By Sophie Hares
TEPIC, Mexico, Jan 31 (Thomson Reuters Foundation) - Equipping cities to cope with the predicted boom in urban growth poses a huge global challenge, with around two-thirds of people on the planet tipped to be city-dwellers by 2050.
Developing countries, in particular, are poised to see their urban populations soar.
Tackling the impact of exploding population pressure on transport and infrastructure, cutting levels of crime and social inequality, and improving health and housing are top of the list for the world's cities, along with preventing disasters and minimising the impacts of climate change.
Here are some facts and forecasts for the world's cities:
* Today around 54 percent of the world's population lives in cities, but that will rise to 66 percent by 2050. The United Nations says 3.9 billion people inhabited urban areas in 2015, and by 2045, over 6 billion will be city dwellers.
* Delhi is set to become the world's second-biggest city after Tokyo by 2030, with its population tipped to swell by nearly 10 million to 36 million, according to the United Nations. Shanghai is expected to claim third place, with Mumbai close on its heels.
* The 10 cities projected to become new megacities by 2030 are all in developing countries. They include Lahore in Pakistan, Bogota in Colombia, Luanda in Angola and the Thai capital, Bangkok. There are already 31 megacities worldwide, each home to over 10 million people.
* Around 80 percent of people in Latin America lived in cities by 2014, making it the world's most urbanised region. It also lays claim to having the biggest share of its population living in megacities.
* About 53 percent of the world's urban population lives in Asia, 14 percent in Europe and 13 percent in Latin America and the Caribbean.
* Over half of Africa's population lives in rural areas, according to the United Nations, which predicts the continent will see an 80 percent leap in cities that are home to over 500,000 people by 2030.
* Cities generate 80 percent of global economic output, but cover just 1 percent of the world's surface.
* The top natural risks for cities are floods, earthquakes and storms, with many urban areas vulnerable to climate-related factors such as extreme temperatures and water scarcity.
* Larger cities have a greater exposure to disasters, and the mortality and economic losses they cause, the United Nations says. Cities in less developed regions are also at higher risk.
* Cities account for around two-thirds of the world's energy consumption, and about 75 percent of its greenhouse gas emissions, according to climate research group CDP.
* Long-term sustainability doesn't come cheap, with $57 trillion needed by 2030 to build and maintain transport, energy, water and telecommunications infrastructure to keep up with global growth, according to McKinsey & Co.
* Urban housing pressure is immense, with nearly 1 billion people - a quarter of the world's city dwellers - living in slums. The United Nations estimates that number will triple by 2030. The bigger the city, the wider the gap in income levels and social inequality, experts say.
* The World Health Organization says 88 percent of city dwellers are exposed to annual pollution levels that exceed its air quality guidelines. Southeast Asia and the eastern Mediterranean have the worst air quality, followed by countries in Latin America and Africa.
* Mexico City, where citizens spend an average of three hours a day commuting, ranks as the world's most congested city, followed by Bangkok, Istanbul and Rio de Janeiro, according to a survey by navigational device company TomTom.
* Of the world's 50 most violent cities, 41 are in Latin America, with Caracas, Tegucigalpa, San Salvador and Acapulco ranking above South Africa's Cape Town and Kingston in Jamaica, according to a study by CCSP-JP, a Mexican NGO.
Sources: United Nations, World Health Organization, TomTom NV, World Bank, McKinsey & Co, CDP and CCSP-JP.
(Reporting by Sophie Hares; editing by Megan Rowling. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, climate change, resilience, women's rights, trafficking and property rights. Visit http://news.trust.org/climate)
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