Harvey’s scientific method was taken up by his pupils and successors and led to the discovery of carbon dioxide and oxygen and their role in animal metabolism. The carbon cycle was discovered in the 19th century and by the end of that century the role of carbon dioxide in the greenhouse effect had been demonstrated. The late 20th century saw the gradual appreciation that industrialisation and combustion of fossil fuels were making an important contribution to rising carbon dioxide levels in the amosphere and that the earth's capacity to absorb the excess was limited. We are now at a point where it would be seriously imprudent not to take global action to reduce emissions, in view of the likely consequences of further global climate change. All individuals in the prosperous world need to take action to reduce their carbon footprint; paying it lip service is no longer sufficient.
