Intense drought in South Africa’s Western Cape Province has led the world-renowned city of Cape Town to the brink of “Day Zero”—the date at which residents would be forced to collect strictly rationed water supplies from shared distribution taps. Water conservation efforts have so far prevented a massive water shutdown, but the city’s rapid population growth and reliance on surface water dams makes it particularly vulnerable to lower precipitation levels. 

The Lanjiang river in Eastern Zhejiang, China, reached its peak water level of 100 feet the night of June 25, 2017. Lanxi residents remember this day as “6.25,” marking the worst flood since 1955. Elsewhere in China that month, 7.3 million people were affected by floods, landslides, and heavy rains in northwestern Sichuan Province alone. Northern Guangxi suffered direct economic losses of 2.9 billion RMB (US$460 million). In the autonomous regions, 92,000 people were relocated. Flash floods caused the deaths of 10 people and forced 76,800 people to evacuate from Shanxi Province.

In 2014, we met with some of the technical leads of a major Chinese river basin authority in Beijing and asked them whether they were more worried about pollution or climate change impacts. Both, the engineers replied. Pollution affects us every day, they said, but changes in the climate erode our ability to supply drinking and irrigation water, manage floods, and generate electricity.

China must address its environmental and climate change challenges, such as reducing water pollution and building resilience to droughts, floods, and long-term climate shifts. But existing sources of finance have not met the growing demand for environmental projects.

Cape Town is running dry. But thanks to its sophisticated water management efforts, the city may ride out the crisis. However, other cities that lack these capacities are less likely to survive Day Zero. Especially in developing countries, where urban water services are often provided by informal or illegal actors, running out of water could have dangerous ripple effects for peace and security.

“Most risk in African cities is not catastrophic. It’s not even episodic, but it is every day,” said Mark Pelling, a professor at King’s College, London, at a recent event on urban risk and resilience in sub-Saharan Africa. With rates of rural-to-urban migration reaching record highs, more than half of the urban residents in sub-Saharan Africa live in informal settlements, where they lack basic infrastructure and access to critical resources. Integrated projects like Pelling’s Urban ARK seek to build more resilient communities in cities and informal settlements. “African cities are dynamic and are growing,” said Pelling—but so is the vulnerability of their residents to environmental change, natural disasters, and conflict.

Just days before the 2016 Summer Olympics began in Rio de Janeiro, the Brazilian city faced an unsavory problem: how to handle its overwhelming sewage. Nearly half of Rio’s municipal wastewater flowed untreated into Guanabara Bay, where the waters were so polluted by sludge that direct contact was deemed a health hazard to Olympic athletes.

$1 billion sales in two minutes. More than 250,000 purchases every second. Singles’ Day, China’s annual retailing extravaganza, absolutely crushes Black Friday: E-commerce giant Alibaba raked in $17.8 billion in gross sales during last year’s event, more than double the combined total of $6.8 billion in sales during the United States’ 2016 holiday shopping kick-off. The shopping spree lasts only 24 hours, but its environmental impacts will extend for decades.