The renewable energy revolution that The Optimist Daily reports on every day, is beginning to have a real impact on global warming. During the first six months of the year, carbon dioxide emissions from America’s energy industry dropped to the lowest point since 1991, according to U.S. Energy Information Administration. That’s in part because warmer-than-average temperatures in the first quarter prompted fewer people to crank up their thermostats, lowering energy consumption. It’s also because clean energy production increased 9 percent, reducing the need for coal and natural gas. Emissions are on pace this year to hit their lowest annual level since 1992.