“Earth provides enough to satisfy every man’s need, but not every man’s greed.”
– Mahatma Gandhi
It is very clear that our lives and survival depend on the environment. At minimum, we need air to breathe, clean water to drink and food to eat. Because these resources exist on Earth in relatively large quantities it is not natural for us to think that there is only limited amount of each. These resources naturally renew so we can live sustainably as long as the rate of our consumption is not faster than the rate of their renewal. The equation is simple and we can influence all of its parts.
Average consumption per capita × Population ≤ Resource renewal rate
Opinions vary on whether we have already breached the balance, but the trend is clear: we are heavily increasing the left consumption side of the equation and reducing the renewal rate on the right side and thus disturbing the natural equilibrium. Our population is undeniably increasing, but also the average consumption per capita keeps growing. New technologies can help people in developed countries slightly reduce the consumption, but that will be offset by the increase of consumption in the much larger developing world. People in these countries generally feel it is only fair for them to reach the same standard of living (and therefore levels of consumption) that people have in the countries like USA before they start cutting on consumption. You can imagine how the consumption will grow when all Chinese and Indian install air-conditioning and buy a car every five years.
On the other side of the equation we are reducing the renewal rate. For example the more trees we cut in the Amazon, the slower renewal rate of clean air. The renewal rate of fossil fuels is extremely slow and negligible compared to their consumption so we will probably run out of them in several decades.
We don’t know how far exactly we can go, but the scariest part is that we are in a one-way street – many of the changes we inflict on Earth are essentially irreversible, so we can’t simply turn back when we realize that we went too far. It is alarming to see for example the dangerous reductions of biodiversity.
Nobody can predict what effects our behavior will have on the interconnected and fragile ecosystem that we are all dependent on. Nature had been able to adapt to changing conditions by the means of evolution, but the changes human inflicts on Earth are much faster than evolution can keep up with.
It seems inevitable that one way or another a huge reduction of population needs to take place and it is not going to be pleasant.