Here's yet another run at the perennial question of the importance of overpopulation versus overconsumption.
I wondered how much each nation in the world would contribute to the eventual ecological degradation of the planet given their current ecological footprint and their projected population growth between now and 2050.
To explore this I decided to use a variation on the familiar ecological "equation" I=PAT. In the original formulation, I is the impact we have on the planet, P is population, A is the per-capita activity level and T is the level of technology.
For this exploration, P is of course the population of the country.
For A (activity) I used the the current calculated per-capita ecological footprint (EF) expressed in in global hectares (Gha) per person.
I set T to 1 because I assumed a given country's ecological footprint would stay relatively stable over that period. That will of course not be true, and a range of values could be derived by varying T to reflect changes in EF over time. I held it constant to explore just the effect of population changes.
The output I is the total number of global hectares representing that country's ecological footprint.
Data:I found a list of countries with their per-capita ecological footprints
here.
I matched each country with its current population found
here and its projected population in 2050 found
here (based on the US Census Bureau's International Database).
The final list consisted of 150 countries with populations over 1 million.
You can find my original data and the calculations
here (XLS).
Method:I first multiplied the per-capita EF for each country by the its population to get the total number of global hectares needed by that country today and in 2050.
I summed each set of national numbers to get two total global values for the Gha needed today and in 2050.
I took the difference between the two national values to get the increase (or decrease) in total EF for that country over the next 40 years.
I took the difference between the two global values to determine the increase in total EF for the world over the next 40 years.
Dividing the national increase by the world increase gave the proportion of the total increase contributed by that country.
Results:While the world's population went up 38%, the global EF went up by only 26%. That confirms the fact that much of the population growth is happening in lower-impact countries.
It was not surprising that the United States contributed the lion's share of that 26% increase - virtually 30% of the increase was from the USA.
What did surprise me was that Ethiopia finished in the top 5 thanks to its overwhelming projected population increase.
Another thing that was surprising was that only 34 countries showed a net negative contribution to the global increase, and that only 4 countries - Italy, Spain, Russia and Japan - helped slow the increase by more than 1%
The best showing was from Japan, whose population decline gave them 4% net benefit.
Here are the top ten contributors: