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.
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.
We have known since the 1800s that carbon dioxide traps heat in the atmosphere. The right amount keeps the climate conducive to human life.
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.
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.
On a per capita basis, Britain is responsible for more of the carbon dioxide now in the atmosphere than any other nation on Earth because it has been burning it from the dawn of the Industrial Revolution.
Carbon dioxide isn't the only greenhouse gas out there. Other substances, such as water vapor and nitrous oxide, also trap heat to varying degrees.
As a scientist, my attention became totally focused on global warming some 15 years ago by the elegant and powerful measurements of carbon dioxide trapped in ice cores taken as much as 2 miles deep from the great East Antarctica ice sheet.
Ocean acidification - the excess carbon dioxide in the atmosphere that is turning the oceans increasingly acid - is a slow but accelerating impact with consequences that will greatly overshadow all the oil spills put together. The warming trend that is CO2-related will overshadow all the oil spills that have ever occurred put together.
What makes tar sands particularly odious is that the energy you get out in the end, per unit carbon dioxide, is poor. It's equivalent to burning coal in your automobile.