Cities and populations that will be most affected by sea level rise in a world that's 3C warmer than the pre-industrial global average surface temperature. Graphic: The Guardian

By Josh Holder, Niko Kommenda, and Jonathan Watts
3 November 2017(The Guardian) – When UN climate negotiators meet for summit talks this month, there will be a new figure on the table: 3C.
Until now, global efforts such as the Paris climate agreement have tried to limit global warming to 2C above pre-industrial levels. However, with latest projections pointing to an increase of 3.2C by 2100, these goals seem to be slipping out of reach.
“[We] still find ourselves in a situation where we are not doing nearly enough to save hundreds of millions of people from a miserable future,” said Erik Solheim, the UN environment chief, ahead of the upcoming Bonn conference.
One of the biggest resulting threats to cities around the world is sea-level rise, caused by the expansion of water at higher temperatures and melting ice sheets on the north and south poles.
Scientists at the non-profit organisation Climate Central estimate that 275 million people worldwide live in areas that will eventually be flooded at 3C of global warming.

Asian cities will be worst affected

The regional impact of these changes is highly uneven, with four out of five people affected living in Asia.Although sea levels will not rise instantaneously, the calculated increases will be “locked in” at a temperature rise of 3C, meaning they will be irreversible even if warming eventually slows down. […]

Shanghai, China

17.5 million people affected“Shanghai is completely gone – I’d have to move to Tibet!” says resident Wang Liubin, when he is shown projections for the city after 3C of global warming.When it comes to flooding, the coastal city is one of the world’s most vulnerable. Now one of the world’s biggest ports, the former fishing village is bordered by the Yangtze river in the north and divided through the middle by the Huangpu river; the municipality involves several islands, two long coastlines, shipping ports, and miles of canals, rivers, and waterways.

Projected flooding in Shanghai, China due to sea level rise in a world that's 3C warmer than the pre-industrial global average surface temperature. Graphic: The Guardian

In 2012, a report from a team of UK and Dutch scientists declared Shanghai the most vulnerable major city in the world to serious flooding, based on factors such as numbers of people living close to the coastline, time needed to recover from flooding, and measures to prevent floodwater. According to Climate Central projections, 17.5 million people could be displaced by rising waters if global temperatures increase by 3C. [more]

The three-degree world: the cities that will be drowned by global warming