On Our Radar: Mock Candidates Go Head to Head on Energy Surrogates for President Obama and Mitt Romney debate the future of federal energy policy. E&E News Siemens begins testing the world's largest wind-turbine rotor, with blades measuring 505 feet. Clean Technica A growing majority of Americans -- 74 percent, up 5 points from a survey in March -- say that global warming is affecting weather in the United States. Yale Project on Climate Communication Researchers suggest that climate change could transform Central America's agricultural landscape by the 2020's, vastly reducing maize and bean harvests in one of the hemisphere's poorest regions. AlertNet A proposal for construction of two large apartment buildings on the banks of the toxic Gowanus Canal in Brooklyn, a federal Superfund site, stirs concerns about overtaxing sewage systems.