Climate Migration: New Cities on Higher Ground

janvier 24, 2020 — The Big Picture

Making cities safer is our challenge. In the past, cities destroyed by fire or in war were rebuilt, often to a higher standard of construction and with the most modern infrastructure. Catastrophes come without warning, and catch people unprepared. The trends of climate change, and its effects, call for action. But tragic events that could occur in two or three decades however give us time to procrastinate; plans to build sea walls may give people a false sense of security; when disasters only happen elsewhere, people become complacent. How will cities be rebuilt to reduce carbon emissions? Can coastal cities be protected from rising sea levels? What if some cities may no longer be inhabitable? Each question poses different challenges.

Already 100 million people live on land below sea level; 250 million are exposed to annual floods related to storms. A billion people live no higher than ten meters above sea level. These numbers of people at risk are adjusted upwards with every increase in the possible rise in the level of the sea. The estimates for the Netherlands are 5.6 million people, the United Kingdom, 3.6 million, and France, 1 million. Property owners often oppose measures to prevent construction in areas subject to recurrent flooding. These estimates, based on the current size and distribution of coastal zones, may be too low. Are we willing to expose a million people to risks, but not, say, two million? What is the threshold at which action becomes imperative?

There is an economic argument to protect coastal cities. But more frequent disasters at more frequent intervals which quite literally erode property values will undermine the cost-benefit argument for investment in expensive engineering works. (OECD, 2019). Flood insurance may give rise to moral hazards because people under-invest in protecting their property; the same risk arises if people believe that the state will bail them out. In the long term we all pay by doing too little, too late.

Urbanization has been most rapid in recent decades in Asia where the orders of magnitude are qualitatively different from Europe. The number of people living in flood plains in Asia may well double by 2060. Already by 2050, three times more Chinese – nearly 100 million -will be exposed to annual floods than had been forecast only a few years ago. The figure for Bangladesh is 43 million, India, 36 million for Vietnam, 31 million, Indonesia, 24 million. Of the 20 cities exposed to the greatest loss by annual flooding by 2050, 13 are in Asia. Singapore, a city-state that has a limited territory, is hoping to retain water by natural means, expanding swamps, canals and lakes. Jakarta, 40% of which is below sea level, was flooded under 4 meters of water in 2007, again in 2013 and most recently in December 2019. A $40 billion project to protect Jakarta Bay with a sea wall and artificial islands has been scaled back; the government is planning to build a new capital city, the strategy of planned relocation.

What then if people panic and take flight? That is precisely what happens when governments are not trusted. Three examples: people moved away from the centre of Mexico City after the 1985 earthquake; although two earthquakes in 1999 spared Istanbul, people relocated within that city, knowing that many buildings were unsafe but were unsure which ones were on solid ground, a clear example of how a disaster in one place can affect behavior in another; Hurricane Katrina destroyed or severely damaged 217,000 houses in 2005; a year later barely 50% of displaced households had returned to the city. Large numbers no longer shock. Remember the tsunami of 30 meter-high waves on 26 December 2004 that occurred after the 3rd largest earthquake ever recorded? Some 228,000 people in 14 countries died.

Relocation may be unavoidable in some cases when engineering is either too expensive or simply infeasible. An organized retreat away from the coast can be encouraged by governments through planned developments, subsidies and fiscal incentives, even expropriation. The up-front costs are high and immediate.

What happens if a major disaster occurs first, and governments have to decide in days or weeks whether or not to rebuild? Much will fall upon regional and local governments which themselves face barriers: constitutional limitations on what they can do; excessive administrative fragmentation; restructure regulatory agencies with overlapping or incomplete responsibilities; responsibilities that exceed resources; weak planning capacity at local level. “In the rich world such ‘managed retreat’ is anathema…Relocating a neighbourhood in New York requires the consent of the residents; holdouts can block decisions for years”. Of course! How else to prevent the government from acting arbitrarily? [The Economist, 2019, p. 18] Preparing a new city is hard enough, but organizing the abandonment of an old one at the same time would be extremely difficult to do in a democratic society at peace.

Relocation to existing or to new cities is the “orphan child” in the story of climate change, an embarrassment because we do not know what to do about it. More questions than answers; empirical studies based on disaster history may be an imperfect guide for policy-makers, and the vast majority of people will in any case remain ill-informed. What do we know about planned new cities in postwar America? Western and Eastern Europe? China? Southeast Asia? Perhaps, as average temperatures and sea levels rise in Florida or around the Mediterranean, people will relocate on their own in search of pleasanter climes. An internal migration of a hundred million Americans however would cause the construction of a dozen cities the size of New York, an effort which itself will increase carbon emissions.

Mankind, ever resilient, is again on the move. Before the Great War, millions emigrated from Europe and Asia to build cities on the frontier in Canada, the United States, Australia. Border changes in Europe after each world war, the Great Depression in the interwar era, and decolonization in the 1950s and 1960s saw millions of people on foot, or in overcrowded ships and railroad carriages. These human floods changed the landscape of the world, and will do so again when millions will resettle away from seacoasts prone to savage storms, flooding, or total submersion. How can the design of new cities help to make relocation an attractive option?

For further reading:

“The Rising Seas”, 17 August 2019, pp. 15-19, McHarg Center for Urbanism and Ecology, The 2100 Project: An Atlas for a Green New Deal (Philadelphia: Weitzman School of Design, University of Pennsylvania, 2019)

Organisation for Economic Co-operation and Development, Responding to Rising Seas: OECD Country Approaches to Tackling Coastal Risks, 2019; case studies of the German Baltic Seacoast, Nova Scotia, New Zealand and the United Kingdom.

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