the growth in the global ecological footprint since 1961 is largely a result of an increase in the global carbon footprint. as fossil fuel combustion has increased, what subsequent change has resulted in the rise of our global carbon footprint?

Google it that might work

Because a model would make the investigation easier to understand

The answer should be vaporization 

Okay well gravitational energy is matter forced by gravity making energy though the kinetic energy then the electric energy produces electricity from the kinetic energy and the kinetic energy gets its energy from the gravitational energy. was that the answer you wanted or something else?