Mongabay: In a speech Thursday, Al Gore challenged the U.S. to generate 100 percent of its electricity from zero carbon emission sources within 10 years. Speaking at Washington’s Constitution Hall, Gore said America’s security, environmental and economic crises are all related, and that measures to rein in greenhouse gas emissions will make the U.S. stronger, safer, and cleaner. “The survival of the United States of America as we know it is at risk,” Gore said. “I don’t …