That Sinking Feeling: A Future of Submerged Cities

Sinking Cities: A Future with Rising Oceans

by Ray Grigg - TheCanadian.org

New York may be the environmental story of the year, not because of the 80 fatalities and the $50 billion in damages caused by so-called Superstorm Sandy, but because the city's misfortune has triggered a dawning awareness. In Norfolk, Virginia, where areas of the city of 250,000 now regularly flood from a combination of heavy rain storms and small tidal surges, the local Republican Tea Party activists are the brunt of jokes because they still refuse to use “sea level” and “climate change” in any discussions about their problem. Denial, of course, doesn't change reality. But other low-lying cities along America's coast — Maryland, North Carolina, Florida, and the Gulf and Pacific states — are anxiously watching Norfolk's unfolding misfortune because they are all confronting the same inevitability.

The cause is rising ocean levels. The few millimetres added every year have become a kind of thermometer registering the increase in the planet's temperature. Water expansion, gigatonnes of melting polar and glacial ice, and the billions of cubic metres of irrigation water pumped from aquifers all contribute to the rise. For Norfolk, the only temporary solution to its flooding problem is about $1 billion in dikes, tide gates, elevated roads and powerful pumping stations, all to be built within 30 years — not a pleasant option for a Tea Party that abhors taxes.

Fortunately for Norfolk, it was spared the devastation that befell New York, the latest version of the trauma suffered by New Orleans, and a foreshadowing of events as ocean levels rise and weather becomes more extreme. “We're going to see things like Sandy, where you get complex, extreme events that take us into damages that we've never even imagined could possibly happen,” says Deborah Harford of Simon Fraser University's Adapt to Climate Change Team (The Vancouver Sun, Dec. 8/12).

In the case of New York, 17th in the list of coastal cities at risk, its particular misfortune was a rare combination of an exceptionally high tide, a storm surge and a heavy rain front, precisely the circumstances that could occur in Vancouver and the Lower Mainland. “In an OECD (Organization for Economic Co-operation and Development) report, (Metro) Vancouver is rated 15th (in the world) for exposed assets, with $55 billion at risk, and 32nd in terms of population at risk, with 320,000 people exposed” (Ibid.). Coastal Cities At Risk, another organization studying the threat of rising oceans, predicts that Vancouver would suffer heavy infrastructure damage to “highways, sewer systems, waste treatment facilities, shipping and ferry terminals, and the airport”, and to “farmland and residential and industrial areas” Ibid.).

If the New York disaster seems far away, consider that about 220,000 of the 320,000 of Vancouver's population live at or below sea level, protected by 127 km of dikes that will soon be incapable of fending off a combination of high tides, storm surges and rising sea levels. BC's government is already anticipating a 1.2 metre rise in sea levels in 100 years, an expectation that has doubled since 2009 and seems optimistic given the continuing uncontrolled emission of greenhouse gases worldwide. “If things go really badly,” says Harford, “and our emissions really take off — which quite honestly, they are taking off; we're way above the worst-case scenarios that the Intergovernmental Panel on Climate Change based all its projections on — (the 1.2 metre sea level rise) could happen in 50 years. In the very worst-case scenario it could happen in 20 years” (Ibid.).

Since global temperature increases are already inevitable because of existing and continuing greenhouse gas emissions, ocean levels are going to rise. How much and how fast are the only two uncertainties. Unfortunately, in the past, worse-case scenarios of this kind have always been exceeded by realities.

Many coastal cities seem to have three options to address flooding: plan for an organized retreat to higher ground; elevate key infrastructure such as roads, sewage systems, generating stations, hospitals and homes to allow for regular inundations; or build dikes and other protective mechanisms.

For Vancouver, a recent study found that a necessary protective dike system of 150 km in length and 50 metres wide, with key floodgates at numerous strategic locations, would cost about $9.5 billion. It would have to be built by 2100 or earlier. But it would not stop ,saltwater seepage from contaminating the valuable Delta farmland that presently provides Vancouver with about one-third of its food. Even then, ocean levels would continue to rise, eventually rendering futile such an enormous expenditure of money for just just one city.

Many of the world's most significant cities are coastal, but many less significant ones are also located within the reach of rising ocean levels. And the world is littered with innumerable coastal communities, homes, resorts, infrastructure, and industries that are all potentially threatened. At first, the damage will be inflicted incrementally and irregularly, beginning with unusual combinations of rainfall, storms and tidal surges — more like Norfolk than New York. Then the damage will escalate in frequency, severity and scope. The predicted arrival of a 1.2 metre rise by 2100 is probably a best-case scenario. And the growing instability of Greenland's 3-kilometre-thick ice sheet and Antarctica's glaciers means that dramatic rises could occur relatively quickly. Deborah Harford's “very worst-case scenario” in 20 years is possible, if not probable.

Ocean levels are already rising; this is a fact, not a theoretical prospect. And the Tea Party's denial is not going to stop the process. Refusing to use words such as “sea level” and “climate change” is as futile as trying to stop the arrival of January 1st, 2013.