Humans have farmed for thousands of years but in just the last few decades burgeoning populations have called for more agricultural ingenuity than ever before and subsequently agriculture becomes one of the causes of climate change. The breeding of new crop varieties, the use of fertilizers and pesticides and the bringing of more and more land under cultivation have kept production ahead of population growth throughout most of history which are the main causes of Climate change.. Since 1985, however, the limit seems to have been reached and per capita grain production has started to fall.
In 1987 world grain reserves were sufficient for 100 days; by 1989 there were only enough for 54 days, yet there are 100 million more people to feed every year. There have been hidden costs to the increases in productivity. It is thought that about 40000 people in the developing world die of pesticide poisoning every year and the pesticides also one of the environment hazards. Twenty four billion tones of top soil are lost from crop lands each year, eroded by wind and water.
Irrigation is lowering the water table beneath eight states in the Great Plains of the USA by a meter a year, and the diversion of rivers for irrigation in the former Soviet has reduced the Aral Sea to about a third of the size it was 25 years ago. One tenth of the Earth’s land surface is currently given over to agriculture but there will have to be yet further changes before food production is sustainable.