Video Introduction |

Source Code |

The **Kaya Identity** is a simple formula to project future
carbon emissions based on expected (or hoped-for) changes in
**Population** (in *billions*), economic activity as **GDP
per capita** (in *thousands of $US(1990) / person
year*), **Energy Intensity** in *Watt years / dollar*, and
the **Carbon Intensity** of the energy sources as *Gton C as
CO*_{2} per TeraWatt year.

*On the left, the GDP per capita as tuned to follow the past
historical trend. On the right, amounts of carbon-free energy needed,
in teraWatts or 10 ^{12} Watts, in order to stabilize
atmospheric CO_{2} at various levels between 750 and 350
ppm.*

There is no real strong constraint on how high the **Population** of the
Earth will rise to before it plateaus, which it hopefully will do although
this is not assured either. At any rate, feel free to dial your future
world population up and down without too much constraint from hard data.
Hopefully it won't go higher than 15.

The other parameters are unchanging with time as the model page loads.
Look at the model forecast for each, compared with data, by selecting
**GDP per Capita** for example in one of the two menus just above the plots,
or by mousing over the input box underneath the **$GDP/person** term in the
formula. One idea for predicting the future is extrapolating from the
past, which means adjusting the growth/decay rate until the solid blue curve
is a nice eyeball fit to the red data points. Do the same for the other
factors, **Watts/$** and **CO _{2}/Watt**.

This page runs its emissions predictions through
the ISAM model to calculate **atmospheric
CO _{2} concentration**,

Find the best-fit values for the various model parameters. This is basically a business-as-usual type of scenario |

Given the uncertainties in the best-fit parameters (by eyeball fit), what are the best and worst case scenarios for business-as-usual? |

Construct stabilization scenarios, limiting atmospheric CO_{2} to, say, 450 ppm. How much carbon-free energy would this require by the year 2100? |

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