The future of sustainable development will hinge on the fate of cities as more than half of the world's population now live in urban environments, a number likely to rise to nearly 70 percent by 2050, according to the UN officials.

"The actions we take now must lead us to…a new social integration based on the principles of prosperity, transformation, adaptation, equity and respect for human rights," said Martha Delgado, president of the UN-Habitat Assembly Thursday.

Highlighting urbanisation as one of today's great megatrends, she called for resilient, sustainable "smart cities" that are more inclusively governed and better prepared to navigate future shocks and crises.

"Sustainable development will hinge on how we manage urbanisation," Economic and Social Council President Collen Vixen Kelapile said, adding that current discussions should be framed in the context of responding to Covid response and the climate crisis.

Around 1.2 billion people in the global South now live in informal settlements and slums and they have long struggled to prevent disease transmissions, now including Covid, Collen added.

In the global North, dependence on welfare, where available, increased manifold during the pandemic and many people entered the ranks of the homeless.

In response, cities have deployed creative actions and provided services in underserved areas, while new urban models are beginning to pay more attention to pedestrians and mixed land uses.

"The world's cities have been absorbing much of Covid's socio-economic impact," UN-Habitat chief Maimunah Mohd Sharif said.  

"However, that has often resulted in closer cooperation between national and local governments, which, in turn, has led to greater reclamation, greening and inclusive use of public space."

"Cities can spearhead innovations to bridge the inequalities gaps, deliver climate action and ensure a green and inclusive Covid recovery," said Amina Mohammed, deputy secretary-general of the UN and chair of the UN Sustainable Development Group.

"Urban spaces connect the dots on many of today's global challenges."