My latest research confirms that humanity remains on track to go extinct within a few decades as the result of our consumption and degradation of the natural environment, both directly and indirectly.
If our survival depends on keeping other species alive (those that directly support us, and those that support them), I now estimate that the combination of our consumption and worst-case global warming impact will drive us extinct by 2032; if not, then we'll have only another seven years. Without global warming impact, I expect humans will be gone by 2124 if killing those critical other species kills people; but if people can survive killing those species, then by 2160 over 29 billion people will be forced to live on fewer resources per person than anyone in history (with that consumption dropping rapidly).
The most reasonable expectation is that global warming will continue to increase for at least several decades, both in magnitude and impact; only how much and how fast is open for debate – until it happens, of course. While much attention has been rightly placed on this particular influence on our future, it is critical to keep in mind that it is a consequence, rather than the cause, of our imminent demise. The cause is humanity's pursuit of total dominance over the world, using its resources (living and not) to create environments suited to people's needs and wants. That pursuit unleashed the greenhouse gases now driving global warming, and it has diminished the ability of natural processes to compensate and keep that warming in check, all the while driving other species extinct at a rate that hasn't been experienced on our planet for many millions of years.
I was reminded recently of the slight chance for extending the lifetime of our species by leaving Earth, with the ultimate limits being the distribution of matter in the Universe and the laws of physics. Meanwhile, my research added a potential clue that humans might have natural limits built into our biology – first suggested by my study of the apparent relationship between happiness and consumption of natural resources – that will effectively cause us to starve ourselves under the most optimistic circumstances.
Use of this clue was behind my latest projections of population and consumption: that annual rates of change in world population and consumption (less so) are correlated with the total amount of those resources that we collectively consume. Those rates reached a peak in the 1960s, when we consumed two-thirds of the production of renewable resources by other species, and the consumption rate would plunge consumption to zero if we ever have the same amount left of total resources – which we won't because of how much we've already consumed, even if global warming spares us. Correlation is course not synonymous with cause, but it does beg for an explanation; and the hypothesis that our speed of growth is based on a basic sensitivity to how much of the world we use is tantalizing, to say the least.
We are still left with a range of stark options in the future of our species, just as each of us individuals must face the many different ways that we could die. The disturbing part now is how much they have in common, including timing, a conclusion I have been unable to shake after years of study and analysis.