log in

A changing world

Desertification represents one of the most significant future concerns for the land resource. Image credit: Bashir Nwer There is growing evidence that the world's climate is changing. It is a viewpoint that has been being voiced for some decades but has only started to be taken seriously since the 1970s. Since then there has been a large amount of research into climate change much of it driven by the meetings and proceedings of the Intergovernmental Panel on Climate Change (IPCC), the 2007 report of which involved over a thousand scientists. From a position of 'it may happen' there is now growing certainty that climate change is already happening. With the help of simulation models, predictions can be made of the changes that can be expected in global temperatures, rainfall and other climatic factors over the next 100 years. The changes now being predicted are likely to have a major impact on food production, sea level rise and low lying areas, water supplies and virtually all aspects of our life.

It will not be the first time there has been climate change in the geological history. Did you know that Britain, for example, once had deserts? Britain was also affected hugely by the Ice Age. However, what is different this time is the rate at which the changes are likely to take place; significant changes are expected to take place in the next 100 years The increased rate of change is attributed to the influence of humans whose greatly increased population and industrial activity have contributed significantly to the levels of potentially warming gases that have been released into the atmosphere, gases such as carbon dioxide, methane, nitrous oxides. (For more details of these see the sections in Soil-net on Global Cycles, Soil Functions, and Threats to Soils). It is now predicted that temperatures will rise by at least 2C on average in the next century. Already there have been temperature rises of an average of 0.7C in the last century. Changes in rainfall are more difficult to predict and are more variable from region to region. Many areas are predicted to become much drier.

The main gases that influence climate change are carbon dioxide, methane, nitrous oxides and chlorofluorocarbons. The soil is a major 'sink' for carbon, rather carbon is stored within the soil. The soil pool of carbon is over three times the amount of carbon in the atmosphere and over three times that in the plant kingdom. The fate of this carbon has the potential to greatly influence the content of CO2 in the atmosphere and hence future rates of climate change. The ability of soils to store carbon is being seen increasingly as a means of reducing the impact of climate change. Soils can also be a store for methane and nitrous oxides, and management of these in the soil can also reduce the impact of climate change. As well as being a sink for greenhouse gases, soils can also be an important source of them as they are released to the atmosphere.