In 2006, NASA's top climate scientist warned that we have at most a decade to turn the tide on global warming. After that, James Hansen said, all bets are off. Temperature rises of 3 to 7 degrees Farenheit will "produce a different planet."
More recently, Hansen's tone has become even more urgent. The melting of arctic ice is advancing faster than anyone predicted, indicating that we literally have no time to lose. The feedbacks triggered by even modest warming ? for example, as polar ice melts, the darker waters absorb more heat ? are pushing us toward a tipping point beyond which massive extinctions will become unstoppable.
If Hansen is right ? and most scientists think he is ? then every year lost is a year closer to catastrophe. In more positive terms, we have one last chance ? but no more than one chance ? to save the planet. If we don't do what needs to be done ? do it now and do it right ? we'll be powerless to avert disaster.
The question is, can we seize our historic last chance and not blow it? This question applies to humanity as a species, not to each of us as individuals. Changing our individual behavior can help, but is far from sufficient. The challenge we face is one of aggregate human behavior. Unless we fundamentally change our economic system, we have no hope of saving the planet.
But can we change something as vast and complex as our world economic system? It won't be easy, but I do think it's possible ? if we properly diagnose the problem.
What's the problem? For many decades, human emissions of greenhouse gases have exceeded the atmosphere's capacity to safely absorb them. Even though we know this, we don't stop polluting. The reason we don't is that, under our current economic rules, there are no limits or prices for polluting.
How might we fix this fundamental flaw? One possibility is rationing ? limit total use (in this case, of carbon) and give everyone equal usage rights. Rationing worked during two World Wars, but we're loath to use it again ? we prefer market mechanisms to government chits. Such a preference is fine, but only if we can devise an equally effective market-based way to limit carbon polluting.
The best and probably only way to do this, as I'll explain in a future blog, is economy-wide carbon capping. This means physically limiting the amount of carbon-based fuel that enters the economy each year, and cranking down that limit year after year until we reach a safe and sustainable level (which may well be zero). As the supply of carbon-based fuel declines, the market will decide who uses it, and which technologies will replace carbon.
Note that this economy-wide cap on carbon fuel supply is not the same thing as trying to cap carbon dioxide emissions at millions of individual smokestacks, flues and tailpipes; it's a cap on suppliers rather than on emitters. An emitter-based system involves far too much monitoring and administration, and will never catch all the carbon flowing into the atmosphere. The only leak-proof way to squeeze carbon out of the economy (and ultimately out of the atmosphere) is to catch it where it enters the economy in the form of oil, coal and natural gas. We must do this nationally first, and eventually internationally.
Installing this kind of economy-wide carbon capping system will not be painless, but it will be far less painful than letting the planet overheat. Moreover, the pain can be minimized if we design the system right. That means, among other things, making sure there's plenty of investment in clean alternatives, and helping energy users ? that is, all of us ? cope with the inevitable rise in energy prices.
The devil, of course, is in the details, and I'll explore some of those in later blogs. My point today is that we must act now, and we must get the system right. We can't afford to wait, and we can't afford to do it wrong. Leaky, emitter-based systems won't suffice. We must crank down the supply of fossil fuels, invest heavily in alternatives, and cushion the impact not just on the poor, but on everybody.