Once you have developed potential indicators, and have collected relevant data, it is possible to begin to analyse those data to identify and demonstrate trends. Readers with little or no experience with indicator development and data collection are encouraged to take time now to review Module 4 on Data and Indicators.
The integrated story, illustrating causality among key drivers and environmental states, is just the outer layer of the analysis. Beneath this high level integrated story are other stories more intimate in detail, which help us better understand what is happening to the environment and why. Getting to this next layer of information requires analysing the indicator to identify correlations, and to explain key temporal and spatial patterns.
A good place to start is the analysis of the state indicator to get to the core of the issue. The example below illustrates such an analysis for automobile fuel efficiency.
Case Example: Advanced
|Figure 12: Historical analysis of
on-road vehicle fuel efficiency in
Source: IISD and TERI 2002.
Identifying and explaining trends in on-road automobile fuel efficiency in Canada
Travel by automobiles is one source of emissions in Canada. The fuel efficiency of the fleet of automobiles on the road in Canada is one good indicator of this pressure. Figure 12 presents on-road fuel efficiency data for the period 1970 through 1994, along with data for vehicle stock and average vehicle fuel efficiency.
Consider a historical analysis as a first step in identifying and explaining trends in a pressure indicator. The sudden improvement in fuel efficiency realized in the late 1970s as illustrated in Figure 12 below, can be explained by the Corporate Average Fuel Economy (CAFE) standard that was adopted in the United States in 1975, following the 1973 Middle East oil embargo. In Canada in the 1980s, voluntary industry fuel efficiency targets were put in place through the federal government’s Company Average Fuel Consumption (CAFC) programme. Through the 1980s, a 55 percent improvement in on-road fuel efficiency was realized in Canada.
But, there was a sudden halt in fuel efficiency improvements in the 1990s. In looking at an indicator of the vehicle stock, we see a change from small and large cars to light trucks that were used as personal vehicles, and often called sport utility vehicles. In fact, it would also appear that the change in the vehicle stock during the 1980s (more small cars and fewer large cars) was a factor in the longevity of the on-road fuel efficiency increase experienced during the 1980s, aided by increases in the on-road fuel efficiency of both small and large cars during this time.
It would appear that the lack of improvement in on-road fuel efficiency in recent years late is due to society’s preference for larger, less fuel-efficient light trucks and sport utility vehicles.