Measuring Man's Impact: Global Land Cover Change

The physical surface of the earth is in constant change: abundant water resources give rise to new growth, cities expand, what was once forest is converted to farmland. Man causes some of these transformations; others are merely the result of the changing of the seasons.

Most fundamentally, land cover is a way of portraying the surface of the earth. Often this is done through a process of classification where regions of the earth are identified according to some of their more prominent,quantifiable attributes.Researchers are frequently interested in how land cover changes in a given area through time (see below).

The use of satellite imagery has made the mapping of land cover much more practical. Currently, it is possible to look at land cover from global to local scales. This type of analysis has proven helpful to a variety of disciplines, from archeology to forestry to hydrology.

So how is our land cover changing or, more specifically...

What are the changes in global land cover and land use, and what are their causes?
How is the Earth's surface being transformed and how can such information be used to predict future changes?. (1)

With just cause, these two questions have been identified as top research priorities by NASA.s Earth Science Enterprise. The conversion of land cover from forest to urban land cover can be a good metric of urban sprawl. The influx of agricultural lands is a major cause of deforestation in certain regions of the world. The list continues and in many cases, questions pertaining to the variability of our earth.s surface are best answered through the analysis of its land cover.

(1) NASA, 1999, EOS Science Plan: The State of Science in the EOS Program. Washington, D.C., 397 pp.