Scientists at the global footprint network calculate the energy component of our ecological footprint by estimating the amount of ecologically productive land and sea required to absorb the carbon released from fossil fuel combustion. this translates into 4.9 ha of the average american’s 7.2-ha ecological footprint. another way to think about our footprint, however, is to estimate how much land would be needed to grow biomass with an energy content equal to that of the fossil fuel we burn. assume that you are an average american who burns about 6.3 metric tons of oil-equivalent fossil fuels each year and that average terrestrial net primary productivity can be expressed as 0.0037 metric tons/ha/year. calculate how many hectares of land it would take to supply our fossil fuel use by present-day photosynthetic production.