The Very Simple Climate Model

How much will temperature rise in the future? That depends on greenhouse gas emissions. Use this model to explore how the rate of carbon dioxide emissions affects the amount of CO₂ in the atmosphere and Earth's temperature. You can also explore scenarios for future climate using the model with more detailed instructions. Using the Very Simple Climate Model in the classroom? If so, check out the The Very Simple Climate Model Activity.

How does this work?

This climate model is very simple. It knows nothing of changing wind or precipitation patterns that might accompany and in turn influence warming; it doesn't care where the CO₂ is within the atmosphere; it ignores other greenhouse gases; and so on. In this simple model, the temperature is determined entirely by the atmospheric CO₂ concentration via greenhouse warming of the atmosphere.

This model displays carbon emissions as gigatons of carbon (GtC) but it is worth noting that carbon emissions can also be displayed as gigatons of carbon dioxide (GtCO₂). Around 80% of human caused greenhouse gas emissions are from CO₂, so much of the carbon being added to the atmosphere is in the form of CO₂. In this case, the model considers just the amount of carbon added to the atmosphere, which is less than the amount of CO₂ added to the atmosphere, because the mass of the oxygen atoms that make up the CO₂ molecules are not included.

While the assumptions behind this model are limited, they are valid. The starting values for concentration, carbon emission rate, and temperature are the actual values for the year 2015. The relationship between atmospheric CO₂ concentration and temperature uses a well-established relationship; basically, temperature rises about 3° C for each doubling of CO₂ concentration (the climate change sensitivity). So, for example, if the concentration goes from 400 ppmv to 800 ppmv, we expect to see temperature go up by 3° C.

The recommended temperature limit is shown as 2° Celsius above the pre-industrial level. Many experts now say this level should be 1.5° Celsius to avoid dangerous impacts of climate change.

For details about the math behind the model, see the Background section of the Very Simple Climate Model Activity.