Three critical numbers
Published Monday, August 6, 2012 in the New Brunswick Telegraph Journal.
If you are not a regular reader of Rolling Stone magazine, you might have missed a brilliant recent article by Bill McKibben, one of America’s most respected advocates for the environment. So here, in fewer words, is the gist of McKibben’s message about three critical numbers: 2°C, 565 gigatonnes and 2,795 gigatonnes.
The first critical number represents the maximum amount scientists believe our global temperature can increase before we get into very severe problems. Beyond 2°, weather extremes increase still more, sea level rise from melting ice accelerates and our climate potentially spins out of control like a snowball rolling ever faster down a hill.
The best possible temperature is the one we presently have –perfect for sustaining Earth’s complex and miraculous web of life. But it’s already rising. Emissions of carbon dioxide from our consumption of fossil fuels since the Industrial Revolution have already warmed our planet by about .8°C and it’s estimated that even if we stopped burning oil, coal and natural gas today, the momentum of what we’ve already put up into our atmosphere would increase temperatures another .8°C. That leaves us with little wiggle room, and segues nicely into the second critical number.
Scientists estimate that if we are to have any hope of hitting our 2° target, we need to limit global total emissions, from this day forward, to 565 gigatonnes (GT), or 565 billion tonnes.
That may sound like a lot, but at today’s level of fossil fuel combustion, it represents a much shorter timeline than one might guess. Consider this: global emissions in 2009 were 29 GT. In 2010, they were 30.6 GT. In 2011, they rose to 31.6 GT, the highest level ever. I really want to believe this trend will be reversed in 2012, but I don’t know of any reason to believe it will.
If you divide that global limit, 565 GT, by our 2011 emissions, 31.6 GT, you get 17.9 – the number of years it will take us to use up our limit at current emission levels. Every annual rise just has the effect of making that timeline shorter.
There’s one scenario that would absolutely guarantee that we come in under our limit, and that’s if the world were to run out of fossil fuels first. Brace yourself for the third critical number.
This is perhaps the scariest number of all. It’s our best estimate of the amount of carbon dioxide locked up in the world’s known reserves of coal, oil and natural gas. In other words, it’s our best estimate of emissions-in-waiting.
You’ve likely already noticed the problem. Burning every bit of coal, oil and natural gas we have will generate five times our emissions limit. There may be doubt about our ability to rein in emissions in time to limit warming to 2°C, but there’s absolutely no doubt that we have all the stored carbon we need to send our climate surging well past that limit and out of control.
Clearly, humanity needs to end its addiction to fossil fuels ASAP if it wishes its descendants to inherit a liveable planet. People far wiser than I suggest that globally we need to:
- Tax the bad and incent the good: implement taxes on carbon and all pollution, and use the money to spur the alternative energy and green technologies we need. Start low to ease the transition.
- End fossil fuel subsidies, the $500+ billion in annual handouts to some of the world’s wealthiest companies.
- Undertake a massive educational effort to explain the need for sustainability in all we do and get popular support for the huge task at hand. In an era marked by scientific illiteracy and a 140 character attention span, that promises to be an enormous challenge.
I’m a fan of clear, simple messages, and Bill McKibben’s Rolling Stone article presents our climate and energy reality in a pretty clear and simple way. I just wish it weren’t so damned stark..