinning causes of climate change, to develop appropriate policy responses, and to develop local and statewide strategies to adapt to near-term changes in climate," says the letter.