Donella Meadows' twelve leverage points to intervene in a system

Meadows worked in system analysis and proposed a scale of places to intervene in a system.

She started with the observation that there are levers, or places within a complex system (such as a firm, a city, an economy, a living being, an ecosystem, an ecoregion) where a "small shift in one thing can produce big changes in everything" (compare: constraint in the sense of theory of constraints).

She claimed we not only need to realise the existence of these shifts (or leverage points) but also to know where they are and how to use them. According to her, most people know where these points are instinctually, but tend to adjust them in the wrong direction. The understanding of these leverage points would be powerful information to solve major global problems such as unemployment, hunger, economic stagnation[?], pollution, resources depletion, and conservation issues.

After Donella Meadows developed an initial nine points list of places to intervene during a meeting, she detailed a twelve leverage points list with further explanation and examples, for systems in general.

She describes a system as being in a certain state, and containing a stock, with inflows (amounts coming into the system) and outflows (amounts going out of the system). At a given time, the system is in a certain perceived state. There may also be a goal for the system to be in a certain state. The difference between the current state and the goal is the discrepancy.

For example, one might consider a lake or reservoir, which contains a certain amount of water. The inflows are the amount of water coming from rivers, rainfall, drainage from nearby soils, and waste water from a local industrial plant. The outflows might be the amount of water used up for irrigation of nearby cornfield, water taken by that local plant to operate as well as the local camping site, water evaporating in the atmosphere, and trickling surplus water when the reservoir is full.

Local inhabitants complain about the water level getting low, pollution getting higher, and the potential effect of hot water release in the lake on life (in particular, the fish).

This is the difference between the perceived state (pollution or low water level) and the goal (a non-polluted lake).

Twelve leverage points to invervene in a system (in increasing order of effectiveness)

12. Constants, parameters, numbers (such as subsidies, taxes, standards)

Parameters are points of lowest leverage effects. Though they are the most clearly perceived among all leverages, they have little impact long term; they do not usually change behaviors. A widely changing system will not be made stable by a change of parameter, nor will a stagnant one dramatically change.

For example, climate parameters may not be changed easily (the amount of rain, the evapotranspiration rate, the temperature of the water), but they are the ones people think of first (they remember that in their youth, it was certainly raining more). These parameters are indeed very important. But even if changed (improvment of upper river stream to canalize incoming water), they will not change behavior much (the debit will probably not dramatically increase).

11. The size of buffers and other stabilizing stocks, relative to their flows

A buffer is a stabilizing stock. The stabilizing buffer is important when the stock amount is much higher than the potential amount of inflows or outflows. In the lake, the volume of water in the lake is the buffer: if there's a lot more of it than inflow/outflow, the system stays stable.

For example, the inhabitants are worried the lake fish might die as a consequence of hot water release directly in the lake without any previous cooling off.

However, the water in the lake has a large heat capacity, so it's a strong thermic buffer. Provided the release is done at low enough depth, under the thermocline[?], and the lake volume is big enough, the buffering capacity of the water might prevent any extinction from excess temperature.

Buffers may have great impact to improve a system, but they are often physical entities, where size is critical and can't be changed easily (for example, the lake capacity is restricted).

10. The structure of material stocks and flows (such as transport network, population age structures)

The structure of the system may have enormous effect on how the system operates. So it might also be a leverage point on which to act. However, if a system structure was not built properly, the cost, delays and externalities of the rebuilding may be prohibitive. Sometimes, the structure cannot even be changed at all. So the leverage point might be to understand the system limitations and bottlenecks, and to work on fluctuations.

For example, the inhabitants are worried about their lake getting polluted, as the industry releases chemicals pollutants directly in the water without any previous treatment. The system might need the used water to be diverted to a waste water treatment plant, but this requires rebuilding the underground used water system (which could be quite expensive).

9. The length of delays, relative to the rate of system changes

Another leverage point is in the length of delays. Delays must be carefully considered, as information received too quickly or information received too late could cause either overreaction and underreaction. Very lengthy delays cause oscillations when trying to adjust a system. However, delays are often parameters that can be changed as easily as rate of change.

For example, the city council is considering building the waste water treatment plant. However, the plant will take 5 years to be built, and will last about 30 years. The first delay will prevent the water being cleaned up within the first 5 years, while the second delay will make it impossible to build a plant with exactly the right capacity.

8. The strength of negative feedback loops, relative to the impact they are trying to correct against

A negative feedback loop is a control that tend to slow down a process (it refers to the direction of the change). In a system going forward, the negative loop will tend to promote stability (stagnation). The loop will keep the stock near the goal, thanks to parameters, accuracy and speed of information feedback, and size of correcting flows.

For example, one way to avoid the lake getting more and more polluted might be through setting up an additional tax, relative to the amount and the degree of the water released by the industrial plant. The tax might lead the industry to reduce its releases.

7. The gain around driving positive feedback loops

A positive feedback loop is a control that tends to speed up a process (it refers to the direction of the change). It is a self-reinforcing loop. Positive feedback loop are sources of growth, of explosion, and sometimes of collapse when the feedback is not under control (in particular of a negative feedback loop). Dana indicates that in most cases, it is preferable to slow down a positive loop, rather than speeding up a negative one.

The eutrophication of a lake is a typical feedback loop that goes wild. In an eutrophic lake (which means well-nourished), lots of life can be supported (fish included).

An increase of nutrients will lead to an increase of productivity, growth of phytoplancton first, using up as much nutrients as possible, followed by growth of zooplancton, feeding up on the first ones, and increase of fish populations. The more nutrients available there is, the more productivity is increased. As plancton organisms die, they fall at the bottom of the lake, where their matter is degraded by decomposers.

However, this degradation uses up available oxygen, and in the presence of huge amounts of organic matter to degrade, the medium progressively becomes anoxic (there is no more oxygen available). Upon time, all oxygen-dependent life dies, and the lake becomes a smelly anoxic place where no life can be supported (in particular no fish).

6. The structure of information flow (who does and does not have access to what kinds of information)

Information flow is a very important leverage point in a system. It is neither a parameter, nor a re-inforcing or slowing loop, but a new loop delivering information which was not delivered before. It is considered a very powerful leverage, cheaper and easier than infrastructure change.

For example, a monthly public report of water pollution level, especially nearby the industrial release, could have a lot of impact of people opinion toward the industry, and lead to changes in the waste water level of pollution.

5. The rules of the system (such as incentives, punishment, constraints)

Rules are very high leverage points. Dana Meadows points out the importance of paying attention to rules, and mostly to who make them.

For example, a strengthening of the law related to chemicals release limits, or an increase of the tax amount for any water containing by a given pollutant, will have a very strong impact on the lake water quality.

4. The power to add, change, evolve, or self-organize system structure

Self-organization[?] refers to the capacity of a system to change itself by creating new structures; adding new negative and positive feedback loops, promoting new information flows, making new rules.

For example, microorganisms have the ability to not only change to fit their new polluted environment, but also to undergo an evolution that make them able to biodegrade or bioaccumulate chemical pollutants. This capacity of part of the system to participate to its own eco-evolution[?] is a major leverage for change

3. The goal of the system

A goal change has impact on every item listed above, parameters, feedback loops, information and self-organisation.

A city council decision might be to change the goal of the lake from making it a free facility for public and private global use, to a more touristic oriented facility or a conservation area. That goal change will impact several of the above leverages : information on water quality will become mandatory and legal punishments will be set for any illegal polluted effluent.

2. The mindset or paradigm out of which the system - its goals, structure, rules, delays, parameters - arise

A society paradigm is an idea, an unstated assumption (for unnecessary to state) that everyone share. Thoughts, or states of thoughts which are sources of systems. Any set of assumptions becomes a paradigm, and therefore re-examining all the fundamental assumptions may lead to new paradigms. Paradigms are very hard to change, but there are no limits to paradigm change. It just requires another way of seeing things. Dana indicates paradigms might be changed by repeatedly and consistently pointing out to anomalities and failures to those with open minds.

A current paradigm is "Nature is a stock of resources to be converted to human purpose". What might happen to the lake were this collective idea changed ?

1. The power to transcend paradigms

Transcending paradigms may go beyond challenging fundamental assumptions, into the realm of changing the values and priorities that lead to the assumptions, and being able to choose among value sets at will. The power of this ability may be literally godlike.

Many today see Nature as a stock of resources to be converted to human purpose. Many Native Americans see Nature as a living god, to be loved, worshipped, and lived with. These views are incompatible, but perhaps another viewpoint could incorporate them both, along with others.

See also: focused improvement, constraint, theory of constraints, List of Management Topics