Easy Way to Identify A System
From Thinking In Systems by Donella Meadows:
How to know whether you are looking at a system or just a bunch of stuff:
A) Can you identify the parts? AND
B) Do the parts affect each other? AND
C) Do the parts together produce an effect that is different from the effect of each part on its own? AND perhaps
D) Does the effect, the behavior over time, persist in a variety of circumstances.
Understanding System Behavior Over Time
Let’s look at a simple system as detailed by Donella Meadows, your bathtub. Systems can have one or more stocks. Stocks are just what you think, things you can feel, count, or measure at any given time. So for your bathtub, we have one stock, the water in your tub. Systems have inflows and outflows. For your bathtub, you have one inflow, the faucet, and there is one major outflow, the drain. We won’t concern ourselves with evaporation, since you will be out of the tub before much evaporation occurs. With the drain closed and the faucet off, it is an unchanging, benign system. If you turn on the faucet a bit, the water rises. If you turn the faucet on full, the water will rise more rapidly. The reverse is true for the drain. You could even have the faucet turned on at the same rate that the water is draining and have no change in the stock, the water level in the tub. As humans, we tend to focus on the stocks and not the flows, particularly the outflows. In our example, we can change the faucet or drain abruptly, but it is more difficult to change the level of the water, the stock. The drain will not work instantly to empty the tub. The faucet at full open will not instantly fill the tub. Stocks usually change slowly. “They can act as delays, lags, buffers, ballast, and sources of momentum in a system. “
Why is this important to understand? “We underestimate the inherent momentum of a stock.” An economy cannot build up broadly available new sources of energy overnight, e.g., solar and wind, even if lots of money is available. As Tampa is finding out, they can’t refill their empty reservoir overnight. China and the US continuing to build coal fired plants add to the fossil fuel plant stock we have to dismantle to eliminate the pollutants spewing into the atmosphere. Forests don’t grow overnight. Very scary, coral reefs don’t just grow, once they are comprised, we can’t get that stock back. “Changes in stocks set the pace for the dynamics of the system. The time lags that come from slowly changing stocks can cause problems in systems, but they can also be sources of stability.” Here in FL, aquifers don’t deplete immediately. However, years of taking more water from our aquifers than is renewed annually has led us to the position that our aquifers of fresh water are in jeopardy.
As Americans, we are even more handicapped on understanding the momentum stocks. Our culture is based on conquering our huge land mass (Westward Ho!) with seemingly limitless resources. We are the big is better people and the sky’s the limit. “The time lags imposed by stocks allow room to maneuver, to experiment, and to revise policies that aren’t working.” The time lag for us with so much in a great continent only now having us confront the limits of our stocks, i.e., having to change mental models that no longer apply. By improving our sense of the rate of change of a stock, we know better what to expect and may be able to use the system’s momentum toward a good outcome. However, as a world, we have used up a lot of the time that the time lags of our stocks were able to give us, whether that is fresh water, farmable land, or a life supporting atmosphere.
I like the simple example of the bath tub water stock because it is easy to extrapolate how difficult it is to manage stocks in complex systems with multiple stocks, multiple inflows and outflows, as well as multiple delays.
A Systems’ Behavior is Characterized by Its Feedback Processes
Understanding the role of feedback systems is critical to understanding the system behavior. We’ll pick that up in the next blog with a few more basics, like why complex systems oscillate and then review the basic system archetypes that you can apply every day in your thinking about problems and solutions within the complex systems you operate. We’ll also go back to some of the questions or issues raised in the first two blogs.
By Debbie Deland, Director of The 10% Initiative. She works with Green Cities Florida, the Chamber of Commerce, and NetImpact.
Tags: Sustainability, Systems Thinking
