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Scientists all over the world use computer models to better understand the environment around us but what are they and how are they created? Research scientist, Diogo Costa, explains how these complex tools work.

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Kerbens Boisette:
Do you ever wonder how scientists figure out how to predict the effects of climate change?
Well you’re not alone, we received this question from Vaidik in Gatineau!

Vaidik:
How do we create computer models to forecast a changing environment?

Kerbens Boisette:
Good question! Research scientist, Diogo Costa, knows a thing or two about these computer models, otherwise known as, mathematical models. Diogo, could you enlighten us?

Diogo Costa:
The first thing to understand is what mathematical models actually are. A mathematical model can be a simple equation or a combination of many equations.

Now, our planet is a fascinating place, but it can be also a very complicated system where the weather interacts with our hydrological cycle which in turn interacts with our biogeochemical and ecological processes, so computer models of the environment tend to be quite complicated and involve many equations, particularly a set of equations that we call partial differential equations. In a sense, these mathematical equations relate properties of objects, forces, and states.

For example, Newton's second law of motion relates mass and acceleration of an object with the amount of force, of pull, of push, that is needed to accelerate it. So, as you can imagine, this can be very powerful.
In a sense, models for environmental diagnosis or forecasts are very similar to this example, they relate properties and forces in the environment. However, there are many processes that need to be represented in these models.
Imagine you want to develop the model to predict flooding. Well, you need to have multiple equations to predict each of the processes involved in the hydrological cycle which includes evaporation, evapotranspiration, precipitation, snow accumulation, blowing snow, snow melt, infiltration, stream flow, hydrodynamics instruments in lakes, groundwater flow, and on and on and on.

And the truth is that many hydrologists dedicate entire careers to study one or a few of these processes to try to find the most accurate way to represent the processes in these bigger mathematical models of the hydrological cycle.

Catchment hydrological models apply to all of these situations, each one representing one important process, so they try to mimic the hydrological cycle in a virtual way.

Kerbens Boisette:
Wow mathematical models are definitely complex, but it's amazing what useful and important information they can tell us.

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