In making his decision, Indonesian President Joko Widodo said that the move is necessary, given that the city can no longer support its massive population in the face of environmental threats, as well as concerns of traffic congestion and water shortages. Surely at the top of his concerns is the fact that the city is sinking, a phenomenon known as subsidence. In the past 30 years, Jakarta sank more than 10 feet — a problem made only worse as the world’s great ice sheets melt.
Jakarta is an extreme case, but it is by no means unique. In the United States, major cities such as New Orleans and Norfolk are also subsiding, though not nearly as fast. Even still, all coastal cities must face up to the reality of rising seas. There is no time to waste in planning and adapting to this threat.
Although Miami is often cited as the city most at risk, there are many highly vulnerable — and highly populous — cities around the world, including Mumbai and Calcutta, India; Shanghai; Lagos, Nigeria; Manila; Dhaka, Bangladesh; Bangkok; Copenhagen; Tokyo; London; Houston; and Tampa. In fact, thousands of coastal cities and rural communities globally are not only at risk, but already experience increased flooding during extreme high tides, often referred to as “king tides.”
The swelling oceans demand that we start designing for and investing in the future now. The latest projections for average global sea-level rise this century range from about three feet to as much as eight. Keeping it to the lower part of that range largely depends on extreme global efforts to reduce greenhouse gases far beyond current efforts. But even a one-foot rise in sea level can dramatically increase coastal flooding. Hundreds of millions of people and trillions of dollars of assets are at risk.
Indonesia’s decision to be proactive is something all coastal cities should do, what I call “intelligent adaptation.” Instead of spending hundreds of millions of dollars on futile efforts to protect Jakarta from the dozen rivers that run through it — extending fragile walls never engineered to cope with the present threat — it will now start investing in a new capital city that has a sustainable future.
Meanwhile in the United States, the U.S. Army Corps of Engineers recently announced that the combination of rising seas and subsidence will render the $14 billion fix to New Orleans’s levees inadequate in just four years. Clearly, we need a new strategy, too.
Aggressively reducing carbon emissions could avert the worst scenarios, but sea-level rise probably cannot be stopped this century. The planet has already warmed almost 2 degrees Fahrenheit, which means ice sheets and glaciers will continue to melt for centuries.
Engineering for greater “resiliency” — the new buzzword — is a great idea to prepare for short-duration flood events such as from hurricanes. But preparing for rising sea level is different and requires adapting to a new normal.
Though it is tempting to procrastinate, cities would be smart to begin their adaptation planning now. By planning for rising sea levels, cities create confidence in their future. Adaptation can be a tremendous economic opportunity.
Coastal communities should be crafting 30-year master plans to positively address the threat, which could take many forms. For example, Washington is on the Potomac, a tidal river, and already experiences occasional flooding during extreme high tides and stormy weather. Rising seas will make that worse, but the city can probably protect itself with various forms of flood barriers on the river. Most vulnerable cities are not so fortunate and will need to look at a full range of options.
In Jakarta, the solution was to move the capital. Even that dramatic decision will not quickly solve the challenges for the 10 million residents. Yet it recognizes a new reality, allowing them to truly invest in the future. It’s time for all coastal communities to plan for the future.
The sea is rising. We must rise with the tide.