The ideas of overpopulation, sustainability, and overconsumption have been studied for a couple hundred years. It is thought that the studies first began in the early 1800's when Thomas Malthus posited that humans were growing at a geometric rate (ie exponential), while their food supply was only growing at an arithmetic rate (ie linearly) (2). His claims were eventually found to be false, however they have had long reaching consequences in terms of scientific thought.
For example this influence can be seen in several peak theories which have come into prevalence. Namely, peak oil, peak water, peak phosphorous, and peak grain (345). The idea of peak anything is that the production of any good can only increase for a set amount of time before it decreases terminally (that is, the production will never increase after that point). Estimates on when these points will be reached vary (eg some think that oil has peaked already, and some feel it will peak sometime in the future), but these are still very serious issues which must be given deep consideration.
The only ways to combat the problems mentioned above, I believe, are research and education. Research must be done into ways to help alleviate current and future problems. For example, it is well known that there is a great food shortage in Africa. If we were able to say develop a new type of synthetic meat which could easily be created and distributed. Obviously we must always be looking for better and cheaper alternative energy sources. Education is also incredibly important. With the problem of overconsumption we must educate the people about how to get by on fewer resources. For example if the populations of China and India were to consume resources at the rate at which Japan consumes resources they would need an entire planet to sustain themselves (6). Another problem is that in countries which are not as well off economically the birth rate is generally much higher (7). It is generally accepted that with increased education and literacy rates there comes a decreased fertility rate (8). This comes from both increased female independence, and an increased knowledge of contraceptives. It has been shown that by increasing education women come to believe that they have control over their fertility rates instead of some god or other supernatural force.
Who knows what the future will bring. There may be more problems than solutions. We may not have a chance to save ourselves, but we have to try. There has to be something we can do.
One final, interesting tidbit. While doing research I found this one website (9). While you're there it tells you how many people have been born, how many people have died, how much topsoil has been eroded, and a few other things. In the time it took me to write this 77, 150 people were born, and 7,728 people died of hunger (on average anyway). It's kinda neat.