According to Lord Adair Turner, population decline should not be feared. It is certainly true that if the population of the UK were to shrink, so would our carbon emissions. Of course, this suggestion might have come with more authority if it had been made while he was still in post.
We have, in the last couple of centuries, unfortunately set up the financial world in such a way as to need a growing population. An increasing size of financial market in each country is required (according to current expertise) yet while there are some gains to be had in efficiency by each person, it is not possible for people to become more efficient endlessly. Furthermore, by this metric, a falling population would be a bad thing, as this would necessitate a shrinking market – even if it were shrinking slower than the population.
Perhaps our most problematic issue, is that our retirement system is set up on the basis of a larger number of young people supporting a smaller number of OAPs. Despite paying in to systems to provide a pension throughout our lives, this money rarely sits in a pot waiting for you. Instead it is used to run the country, and your pension comes out of taxes that are raised as you need to take out your pension. This works fine, until you have more pensioners than young people (something that is going to happen if we successfully reduce our population growth).
In Japan, women have an average of 1.36 babies, well below replacement levels. In the UK our rate is currently 1.6. This means that Japans population is due to shrink to 113.1 million from its current 125 million. The UK population is currently going the other way – it is predicted to grow by 5.2% to 71.7million though much of this is due to immigration (the replacement rate of birth is about 2.1 per woman).
The simple fact is that in order for the human race to thrive long-term we need it all: net zero emissions worldwide, a falling population, increasing areas of the world, with extremely low human populations (allowing natural ecosystems to recover) and far more efficient methods of growing food to feed our population without harming the planet – vertical farming and lab grown meat, are possibilities so long as they dont do more harm than good.