How old will you be in 2300?

At international climate negotiations young activists have taken to wearing T-shirts stating "how old will you be in 2050?"  This is a particularly effective reminder for middle to late-aged politicians to think about the long-term - not just the short-term most politicians are typically concerned with.

So imagine my surprise in reading a United Nations report on population growth that produces scenarios all the way to 2300.

The report, for discussion in April at the 44th session of the Commission on Population and Development, provides interesting and sometimes surprising reading.  

Here are seven findings from the report - one for each billion people alive in 2011:

1. Fertility levels had declined in virtually all developing countries.  Yet, because declining fertility levels have generally been accompanied by significant reductions in child mortality, population growth has remained substantial.
2. In populations with low rates of child mortality, like Europe, women need to have 2.1 children to maintain a steady population size (excluding the impact of increased longevity and migration).  In populations with high rates of child mortality, such as the least-developed African countries, women need 2.5 children for a steady population.
3. There is a marked difference today between fertility levels of the least developed countries (4.4 children per woman) and the rest of the developing world (2.5 children per woman).  This compares with the current average of 1.6 children per woman in developed countries.
4. Today, 30 developing countries, representing 40 per cent of the population of the developing world, have fertility levels lower than what is needed for a steady population size (excluding longevity).
5. In developed countries, life expectancy is now 77 years.  In the least developed countries it is 56 years and in the rest of the developing countries it is now 68 years.
6. Different scenarios in the report suggest the global population could be 5.5 billion-14 billion in 2100 (medium scenario 9 billion) and 29.6-1.6 billion in 2300 (medium scenario 8.3 billion).  In Europe the range for 2100 is 609-782 million (medium 700 million) and 407-937 million in 2300 (medium 634 million). The current European population is 733 million.
7. Even with significant reductions in fertility levels, Africa's population will likely increase by 150 per cent by 2100 and many of its countries will see their populations increase four-fold or more.

The report rightly suggests population trends point to major problems in some areas of the world in the future.  It states that: "efforts to reduce fertility rapidly are especially needed in the fast growing countries of Africa and Asia.  In both major areas, but particularly in Africa, current fertility levels, if maintained, would lead to unsustainable numbers of people in the long run."

But what is also clear is that fertility rates have already significantly decreased in many parts of the world due to education, reduced child mortality and access to family planning.  In these areas fertility is less of a driver of population growth than longevity.  In Europe, fertility rates are currently so low that even with longevity factored in the population size may decrease.

What should we learn from this report?

I think it is clear that major efforts are needed in parts of the world to reduce population growth through education, family planning and reducing child mortality.  If this is done - which will require significant resources - it is very likely that the global population will peak around 2050 and then decline, perhaps significantly.

I think it is important that the debate on population is as focused on people's consumption, which the report touches on but doesn't address in detail.  Because although we do need to address the long-term issue of stabilising the global population the most pressing short-term issue is how to reduce the consumption of the richest billion people alive today who between them are responsible for around half of all greenhouse gas emissions. As John Lawton, Chairman of the Royal Commission on Environmental Pollution, said this week "The increase in affluence has a much bigger impact on the environment than simple numbers" 

And how old will I be in 2050?  The answer is that I will probably be dead, unless the average life expectancy in the UK increases substantially. Or I will have escaped to Sanctuary - anyone fancy watching Logan's Run?