TEMPE – With the latest report by the Intergovernmental Panel on Climate Change claiming with 95 percent certainty that human activity is the cause of climate change, supporters of renewable energy are renewing their calls for action. The Arizona Student Environmental Coalition is collecting signatures on a petition that urges the city of Tempe to increase its goals for solar power, just one of the ways the state can become a more sustainable by encouraging people to use renewable energy. Switching to renewables would reduce greenhouse gases that can lead to climate change, among other issues, the students say.