Scenarios--or descriptions of possible future conditions--are essential tools in climate impact assessment.  Because climate change is expected to occur over a period of many years, it is important to consider that social and economic conditions will be changing at the same time.  Global, national and regional economies and societies have changed radically over the past century, and there is no reason to expect the rapid pace of change to slow down.  Of course, predicting such changes is not a simple task.  However, assuming no change in socioeconomic conditions may be just as inaccurate as our imprecise attempts to look into the future.

At least two kinds of scenarios are typically used.  First, climate change scenarios are used to describe the climatic conditions that might exist in the future, using a range of assumptions about emissions of greenhouse gases and other driving forces.  Second, baseline socioeconomic scenarios are used to describe how societies and economies might look in the future, in the absence of climate change.  These socioeconomic changes will affect the region's sensitivity to climate change, and its potential for response and adaptation. 

A third scenario type--environmental scenarios--describes future trends in non-climatic environmental conditions that are relevant to the particular sector under study.  Examples include changes in land use, changes in water quality, and changes in groundwater levels.  Further discussion of these scenarios, where appropriate, can be found under each the key topics. 

Last Modified: 12/03/1999