Warmer air temperatures are causing our oceans to thermally expand and glaciers around the world to melt. This combination leads to global sea level rise, which is accelerating and expected to reach over 3 feet (1 meter) by the end of the century, with a 10% chance of exceeding 6.5 feet (2 meters).

In fact, the last time it was this warm was about 125,000 years ago when sea level was 20 feet (6 meters) higher.

Sea level rise threatens the continued existence of coastal communities and ecosystems. Globally, land that is currently home to 300 million people will flood at least once a year by 2050, and as many as 640 million people could be threatened by 2100.

Among Pacific islands, salt water already washes over low-lying atoll communities ruining freshwater aquifers, critical agroforestries, and flooding roads and buildings. Sovereign nations with rich cultural heritages such as the Marshall Islands, Kiribati, and others have declared that leaving their ancestral homelands threatens their very identity.

Given the reality that sea level rise is accelerating and very likely to rise several feet more, the future of these low-lying islands is at the forefront of climate change conversations.

Government Response

In Hawaii, all levels of government have begun planning for sea level rise and other impacts of climate change. A number of important policies are under revision including building restrictions along the coast, permit conditions in areas exposed to future sea level rise flooding, and new design requirements for public infrastructure projects.

The Honolulu Climate Change Commission has issued guidance for adapting to sea level rise:

  • Plan for at least 3.2 feet of sea level rise by the end of the century;
  • for large projects that have low tolerance for risk, plan for 6 feet of sea level rise; and
  • the zone exposed to 3.2 feet of sea level rise is already experiencing high tide flooding. The severity of this will accelerate strongly over the next two to three decades and beyond.

Many public and private construction projects in Honolulu are including features to mitigate flooding related to sea level rise: Elevated rail between Chinatown and Ala Moana Center has been redesigned to accommodate 6 feet of sea level rise, transit-oriented development at future rail stations incorporates flood-proofing for higher sea level, and a major hotel in Waikiki is raising its ground floor 8 feet to avoid flooding from the sea.

King tides flooded Ahua Street in Mapunapuna in May 2017. Much of Hawaii’s population and industry are located in low-lying areas vulnerable to sea level rise.

Anthony Quintano/Civil Beat

There are many examples of sea level rise adaptation emerging in our communities.

The City and County of Honolulu Office of Climate Change, Sustainability and Resiliency is coordinating actions and policies of departments within the city to increase community preparedness, developing resilient infrastructure in response to the effects from climate change, and integrating sustainable and environmental values into city plans, programs and policies.

The Hawaii Climate Change Mitigation and Adaptation Commission was created by Act 32 in 2017. It meets quarterly and is dedicated to promoting ambitious, climate-neutral, culturally responsive strategies for climate change adaptation and mitigation in a manner that is clear, equitable and resilient.

King Tides

In Honolulu, flooding caused by sea level rise is already occurring in the form of high tide flooding. In 2017 Kakaako, Waikiki, and other low-lying coastal locations experienced the highest water levels in the 112-year record of the Honolulu tide station. These received widespread media attention and became known as king tides.

Today, king tides occur during perigean spring tides, new and full moon phases in summer and winter months causing the highest tides of the year. A perigean spring tide turns into a king tide when the water level is higher than predicted. This can occur with unusually warm sea surface temperatures (such as the recent marine heat wave), winds that raise the water level, and when-eddy-like circulation features (known as meso-scale eddies) develop in Hawaiian waters.

Communities should take note of sea level rise when flooding is seen in unexpected areas. Examples include waves that reach onto roads and into buildings, wetlands flooded with standing water during a dry period, storm drains that fill with seawater and spill out onto the road (storm-drain back flow), and water that seeps into basements and garages.

Seawater enters communities in three ways during king tide floods: 1) direct seawater flow across the shoreline (perhaps driven by waves, but in the case of the Ala Wai canal not necessarily), 2) groundwater inundation when the water table floods up through the ground surface, and 3) storm-drain back flow.

The first time these are noticed they may be ignored. But these are the early signals of sea level rise.

Convergence Of Events

In Honolulu, king tides occur late in the day during summer months, exactly when families are commuting home. When it rains during a king tide in an urban setting, there is nowhere for the runoff to go. Storm drains are blocked by high tide, the ground is saturated by the high water table, and water collects in knee-deep (even waist-deep) floods on roads. This shuts down roads and snarls traffic.

As global warming makes homes hotter and hotter, power utilities are seeing a growing demand for electricity at the end of the work day as families turn on air conditioners, lights, washing machines, and more. In recent years, public service announcements have been issued asking that customers conserve power to avoid a blackout. These have been seen during the hottest days of August and September.

A child plays near an under-construction sea wall in Majuro, the capital of the Marshall Islands, November 2018.

Jessica Terrell/Civil Beat

A power blackout at this time shuts down traffic signals, pumps, street lighting and lights at parking lots and workplaces. This convergence of events — a king tide, rain, separated family members, snarled traffic, and blackouts — are among the unanticipated impacts of global warming in an urban setting.

These events are going to increase in frequency and magnitude over the next two to three decades. Research at the University of Hawaii Sea Level Center found that in Honolulu, more than 100 days of king tide flooding is possible during the worst year of the 2030s and the frequency of flooding quadruples from 50 to 200 days per year on average from the 2030s to the 2040s. Researchers have also found that strong El Niño events, when intense rainfall is more common, are going to occur more often with global warming.

Social Justice

In the midst of these events, it is important to keep in mind the larger picture: to think about the impact that sea level rise is having on other islands across the Pacific as well.

More than a technical traffic and power challenge, at the core of this scene lies a social justice problem.

As we adapt, we must build social repair into every effort.

In Hawaii, the resources exist to support a fair and equitable community and environment. However, unaffordable housing, a massive service industry focused on tourism, and intense wealth stratification mean that the largest portion of our population lives from paycheck to paycheck, endures long commutes from underserved communities, and has few opportunities to significantly grow their income.

Native Hawaiians constitute a disproportionate percentage of this population and the wounds of their stolen kingdom are still raw. While the daily joys of life here are immense, the rising frequency of unexpected weather shocks and the daily grind of traffic woes wear at the fabric of our community.

As we adapt to sea level rise and rising heat, we must build social repair into every effort.

Government that attends to social repair can lead the way with demonstration projects, and by implementing policies and guidelines that mitigate the effects of climate change.

To learn more about the importance of integrating culture and community into climate change discussions, join us for events related to “Inundation: Art and Climate Change in the Pacific” at the University of Hawaii-Manoa Art Gallery (Jan. 19 through Feb. 28), or at Donkey Mill Art Center in Kona (March 28 through June 26).

Details about opening performances, public talk stories, and community art projects are at www.inundation.org.

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