Developed cities are spending a much larger percentage of their GDP than poorer cities each year on measures to adapt to the impacts of climate change, reports a paper published online this week in Nature Climate Change. The study suggests that spending is more strongly linked with protecting capital than helping the world’s most vulnerable people to avert the worst impacts of climate change.

The majority of the world’s population now lives in cities, with major urban centres increasingly at risk from extreme weather, water scarcity and energy shortages as a consequence of climate change.

Lucien Georgeson and colleagues analysed the amount that ten megacities (cities with a population greater than three million, or GDP ranking amongst the top 25 of cities, or both) across the globe spent on climate adaptation measures, such as better drainage systems, coastal defences and more resilient infrastructure. They found that ￡223 billion (0.38% of global GDP) was spent on climate adaptation worldwide in 2014/15, with the largest share of this spent in developed cities. Poorer and more vulnerable cities, such as Addis Ababa (Ethiopia), Lagos (Nigeria) and Jakarta (Indonesia), spent much less. New York (USA) spent the most overall (around ￡1.6 billion in 2014/15), Paris (France) spent the most per person (around ￡397.47), whereas Addis Ababa spent both the least overall (around ￡15 million) and least per person (￡4.71). They find that developed cities spend about 0.22% of their GDP on climate change adaptation, whereas the developing cities spend only about 0.15% (the exception is Beijing, which spends the most at 0.33%). The authors note that, taken together, this evidence seems to suggest that current adaptation spending tracks capital to be protected rather than people.

Spending on adaptation remains a small part of the global economy, but it is likely to rise. The authors call for international institutions to ensure that adequate funding is available to cities in developing and emerging economies, which are most vulnerable to the impacts of climate change.