People cannot help but change their environment. It is a characteristic we share will all other species. Change comes about because we need to acquire energy and materials to live, and these activities have an inevitable consequence for the environment. What sets us apart from all other organisms, however, is the scale and speed of the changes that we have initiated. There are few places on the Earth today that do not bear some trace of human activity. The impacts of modern lifestyles can now be seen by environmental changes going on at local, national and global scales.
Concern about the impacts of people on the environment has stimulated a good deal of scientific work directed at understanding the nature of environmental change, its consequences and what needs to be done to avoid its worst effects. In this chapter, we will look at some important computer-based technologies that have been used in such work. Our goal will be to consider how the technology has been used to monitor environmental change and help us to develop appropriate management strategies for the future.
The technologies that we will consider are those of geographical information systems (GIS) and remote sensing (RS). We need to understand these technologies because they have become important tools that can be used by geographers and other scientists to apply their knowledge to many of the environmental problems that confront modern societies. Figure 40.1, for example, shows the recent deforestation history of Madagascar. It is important to understand these types of change, because the world’s tropical forests are resources in their own right and because of the wide-ranging effect that such changes might have on global climates through the release into the atmosphere of the carbon stored in such ecosystems. Figure 40.2 shows data from a very different type of environment, namely that of central Asia. This map comes from a study that attempted to monitor land cover at a time when there had been a change in land holding and grazing patterns in some areas. These case studies are but two examples of scientists using map data to understand the nature of environmental change. In this chapter, we will consider some of the technical and scientific issues that lie behind such work.
It would clearly be a difficult and time-consuming task if data such as those shown in Figures 40.1 and 40.2 had to be collected by ground survey and drawn up by hand. Fortunately, we now have access to computer-based tools that can help to speed up the process. On the one hand, we have access to satellite and airborne remote-sensing systems that can automate the collection of data about the Earth’s surface. On the other, we have available computer-based systems, in the form of GIS, that can store, analyse and display such data, and link them with other sources of information. Figure 40.3 sets out the relationships between the processes of data