Burning carbon-based substances like oil, gas, and especially coal, produces billions of tons of extra carbon dioxide each year. Methane gas from cows and pigs and other animals on our large farms ends up in the atmosphere as well, trapping more of the sun's energy as heat. Bill Nye
We're running the most dangerous experiment in history right now, which is to see how much carbon dioxide the atmosphere... can handle before there is an environmental catastrophe. Elon Musk
We have known since the 1800s that carbon dioxide traps heat in the atmosphere. The right amount keeps the climate conducive to human life. James Hansen
Plate tectonics is not all havoc and destruction. The slow movement of continents and ocean floors recycles carbon dioxide dissolved in the oceans back into the atmosphere. Without this slow speed carbon cycle, Earth's temperatures would cool dozens of degrees below your comfort zone. Seth Shostak
Natural gas emits only half the carbon dioxide of coal when burned, but if methane leaks when oil companies extract it from the ground in a sloppy manner - methane is far more potent a greenhouse gas than carbon dioxide - it can wipe out all the advantages of natural gas over coal. Thomas Friedman