Thousands of years ago the first farmers burnt many hectares of virgin forest to clear land for seed planting. When after several years yields began to decline, they would clear more forest. Though there were few mouths to feed back then, agricultural methods were primitive and inefficient and the forest around must have seemed limitless.
According to recent research from the University of Virginia and University of Maryland-Baltimore County (USA), this activity may have sparked the climatic warming trend we still see today - although it has been vastly accelerated by the widespread burning of fossil fuels in the last two centuries. Ultimately both burning live forests, and burning fossilised forests in the form of coal or oil, add carbon dioxide (CO2) to the atmosphere.
Other contemporary research, this time from the University of Hohenheim (Germany), shows the increasing level of CO2 in the atmosphere looks set to affect wheat crops. As early as 2050 wheat is expected to become far less nutritious, with a lower protein content, 8% less iron and 14% more lead - all of which will be detrimental to human health. Other food plants - eucalyptus is one - will also suffer.
We may be able to excuse the first generation of farmers for their ignorance of CO2 and its effects on the climate. Today's generation of farmers, manufacturers, writers, advertisers, marketers, wastrels, speculators, miners, politicians, motorists, educators, actors, tourists, pilots and bloggers cannot be so excused.
The phrase 'we reap what we sow' comes to mind.