The God Species_ How the Planet Can Survive the Age of Humans - Mark Lynas [27]
Biodiversity is an issue whose time has come. All we need to do now is figure out how to pay for it. Remember, all it will cost to save the tiger from extinction is a mere $82 million a year. Rather than passively lamenting its demise, we need to roll up our sleeves and start raising funds. If you do only one thing after reading this chapter, join this effort today.
BOUNDARY TWO
CLIMATE CHANGE
That climate change is a planetary boundary will come as a surprise to no one. What may come as a surprise however is that the target that has been advocated by not just governments, but environmentalists too, has for years been much too weak. More recently that has begun to change: Now an extraordinary coalition of more than a hundred governments and dozens of campaigning groups is lining up squarely behind a safe target for carbon dioxide in the atmosphere, as proposed by the planetary boundaries expert group. Although powerful countries like the United States and China are a long way from endorsing this target—and the world economy is even further away from meeting it—the fact that such a crucial planetary boundary has attracted such a strong level of support is a serious piece of good news and one that deserves celebration.
Previous chapters explained how humanity has risen to global prominence through a massive exploitation of fossil energy resources. Human civilization remains over 80 percent dependent on fossil fuels worldwide, and as the economy grows so does the rate at which the carbon dioxide resulting from the burning of coal, oil, and gas accumulates in the air. On average the carbon dioxide concentration of the atmosphere rises by about 2 parts per million (ppm) every year, from a preindustrial level of 278 ppm to about 390 ppm today. While the precise level of temperature rise implied by higher CO2 is always going to be uncertain, it is indisputable that—all other things being equal—global warming will result from the human emission of billions of tonnes of greenhouse gases, sustained over more than a century.
Arguments over what would be a “safe” level of atmospheric CO2 have raged for decades. Back in 1992 the UN Framework Convention on Climate Change required in its much cited Article 2 that the objective of international policy should be to avoid “dangerous anthropogenic interference” in the climate system—but without defining what “dangerous” actually meant. The British government’s Stern Review on the Economics of Climate Change of 2006 suggested a stabilization target of 550 ppm CO2e (carbon dioxide-equivalent, implying a bundling together of all climate-changing gases rather than only CO2). Two years earlier, the European Union had endorsed a target of limiting temperature rises to 2 degrees Celsius, implying—it was stated—a CO2 target of 450 ppm. This latter objective was endorsed in my 2007 book about climate-change impacts, Six Degrees, where I suggested that 2 degrees and 450 ppm were necessary to steer away from large-scale dangerous tipping points in the climate system. Major environmental groups also lined up behind similar targets, and pushed them hard at international meetings.
It turns out we were all wrong. A fair reading of the science today, as this chapter will show, points strongly toward a climate change planetary boundary of not 450 ppm but 350 ppm for carbon dioxide concentrations—a level that was passed back in 1988, the year that NASA climate scientist and planetary boundaries expert group member James Hansen first testified to the U.S. Congress that global warming was both real and already under way. Hansen has done more than any