What is the Cost of One Meter of Sea Level Rise?

Research Assistant Professor of Civil & Materials Engineering

The opening line of our recent Scientific Reports article reads “Global climate change drives sea level rise, increasing the frequency of coastal flooding.” Some may read this as plain fact. Others may not.

Undeniable and accelerating

100 years of data from tide gauges and more recently from satellites has demonstrated an unequivocal rise in global sea level (~8-10 inches in the past century). Although regional sea level varies on a multitude of time scales due to oceanographic processes like El Niño and vertical land motion (e.g., land subsidence or uplift), the overall trend of rising sea levels is both undeniable and accelerating. Nevertheless, variability breeds doubt. Saying that global warming is a hoax because it’s cold outside is like saying sea level rise doesn’t exist because it’s low tide.

Global sea level is currently rising at 3–4 mm/year, making it a relatively slow process. For instance, tides typically change sea level by 0.5-1.0 m every 12 hours, a rate that is ~100,000 times faster than global mean sea level rise.

It’s almost as if sea-level rise were slow enough for us to do something about it…

The civil engineering challenge of the 21st century

At the end of a recent news article by New Scientist, Anders Levermann, a climate scientist for the Potsdam Institute for Climate Impact Research, said “No one has to be afraid of sea level rise, if you’re not stupid. It’s low enough that we can respond. It’s nothing to be surprised about, unless you have an administration that says it’s not happening. Then you have to be afraid, because it’s a serious danger.”

Levermann’s quote captures the challenge of sounding the whistle on the dangers of climate change. We know that sea level rise is a problem; we know what’s causing it (increased concentrations of heat-trapping gasses like CO₂ leading to the thermal expansion of sea water and the melting of land-based ice); we know how to solve the problem (reduce carbon emissions and cap global temperatures); yet, in spite of the warnings, the current administration recently chose to back out of a global initiative to address the problem.

Arguing that the Paris agreement is “unfair” to the American economy to the exclusive benefit of other countries is extremely shortsighted. This perspective serves to kick the climate-change can down the road for the next generation to pick up. This perspective, if it dominates US decision making moving forward, sets us up for the worst-case scenarios of sea-level rise (more than two meters by 2100). Worse yet, this perspective may take us beyond the time horizon in which a straightforward solution may be found, leaving geoengineering solutions as our last-and-only resort.

If the Paris agreement is unfair to the American economy, imagine about how unfair 2.0+ m of sea-level rise would be. We should seriously question the administration’s focus on improving national infrastructure without considering arguably the greatest threat to it. Sea-level rise will be one of, if not THE greatest civil engineering challenge of the 21^st century.

Sea level rise will:

An astronomically high dollar figure

As a thought experiment, try to quantify the economic value of one meter of sea level rise. Low-lying coastal regions support 30% of the global population and, most likely, a comparable percentage of the global economy. Even if each meter of sea level rise only affected a small percentage of this wealth and economic productivity, it would still represent an astronomically high dollar figure.

Although managed retreat from the coastline is considered a viable option for climate change adaptation, I don’t see a realistic option where we relocate major coastal cities such as New York City, Boston, New Orleans, Miami, Seattle, San Francisco, or Los Angeles.

What will convince the powers-that-be that unabated sea level rise is an unacceptable outcome of climate change? Historically, the answer to this question is disasters of epic proportions.

Hurricane Sandy precipitated large-scale adaptation planning efforts in New York City. Nuisance flooding in Miami has led to a number of on-going infrastructure improvements. The Dutch coast is being engineered to withstand once-in-10,000-year storms. Fortunately, most nations and US states, particular coastal states like Hawaii and California, will abide the Paris agreement.

This administration doesn’t seem to care about the science of climate change, but it does seem to care about economic winners and losers. Would quantifying the impacts of climate change in terms of American jobs and taxpayer dollars convince the administration to change their view of the Paris agreement?

Impossible to ignore

In the executive summary of the 2014 Risky Business report, Michael Bloomberg writes, “With the oceans rising and the climate changing, the Risky Business report details the costs of inaction in ways that are easy to understand in dollars and cents—and impossible to ignore.” This report finds that the clearest and most economically significant risks of climate change include:

Climate-driven changes in agricultural production and energy demand
The impact of higher temperatures on labor productivity and public health
Damage to coastal property and infrastructure from rising sea levels and increased storm surge

For example, the report finds that in the US by 2050 more than $106 billion worth of existing coastal property could be below sea level. Furthermore, a study in Nature Climate Change found that future flood losses in major coastal cities around the world may exceed $1 trillion dollars per year as a consequence of sea level rise by 2050.

The science and economics of climate change are clear.

So why do politicians keep telling us that it’s not happening and that doing something about it would be bad for the economy?