The earth's resources are running out at an alarming rate. Four key resources in particular (oil, food, water, and fish) are due to become incredibly strained within our lifetime. If you don't believe me, check out the following article from gizmag, which breaks it down for you: http://www.gizmag.com/four-crucial-resources-running-out/12630/
An oversimplified summary of the article:
Depending on who you talk to, we have already reached or are nearing Peak Oil (the point at which it begins to take more energy to retrieve oil than to actually use it). As we know, the developed world, as it is today, is structured to be completely dependent on the use of fossil fuels. Combine that with rapidly growing populations and increasing standards of living in countries such as China and India, and we have an energy crisis on our hands.
Along with the issue of population growth, comes the matter of producing enough food to sustain everyone. We have already seen evidence of strains on world grain supplies in recent years. As demand for the limited food supplies has increased, the price of wheat and corn has tripled and the cost of rice has gone up 500% since 2005.
The need for more agricultural production brings with it demand for fresh water, not to mention the greater domestic needs as populations grow and climate change causes more and more weather extremes such as drought and floods.
On top of all that, the ocean's fisheries are not in such great shape. Since 1950, 30% of all fish species have seen a 90% decrease in their populations. Many countries remain lax on thier regulation of the fishing industry, allowing for undersize fish to be sold on the market, and preventing the ocean stocks from naturally replenishing themselves. In other words, when it is permitted for fish to be caught before reaching maturity and reproducing, the following generations become increasingly smaller, until they eventually cease to exist. This is the direction we are heading in.
However, all is not lost yet...The decisions you make in your daily life can have an impact and help to turn things around. Remember that you speak with your dollar, the things you choose to spend your money on (or not spend your money on) helps to shape the economy. Purchasing sustainably produced products and converting to renewable energy sources are a start. When you consolidate trips (i.e. instead of picking up the kids from school and then going grocery shopping later, plan it so that you do both things at the same time), you help reduce fossil fuel usage. Opting for a vegetarian option over meat (and especially fish!) reduces agricultural and fresh water demands. These may seem like small things, but they can really add up and make a difference.