Navigating the Murky Waters of Sea-Level Rise Adaptation

Wednesday, April 6, 2022
Robin Craig headshot

Robert C. Packard Trustee Chair in Law, USC Gould School of Law

The Intergovernmental Panel on Climate Change’s (IPCC’s) latest reports do not bode well. The 2021 Physical Science Report, for example, emphasizes as its primary conclusion that “[i]t is unequivocal that human influence has warmed the atmosphere, ocean, and land.” The global average surface temperature increase since 1850 is about 1.07 degrees Celsius (1.93 degrees Fahrenheit), driven by anthropogenic greenhouse gas emissions. On current trajectories (the IPCC’s “high” and “very high” emissions scenarios), global average temperatures will probably be 3.5 to 4.4 degrees higher than in 1850 by the end of this century, although warming could increase to almost 6 degrees Celsius. Perhaps most disturbing is the fact that three of the five emissions scenarios—the three with the greatest emissions and hence closest to business as usual—do not give the planet any chance of leaving this century at less than 2 degrees warmer than before the Industrial Revolution.

Miami coastline

The ocean is bearing the brunt of climate change so far. It has warmed faster in the last century than at any time in the last 11,000 years. Indeed, “ocean warming accounted for 91% of the heating in the climate system” since 1971, meaning that the ocean has been dampening the impact of climate change on terrestrial life—including most humans.

But the rising, swelling ocean is starting to invade the land. Land-based ice (generally in the form of glaciers) is melting and the ocean is warming, and both processes contribute to sea-level rise. Since 1901, the ocean has risen 0.2 meters, or almost 8 inches, on average globally, although local variations can be far more extreme. For example, in Louisiana, sea-level rise coupled with land subsidence may mean coastal residents see water levels increase by 12 mm, or 0.5 inches, every year. Moreover, “global mean sea level has risen faster since 1900 than over any preceding century in at least the least 3,000 years.” And the pace is accelerating, increasing to 3.7 mm (0.15 inches) per year between 2006 and 2018.

The IPCC’s Impacts, Adaptation, and Vulnerability report, released in February of this year, makes clear that this increasing sea-level rise is a socioeconomic and cultural event. Human settlements along coastlines are particularly vulnerable to medium- and long-term risks from sea-level rise. At a global mean sea level rise of 0.15 meters, about 1 billion people face a 20% increased risk of extreme flooding; with 1.4 meters, that number jumps to 3 billion. Just as importantly, sea-level rise threatens the cultural identity of many coastal peoples, including small island nations and native inhabitants of the Arctic Circle.

Like most coastal nations, the United States must deal with its vulnerability to sea-level rise. While efforts to hold emitters liable play out in courts, adaptation, too, takes a distinctly legal turn. The most obvious issues derive from property law, particularly when governmental adaptation strategies interfere with private property rights. Courts have already begun to wrestle with governments’ attempts to regulate and declare rights to a changing coast.

As early as 2012, for example, the Texas Supreme Court rejected the idea of a “rolling easement” for public use when hurricanes drove its Gulf coast inland, reifying property owners’ constitutional claims. At the same time, sea-level rise increases the stakes in coastal property owners’ desires to install seawalls or other coastal infrastructure to prevent erosion. Because the rising sea is shifting the high tide line, it is also, in many states, moving the line between public and private property. The California Coastal Commission is exploring how these shifts implicate property rights and potentially conflicting state laws.

Beyond property rights, sea-level rise creates many other legal and policy issues. Saltwater intrusion into groundwater is an increasing concern for coastal states from California to Florida, complicating already thorny questions about how to supply clean, safe drinking water in the face of climate change. Land use decisions, including those related to zoning and floodplain ordinances, as well as building codes, are similarly creating a challenging calculus for state and local planners.

Worsening coastal storm damage has also created a number of insurance problems. The National Flood Insurance Program has been in the red financially since the 2005 hurricane season, and Congress now re-authorizes it only for months at a time. The 2005 hurricane season also caused private insurers to leave Florida in droves, a phenomenon that continued well into 2021. Regulating coastal retreat looms large for many communities, but coastal states vary considerably in their flood risk disclosure requirements, leaving buyers—especially along the East Coast—little better off than the common-law caveat emptor.

And then there is public health and safety. Hurricane Katrina and Superstorm Sandy brought with them many lessons about the vulnerabilities of coastal populations, from people stranded in hospitals and nursing homes to the inadequacies of sewage treatment systems. More insidiously, our nation’s coasts are often incredibly toxic places, and saltwater is an excellent solvent. Chemical facilities and other sites that store hazardous waste are likewise vulnerable to sea-level rise and may raise concerns for nearby environmental justice communities. Warming waters also bring with them a number of new diseases, warranting new approaches to public health regulation and training.

In short, sea-level rise in the United States is a multifaceted legal issue. Despite perceptions that adapting to sea-level rise mostly implicates property and land use, it actually requires the creative deployment of many different kinds of legal expertise. Adapting to sea-level rise thus requires a comprehensive legal framework that extends far beyond property rights and land-use planning.

For more information, check out the Legal and Policy Issues of Sea Level Rise episode of People Places Planet podcast where Jarryd Page, a staff attorney at ELI, talks about sea level rise with Robin Kundis Craig.