This line, from The Guardian, says it all. The 21st century is not yet a dozen years old, and there are already 1 billion more people than in October 1999.
It took civilization until around 1804 to first amass a population of one billion. By the 1930's we'd doubled that. Just 30 more years and we topped 3 billion. And now we're at 7 billion heading to a possible peak of between nine and 10.5 billion by 2050. In the last 60-years the world has grown by 4.5 billion. Of course overall numbers alone don't tell the tale. They're massively compounded by our increase in individual consumption particularly over the past century. Each of us consumes vastly more than our great, great, great, great, great grandfather could and did. Think of us, in an overall sense, as 7 billion SuperConsumers. If you don't find that mind-boggling, you're not thinking this through.
Our diets, our modes of moving, and our urge to keep interior temperatures close to 70 degrees Fahrenheit no matter what is happening outside — none of these make us awful people. It's just that collectively, these behaviors are moving basic planetary systems into danger zones.
...[China], having grown demographically for millennia, is home to 1.34 billion people. One reason the growth even of low-consuming populations is hazardous is that bursts of per-capita consumption have typically followed decades of rapid demographic growth that occurred while per-capita consumption rates were low. Examples include the United States in the 19th and 20th centuries, China at the turn of the 21st, and India possibly in the coming decade. More immediately worrisome from an environmental perspective, of course, is that the United States and the industrialized world as a whole still have growing populations, despite recent slowdowns in the growth rate, while already living high up on the per-capita consumption ladder.
The United States has grown by more than 100-million since WWII but, with Americans' consumption rates, that represents about the same environmental footprint as one billion Indians.
...Fresh water is now shared so thinly that the United Nations Environment Program (UNEP) projects that in just 14 years two thirds of the world's population will be living in countries facing water scarcity or stress. Half of the world's original forests have been cleared for human land use, and UNEP warns that the world's fisheries will be effectively depleted by mid-century. The world's area of cultivated land has expanded by about 13 percent since its measurement began in 1961, but the doubling of world population since then means that each of us can count on just half as much land as in 1961 to produce the food we eat.
How we got to 7-billion is a story of conjuring acts on a whole civilization scale. It is a story of how we overpopulated, over exploited, over contaminated our environment, our biosphere. The Guardian article focuses on policies to address future population growth but, unless we do the things critical to living within our skin at 7-billion, it's really unclear that we'll ever reach anything approaching 9-billion much less the extreme estimate of 15-billion.
We are indeed ushering in the Athropocene, a new geological epoch characterized by a climate permanently altered solely by our species. In many corners of the world, including mine and possibly your own, the impacts of climate change are visibly, tangibly, palpably setting in and we know that, even if we halted carbon emissions today, the world will continue to warm for at least the remainder of this century. Yet the atmosphere is already too warm for us. We already have too much water vapour in the hydrologic cycle; water vapour that fuels severe storm events of increasing intensity and frequency; water vapour that changes precipitation patterns and delivers severe droughts and floods around the world.
It is pretty obvious now that we will ignore the warnings of the foremost climate scientists that we must wean ourselves from fossil fuels and that we have to give up coal and unconventional fossil fuels by 2015 - four years hence - if we're to have a reasonable chance of avoiding tipping points that will trigger runaway global warming. Even Germany is turning to coal to replace its nuclear power generation. Both India and China have massively expanding coal energy infrastructure. America, likewise, seems unwilling to replace coal with low-emitting renewables. And, in Canada, we continue to develop the filthiest, most environmentally ruinous fossil fuel on the planet - Alberta's and Saskatchewan's tar sands.
So it is unclear how we will ever stop overpopulating, over exploiting and over contaminating our environment on our own, somehow sustainable terms. So long as we continue to accept the nihilistic leadership of people like Stephen Harper or the US presidency and congress or China and India or most of the rest of the developed world, we won't even seek much less implement the long overdue measures that could possibly preserve most of the world's habitability. So the problem is not truly them - the Harpers, the McConnells, the Boehners and Obamas - it's us and our willingness to abide these types. Do you see that changing anytime soon?