Climate and other environmental changes

This chapter outlines the many environmental changes that have resulted recently from the burgeoning population of humans and their activities. Some of these changes are rapidly distributed around the globe: the most obvious of these are increased concentrations of gases such as carbon dioxide, methane and nitrous oxide in the atmosphere. These gases are of most relevance to gardening interests. One consequence of the combination of variable rainfall and warmer climate is that in the main growing period (May to September) water will evaporate from plants and soil more rapidly. This depletes the reservoir of soil water more quickly, with the result that plants require watering more frequently if their growth is not to be limited. As the population of the world has increased, so has the use of fertilisers (especially nitrogen and phosphorus), resulting in substantial changes to the global cycles of nutrients.