There is something that is very important for people to get their heads around. Peak oil is not about the oil, not about gasoline and diesel and heating oil and jet fuel. It's not about cars, SUVs, vans, trucks, buses, trains, planes or ships.
Peak oil is about food and our progressive inability, especially in the couple of decades after we pass the oil peak, to produce enough of it to feed our 6.5+ billion global population. Even now, every day over 40,000 people worldwide die of starvation, malnutrition and other nutrition related diseases. Each 1% gap between global demand and global supply will increase those deaths by 10-25%.
Food production in today's world is critically dependent on oil (for pesticides, herbicides, agrochemicals, agricultural irrigation and distribution fuels) and natural gas (for artificial fertilizers) and clean water from ever-scarcer and shrinking lakes and rivers and ever-shrinking underground aquifers. A shrinking global food supply is not just a problem for the third world. Everybody has to eat and we in the developed world tend to like to do that far more than those in the third world have the luxury of doing. Reversion to organic farming methods not dependent on artificial fertilizers and pesticides will not be as easy as the casual observer may think. Our commercial agricultural land is essentially toxic and sterile through our overuse of petrochemicals and limited-nutrient artificial fertilizers. Fertilizers are essentially Nitrogen, Potassium and Phosphorus. Plants, like people, need a full spectrum of dozens of different minerals and soil nutrients.
Commercial agriculture is essentially an export business, exporting the nutrients from the soil on which we grow the crops and never re-importing those nutrients. If the agrochemicals on which commercial agriculture relies were to disappear tomorrow, it is reliably estimated that those same commercial soils will produce only between 5-20% of the crops they do today, assuming even then that there is sufficient fresh water to irrigate them. It is estimated that it would take 10-20 years or more to rebuild the natural fertility of those commercial soils. Without those agrochemicals that means a drop of 80-95% in the productivity of those soils until their natural fertility is restored.
The other key factor, of course, is crop pests. Without oil-derived pesticides crops will be susceptible to invasion by those pests in numbers possibly never seen before. We have, through our use of pesticides, helped those pests evolve unprecedented resistance. Commercial farmers today use 33 times as much pesticides as just three decades ago and yet lose 25% more of their crop to pests than they did then. We are already losing the battle against crop pests. When the pesticides are gone we will lose the war.
That same use of pesticides has also prevented our crops from evolving their own natural defences against pests. Our current crops generally have very low survival potential without those pesticides. All of this, of course, parallels our own weakened immune systems because of the overuse of antibiotics, vaccines and other modern medicines, all of which take over the immune response rather than strengthen the immune system.
People will not really get it about peak oil and its serious implications for their own and their children's survivability until they get their heads away from worrying about transportation fuels and understand the implications for food in our world of 6.5+ billion people. We cannot simply wait until we are well past peak oil and on the decline downslope to start adapting to our changed circumstances.
Our current ability to feed most of our 6.5+ billion population has become dependent on a virtual carrying capacity. Modern, industrial agriculture has become increasingly and critically dependent on the production and application annually of millions of tons of herbicides, pesticides and artificial fertilizers, all derived from oil and natural gas. In the process we have destroyed the natural fertility of those soils. It will require decades of effort to rebuild that fertility to allow those soils to produce significant crops of food without those petrochemicals. If we wait until the feedstocks (oil and natural gas) for those agrochemicals are already in decline the tremendous loss of life while we rebuild the world's soil fertility will be unavoidable.