‘Climate change will not happen in an otherwise stationary system… The risks from climate change can be underestimated if no account is taken of people’s exposure.’

City in the rain

Credit: La Riposte

As outlined in our Resilience to extreme weather report, extreme weather has a huge impact on people’s lives and livelihoods. To make matters worse, climate change is likely to exacerbate this impact in the future. But another factor – population (numbers, composition and distribution) – will also play a major role in determining future risks.

When it comes to extreme weather, history leaves little doubt that population matters. Trends such as population growth (the global population grew from 1 billion in 1825 to 7 billion in 2011) and urbanisation (today, around 50% of the global population live in urban areas) have greatly influenced historic losses from extreme weather. And in the future the same will be true, with changes in population significantly increasing the number of people (and their assets) exposed to extremes.

‘In the absence of counteracting policy measures, human populations are likely to be growing, ageing and migrating towards urban areas leading to greater exposure to extreme weather.’

Table showing amplification of exposureThe double whammy of climate and population can be seen in this table, showing the number of times people’s exposure to extreme weather could be ramped up by the end of the century. See the scenarios used to crunch these numbers.

Alarming stats, I think you’ll agree. But this is just one reason why population needs to be a mainstay of the climate debate.

Another is that we’ve become accustomed to thinking about climate change in terms of global averages – ‘two degrees’ (the widely-touted ‘safe’ upper limit of global warming) is a familiar refrain. And yet average changes fail to convey the evidence that ‘the most extreme changes will occur where people live – on land.’ A predicted rise in global temperature of 4 degrees might sound bad enough. But factor in the faster rate that land heats up compared to oceans, and a 5.5 degree temperature rise on land sounds a good deal worse.

In brief? When it comes to tackling climate change and extreme weather, we ignore population at our peril.

For more on this, see chapter two of our Resilience to extreme weather report.

Read other posts in the ‘Resilience in brief’ blog series.