AS THE POLICY debate over climate change unfolds, the Big Bet gets lost in the rhetoric. Congress and the American people are being asked to place a bet on how sensitive the Earth’s climate is to changes in carbon dioxide in the atmosphere. A wager on the low end could trigger the catastrophic events we all dread. The alternative, a policy that acknowledges how high and likely the risk really is, leads to the best possible future.
Policy experts seeking solutions to the threat of climate change are generally united on science but divided on policy. Some favour a carbon tax to drive changes in business practices and energy use; others favour a cap-and-trade system that puts a firm limit on CO2 emissions and harnesses market forces to drive change.
What they have in common is the data. According to projections by the Intergovernmental Panel on Climate Change, a doubling of atmospheric CO2 concentration would raise temperature by 3°C from pre-industrial times. With continued dependence on fossil fuels we are comfortably on track to exceed this doubling. And 3° is not in the middle of their likely range of 2°C to 4.5°C.