Our future lies inside these greenhouses. Ecologists at England's Lancaster University established one of the world's biggest solar dome complexes - 20 enclosures in all - to study the long-term effects of pollution. The scientists spread 8.5 tons of high-grade Kansas prairie soil inside a dozen of the energy-efficient glass structures and planted each with 44 trees. Then they pumped varying levels of carbon dioxide into the domes, simulating the projected atmospheric concentrations on Earth in 25, 50, and 95 years. For nearly two decades, researchers have theorized that forests could soak up CO2 from the air and store it harmlessly. Officials in Australia, Canada, Japan, and the US hoped this would allow their countries to meet Kyoto Protocol emissions targets without cutting consumption of fossil fuels. No such luck. The Lancaster team found that as greenhouse gas levels rise, plants and soil lose their ability to absorb and hold CO2. The scientists estimate that Earth's forests could be saturated by 2025. Well, at least there's plan B: Pump all that excess CO2 into the oceans.