A large amount of money spent on measures to adapt to the impacts of climate change is more strongly linked with protecting big cities than helping the world's most vulnerable people to avert the worst impacts of climate change, according to a study published Monday in the journal Nature Climate Change.

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

A team led by University College London researchers analyzed the amount that ten megacities across the globe spent on climate adaptation measures, such as better drainage systems, coastal defences and more resilient infrastructure, according to the study. The researchers define megacities as cities with a population greater than three million, or GDP ranking amongst the top 25 of cities, or both.

They found that 223 billion pounds (310 billion US dollars), 0.38 percent 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 of Ethiopia, Lagos of Nigeria and Jakarta of Indonesia, spent much less. New York spent the most overall (around 1.6 billion pounds) in the period, Paris spent the most per person (around 397.47 pounds), whereas Addis Ababa spent both the least overall (around 15 million pounds) and least per person (4.71 pounds).

They found that developed cities spend about 0.22 percent of their GDP on climate change adaptation, whereas the developing cities spend only about 0.15 percent, with the exception of Beijing, which spends the most at 0.33 percent.

The evidence suggests that adaptation spending is driven by wealth rather than the number of vulnerable people, and it also indicates that current adaptation activities are insufficient in major population centers in developing and emerging economies, said the researchers.

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.