This week, the Guardian’s international news magazine goes inside the next generation of places with more than 10m inhabitants. Subscribe to The Guardian Weekly

If you live outside a major town or city, you belong to a minority of people on the planet. According to the UN, 55% of the world’s population are now urban dwellers, with that figure projected to rise to 68% by 2050. With the world becoming increasingly urbanised, a new wave of megacities – those with populations of 10 million or more – are emerging, and our Big Story this week tells the stories of three such behemoths in the making: Baghdad in Iraq, Dar es Salaam in Tanzania and Xi’an in China.

As the seasonal retail frenzy subsides, economic attention returned to the US-China trade war, which has caused markets to jitter around the world. The two parties returned to the negotiating table this week, but the ramifications of a slowdown in the world’s second-biggest economy will hurt more than just the likes of Apple, which reported a profits slowdown last week. We look at the consequences for workers in the US and China, and for developing nations where China has invested heavily.

The civil war in Yemen that broke out in 2015 caught some by surprise, though its origins had been brewing for years. The overthrow of the US- and Gulf state-backed Yemeni leader Abed Rabbu Mansour Hadi by Houthi rebels quickly deteriorated into a regional proxy war involving Saudi Arabia, Iran and the United Arab Emirates. Almost five years on, Yemen itself is now utterly shattered and, as Ghaith Abdul-Ahad reveals in a visceral long read, the UAE in particular has emerged as the victor from a scene of human and economic devastation.

Brexit returned to the UK headlines this week after some brief seasonal respite, but we pause to reflect on a curious incident that affected Gatwick, the country’s second-busiest airport, just before Christmas. Repeated sightings of drones being flown near the runway caused around a thousand flights to be cancelled or diverted over three days. But weeks later, the police trail has gone cold and some have even questioned whether there really were any drones at all. What lessons can be learned from this bizarre episode, asks the Guardian’s home affairs correspondent Jamie Grierson.

Lastly, good news for dinosaur fanatics in the Washington DC area, as the long-awaited reopening of the Smithsonian museum’s fossil hall nears following refurbishment. Pride of place will go to a giant beastie known as the Nation’s T rex, the 4.5 metre-tall skeleton restored to upstanding glory for the first time in 66m years.