Environmental modelling has little to do with green fashion

Image from treehugger.com

A model in the environment. Rarely do people venture into forests attired like this. While unrealistic, the model is used for a purpose. Similarly, environmental models are unrealisitc, but designed that way for a reason (image from treehugger.com).

Environmental modelling has nothing to do with green fashion. Or perhaps it does, but only obliquely – fashion models are usually stylised versions of reality (think make-up, air brushing, clothing that might not befit the conditions, etc). Somewhat similarly, environmental models are also stylised versions of reality.

A model of the Vasa, a Swedish warship from the 1620s. (Image from www.modelships.de).

A model of the Vasa, a Swedish warship from the 1620s (image from www.modelships.de).

A conceptual model of the carbon cycle of an African savannah. Williams et al. Carbon Balance and Management 2007 2:3.

A conceptual model of the carbon cycle of an African savannah (from Williams et al. Carbon Balance and Management 2007 2:3).

DNA_orbit_animated

DNA does not look exactly like this, but the model helps to understand DNA’s structure. (GIF by Zephyris at the English language Wikipedia).

Environmental models, as with other models, have their own particular purpose. A model of a Swedish warship wouldn’t battle a real Polish fleet. DNA does not look exactly like its model, yet the model helps to understand and communicate its structure. A model of the carbon cycle of an African savannah can help understand the main components of the system and how they are linked, but it is not the real cycle.

Perhaps the most naive criticism of an environmental model is that it is unrealistic. Such a comment is naive because models are meant to be unrealistic. You might think that more realistic models are always better. If so, you would be wrong, because models are designed to be imperfect descriptions of reality.

Hanna Kokko makes this point that models should be somewhat unrealistic with an analogy to maps. Imagine you are lost in the forest. A map, a model of reality, would help find your way home. You don’t need a perfect model of reality. A perfect model of reality would be identical to reality itself, and you have more than enough reality staring you in the face. In fact, it is the reality, so complex and cumbersome, that obscures the way home. To navigate efficiently, you’d need a sufficiently simple model.

If you were lost in a forest, find your way home with a map that subscribes to Hanna Kokko's approach to modelling. If it were too detailed, it would look like the forest itself. If it were too superficial, you might be none the wiser about where you. A good would strike the appropriate balance between complexity and simplicity for the task (adapted from Hanna Kokko's book Modelling for Field Biologists)

If you were lost in a forest, find your way home with a map that subscribes to Hanna Kokko’s approach to modelling. If it were too detailed, it would look like the forest itself. If it were too superficial, you might be none the wiser about where you were in the world. A good map would strike the appropriate balance between complexity and simplicity for the task (adapted from Hanna Kokko’s book Modelling for Field Biologists)

However, the model must not be too simple. To paraphrase Einstein, models should be as simple as possible, but no simpler. That is the crux of modelling – a modeller must find the balance between complexity and simplicity for the task at hand.

Another reason we need environmental models is that we often cannot afford to experiment with environmental systems in case our experiments have unintended consequences. Let’s return to the Swedish warship, which is the Vasa. Built over two years for King Gustavus Adolphus, the king wanted an impressive vessel, packed with many guns. It launched in 1628 to great fanfare.

However, the balance between lots of heavy guns above the waterline, and a fast and manoeuvrable warship was delicate – a little too delicate as it turned out. Less than a mile from its dock and with a couple of puffs of breeze, the ship leaned over, submerging its lower gun ports. Filling with water, the Vasa promptly, and ignominiously, sank.

A model of the warship – a physical model in the time of the Vasa, or a mathematical model in the modern age – would have been sufficient to help assess the ship’s stability prior to it being built.

The Vasa in real life, salvaged from off the coast of Stockholm, and now housed in the Vasa Museum (image from the Vasa Museum).

Think of the ship as the world’s environment. Would we want to test different options on the real environment, or test those options on models? With only one Vasa, and with only one world, it might often be prudent to assess options with models first, before implementing them in reality.

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