The explosion of human population in the 20th century was made possible by developments in technology that led to the rise of industrial agriculture with its huge machines, its chemical fertilisers and pesticides, its genetically modified crops, its extensive global transport systems. Industrial agriculture depends on cheap fossil fuels to power its operations and is a major contributor to the increased levels of CO2 in the atmosphere. Pre-industrial organic farming did the opposite. It sequestered CO2 and regenerated soil fertility in doing so. The Rodale Institute (see the video) is campaigning for a return to regenerative agriculture, still practised by farmers in the poorer countries, as a way of responding to the dangers of carbon emissions that appear to destabilising the global climate.