Looks like Leonardo DiCaprio's mother is going to be a little bit lonely on Sunday. DiCaprio, perhaps Mother Earth's favorite son, intends to spend the day planting trees with the Los Angeles based group TreePeople. "We're helping reforest the decimated Southern California mountains. It's time to do what we can for the planet," says DiCaprio. Additionally, his global warming film, The 11th Hour, is slated to come out this fall. He's also rumored to be attached to a biopic about American conservationist President Theodore Roosevelt. Hopefully Mama DiCaprio has somebody else to go to brunch with…

There's no way around it: Your car is contributing to global warming. In fact, it's almost certainly the single most environmentally harmful component of your lifestyle. The transportation sector is responsible for nearly 40 percent of nationwide greenhouse gas emissions, not to mention plenty of ozone-damaging and smog-forming pollutants. The good news is that new clean-car technologies are emerging at a rapid pace – not just behind the scenes, but in the showrooms of car dealerships near you. Efficient hybrid-engine cars like the Toyota Prius and the Ford Escape SUV can't keep up with demand. Meanwhile General Motors and Ford are ramping up their development of flexible-fuel vehicles that can burn both standard gasoline and biofuels such as ethanol. So if you're in the market for a climate-saving, planet-positive vehicle, which should you choose -- better mileage or biofuel?