Opinion | As climate change makes itself felt through heatwaves and floods, are our mega-cities ready?

As the UK government finalises plans for the forthcoming COP26 climate summit, World Population Day tomorrow will underline how much demographic issues have risen up the political radar in recent years, especially on the sustainability front.

In part, this is driven by the fact that many countries, especially in the developing world, are seeking to redefine what sustainability means with their economic and population growth. This is helping drive the continued rise of the world’s population from around 7.7 billion today, to nearly 10 billion in 2050.

Yet this growth will not be distributed uniformly. According to the United Nations, more than half of it will be concentrated in nine countries, mainly in the developing world, but also including the United States, while in more than 50 countries or areas population is expected to decline, including potentially China.

Overall, growing populations are also driving another mega trend too: urbanisation. In 1800, less than 3 per cent of the population lived in cities, yet by the end of 2008, this had risen to 55 per cent, and there were 33 mega-cities (cities of 10 million or more inhabitants). The percentage of world population living in cities is expected to grow further from 55 per cent to 68 per cent by 2050.

Despite the economic success of mega-cities, governments are preparing for the growing risks that these massive urban centres pose. Key questions to be addressed include whether it will be possible to continually meet the everyday needs of food, water and health, and also deal with the growing vulnerability of large urban areas to environmental stresses exacerbated by the effects of climate change.

There is already cause for some concern, as shown by the heatwave earlier this month which saw temperatures reaching 20 degrees Celsius higher than normal in parts of the northwestern United States and southwestern Canada. Portland, a typically cool, wet US city, reached 46.6 degrees, which was hot enough to see roads buckling and power cables melting.