Simple population model
Here is an exercise for GSCE/A level/UG Geography students I developed for RIS (Researchers in Schools)
I like it because it speaks directly to students' futures.
- The UK is overpopulated in the sense that its current ecological footprint is significantly larger than its ecological capacity. This means that its population is consuming more environmental resources than are actually available to it. Are we all doomed? Let's find out.
Exploring the Data
The UK's current population represents a high water mark, and is due to go into steep decline as its rapidly ageing population dies off over the next 20-30 years leaving diminishing numbers of younger people with low birth rates in its wake. Germany and Japan are already beginning this decline. The US, Canada and Australia are only staving it off by mass immigration. Much of the developing world is just one generation behind. This is a natural transition related to "modernisation". Coupled with it is a pretty rapid reduction in environmental impact per unit of GDP production that’s been going on since the 1960's - at least in the developed world.
Model & Validation
Students construct a simple stepwise forecast model starting at 1900 of the UK's population, GDP per capita and total ecological footprint on a spreadsheet. In it people are born, have babies at a certain age and die at a certain age. Birth rates vary with GDP per capita modified by the GINI coefficient. This birth and death generates the population of the next timestep, from which GDP and ecological footprint can be estimated, and so on. Immigration of people in their 20′s is included, a proportion of whom settle permanently and have children too. All assumptions can be changed to investigate their impact and the model is validated against data from 1900 to the present.
Results & Conclusions
Provided there is
- immediate reduction in income disparity (down to current Scandinavian levels) - which boosts GDP and birth rates
- the rapid convergence on today’s environmental state-of-the-art (also Scandinavian) continues - no new inventions necessary
- increased short-term immigration - to get over the hump
the model trends suggest something like this:
So by about 2100, the UK should end up ecologically sustainable with a stable population of about 40 million pretty mobile, well off people.
Of course, everything depends on what decisions students make.
=> a super-exciting time to be starting out.