How would “managed retreat” — moving structures away from the shoreline — work as state policy?

Recent reports from the Intergovernmental Panel on Climate Change remind us that global sea level rise is irreversible, even if we stop greenhouse gas emissions today. Moving away from shorelines is inevitable. But it is a complicated policy question that involves balancing overall public good, private rights, and the particular factors at play along the state’s dynamic coastline.

We have already seen managed retreat in Hawaii. After the repeated tsunamis of 1946 and 1960, folks in Hilo came to better understand the threat of tsunamis and changed their decisions about what to build and where. They essentially mitigated the effects of future tsunamis in their community by relocating away from the coast.

When it comes to sea level rise, the University of Hawaii has a wealth of research that can help guide us into the future. The truth is, sea level rise is such a game-changer that it is probably worth a total rethink of local, state, and national coastal zone policies.

Federal support coupled with state and local government action could put funds toward managed retreat and make a pathway for those dollars to be spent on adaptations to sea level rise. The state and county also could use programs and money to incentivize coastal property owners to voluntarily retreat from the shoreline.

Ideally, we would work with a bundle of economic and policy tools, and they all should emphasize community engagement and public outreach to the affected property owners, but also to the broader community of folks who use and benefit from our public trust beaches.

Which coastal areas risk the greatest loss from sea encroachment?

Certainly areas that are chronically eroding, and our research provides a great roadmap on this question. We have a number of online tools and reports that identify these areas and I would combine this analysis with our projections of future erosion as well. The best tools for Hawaii include the NOAA SLR Viewer, NOAA Flood Exposure Mapper, and the Hawaii SLR Viewer.

Groundwater inundation and storm drain backflow are often ignored because they are less visible, but are crucial to consider. In short, many of our coastal areas are going to become wetlands as the water table rises in parallel with sea level rise. You can see this in certain urban areas where the storm drain system, designed to carry away runoff using gravity, is instead acting as a source of saltwater flooding during high tide.

What is the state’s responsibility in responding to private property collapse, as has happened recently on the North Shore?

Under the public trust doctrine the state has a legal responsibility to maintain beaches for citizens of the state and its future generations. Key to this is the recognition that sea level rise is not a threat to beaches because under natural conditions, they respond by migrating landward, driven by a combination of rising water and wave energy.

However, seawalls, revetments, sandbags and other measures prevent this natural response and eventually destroy the beach. Recent amendments to state law preventing shoreline hardening on sandy beaches have sent a strong message that the government intends to conserve Hawaii’s beaches.

Beyond that, the state has no responsibility to protect private property from coastal erosion, but should be using its power and funds to incentivize coastal property owners to move away from the shoreline. Proactive regulation and enforcement of our existing shoreline regulatory regime are necessary to prevent situations like the one at Rocky Point.

Is it too late for carbon emission reduction to ward off serious coastal damage?

Yes, it is obviously too late. Look at the threatened homes on Sunset Beach. These homeowners and the state and county would describe this as “serious coastal damage.”

Now we need to take action to limit this problem. The most recent IPCC Report tells us that a planetary emergency exists. Greenhouse gas emissions need to peak by 2025, decline 40-50% by the end of the decade, and reach net zero by mid-century. However, instead of declining, on track with global energy policies, emissions are projected to increase 7-15% by the end of the decade.

With continued greenhouse gas emissions we risk pushing large-scale global systems such as permafrost, Arctic sea ice, ocean circulation, tropical and boreal forests, coral reefs, marine ecosystems and massive ice sheets past the point of no return.

Are there any advances or innovations that give you hope for solutions?

In some aspects, hope is our biggest enemy. We aren’t going to manage this problem with hope. But giving up, or taking a pessimistic approach, won’t help either. We must remain optimistic, and optimism is embedded in action.

Here are just five:

1. Building a zero-emissions electric grid.

2. Decommissioning existing fossil-fuel infrastructure and keeping unused oil, gas and coal reserves in the ground.

3. Transportation must become emissions-free.

4. Buildings must be zero emissions. By 2030, one-third to half of all buildings need energy and efficiency retrofits.

5. An agriculture revolution must take place. Producing beef generates 100 times more greenhouse gas than plant-based food, and eating beef is unhealthy. Sustainable food production includes steps to increase soil carbon storage.

Every part of society must experience transformational change – nobody, no sector, can sit this one out.

THE BIO FILE

>> Title: Interim dean, School of Ocean and Earth Science and Technology, University of Hawaii-Manoa.

>> Professional: Joined UH-Manoa in 1991, served as professor, department chair, associate dean, interim dean.

>> Community: Formerly on Kailua Neighborhood Board, Legacy Land Conservation Commission, currently chair of the Honolulu Climate Change Commission.

>> Family: Wife Ruth, president of St. Andrews Schools; three adult children, two sons-in-law, two grandchildren.

>> One more thing: Climate change threatens Hawaii supply lines. To thrive, we need to unify the community and accelerate local food production, electricity and fuel independence, and climate-resilient development.