A Proposed Sustainable Development Indicator (SDI) is an indicator selected from the Candidate SDI List that most directly measures at least one aspect of sustainable development in the United States. These selection criteria ensure that a Proposed SDI represents a multi-generational, large-scale, high-cost (or high gain) phenomena most related to sustainable development. The Proposed SDI List is the total set of indicators that meet the selection criteria for a Proposed SDI. To select the Proposed SDI, first, select those endowments from the SDI Framework most critical to sustainable development. Then select those issues (and associated endowment characteristics) most crucial to sustainable development. Those critical endowments with crucial issues represent the Proposed SDI List.
While all endowments in the SDI Framework get passed on to future generations, some appear more critical to sustainable development than others. Four characteristics make an endowment ÒcriticalÓ to sustainable development: a national or global scale, a high number of dependent endowments, a long cycle time, and the existence of tipping points. The SDI Group must also consider issues (from the Candidate SDI List) critical to sustainable development. An issue crucial to sustainable development should meet four criteria: a declining endowment stock or capacity, a long social response time, an approaching endowment tipping point, and a high cost to future generations. The Proposed SDI List will focus on those critical endowments with key sustainable development issues.
To determine if an endowment is critical to sustainability, the SDI Group must consider the following four characteristics:
1) Scale: The physical or geographic extent of an endowment (local, regional, national, global). An endowment critical to sustainable development for the United States must be national or global in scale.
2) Dependent Endowments: The number of endowments dependent on proper functioning of this particular endowment. An endowment critical to sustainable development must have a high number of dependent endowments.
3) Cycle Time: The amount of time for an endowment to go through one complete, internal cycle (years, decades, centuries). Each endowment will have a cycle time that reflects the pace of its natural internal rhythm. For example, a forest ecosystem would have a cycle time of 30-50 years, the time required for a tree to reach maturity. The cycle time of culture may extend to hundreds of years. Most human-made capital has a cycle time of less than 10 years. Nuclear waste would have a cycle time of 10,000 years, based on the half-life of radioactive elements. An endowment critical to sustainable development must have a long, multi-generational cycle time.
4) Tipping Points: The "thresholds" beyond which small inputs can result in large changes (both positive and negative) to an endowment. An endowment critical to sustainable development must have at least one known or expected tipping point.
To determine if an issue identified in the Candidate SDI List is critical to sustainable development, the SDI Group should consider the following selection criteria:
1) Change in Stock or Capacity: Comparing the growth or reneneration rate to the use, consumption, or degradation rate determines if the endowment stock or capacity is decreasing or increasing. Rapidly declining endowments represent issues; stable and increasing endowments may represent opportunities. Endowment degradation may result from decreasing stocks, a decline in the quality, fragmentation, or inequitable use and distribution. An issue critical to sustainable development must reflect a rapid decline in an endowment's capacity.
2) Social Response Time: The SDI Group must know the social response time (years, decades, centuries) required to modify social behavior to reverse the decline of an endowment or improve an endowment. Modifications to social behavior may include changing the rate of consumption, adopting a substitute, or making a lifestyle change. If we cannot affect the rate of degradation or the regeneration rate, then the endowment change is irreversible and the only option is adaptation by substitution or changing lifestyle. The response time depends on the policy making process, the state of research and development, and the time required for the innovation to diffuse throughout the society. A critical sustainable development issue will have a short response time to create a long-term, big improvement in an endowment. A critical sustainable development issue also will have a response time much greater than the time until the endowment declines to a socially unacceptable level. Issues critical to sustainable development will typically have long, multi-generational response times. The more radical the behavior modification and the more time required to make it, the greater the issue.
3) Tipping Point Status: An endowment that lies very near its natural tipping point may indicate an issue. A tipping point is the "threshold" beyond which small inputs can result in large changes (both positive and negative) to an endowment. In both cases of declining and improving endowments, the rates of change may not be linear. Positive tipping points may occur when an endowment collects a critical mass of skill and resources to create a new capability, such as the Òinformation superhighway." Negative tipping points may occur when an endowment reaches maximum capacity, such as with environmental sinks. An issue critical to sustainable development must show an endowment lying very near and moving towards its natural tipping point. We are facing a major issue if business-as-usual practices will cause generation delay in arriving at a positive tipping point, or take us past a negative tipping point before normal response processes would reverse the decline.
4) Cost: Finally, the SDI Group should consider whether the costs -- social, economic and environmental -- of reversing a decline in an endowment, or the cost of reaching a higher level of endowment, will be significantly higher for future generations than the costs of taking action now. Cost can take monetary form for a government or for and individual (per capita). The loss of irreplaceable endowments, such as a work of art or an animal species, essentially have infinite cost. An issue can also have inequitable distribution of costs. An issue critical to sustainable development must have high social, economic, and environmental costs, especially for future generations.