Soils and climate change

World climates have changed many times over the last hundreds of million years resulting in dramatic changes to landscapes, vegetation, animal life and of course soil. These changes were caused by variations in the Earth's orbit in space. The last major climate change was an Ice Age about 2 million years ago. Over the last 20 years, following the warmest temperatures since recording began, major concerns have emerged that our climate is changing once again, but this time largely due to human activity, particularly to the burning of fossil fuels such as coal and oil. Scientists believe we are now entering a period during which climate change will occur faster than at any previous time, and these changes will have huge impacts on soils.

The Earth's surface is warmed by short-wave solar radiation from the sun. This energy drives most processes in the biosphere. As the radiation passes through the atmosphere towards the earth, some is reflected, some is scattered and some is absorbed but a proportion reaches the Earth's surface. Here, radiation is either absorbed or reflected. The solar radiation causes the Earth to warm up and give off its own thermal long-wave radiation. Gases such as carbon dioxide (CO₂), ozone (O₃) and water vapour in the atmosphere absorb some of this long-wave radiation reflecting it back to the Earth; the rest escaping into outer space. This reflection of thermal energy is called the Greenhouse Effect. Generally, incoming solar radiation is balanced by outgoing thermal radiation, maintaining the Earth's surface temperature at around an average temperature of 15°C. If some thermal radiation was not trapped, the earth's temperature would be below freezing.

The greenhouse effect of this warming caused by the interception of the long wave radiation by the natural so-called greenhouse gases is causing great concern among scientists. Human activity is undoubtedly bringing about the release of increasing amounts of gases into the atmosphere which increase this radiation back to the earth. These gases include carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons (CFLs), many of which are associated with industrial installations built in the last 150 years. Importantly, burning fossil fuels, such as coal and oil, releases carbon dioxide and other gases linked to the increase in greenhouse gases into the atmosphere. There is now scientific evidence that after being fairly constant for 1,000 years, atmospheric concentrations of carbon dioxide have gone up by 33% in the last 150 years!