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Why Study King Tides?

Documenting King Tides helps researchers, decision makers, and communities better understand and prepare for sea level rise. 

We know that global mean sea level is rising at an exponential rate. Pacific Island communities are especially vulnerable to the impacts of sea level rise because so many of our homes, businesses, agriculture lands, cultural and historic sites, and important ecosystems are located in low-lying coastal areas. King Tides (the highest high tides of the year) provide a glimpse into the future of what our shorelines may look like on a more regular basis as a result of rising sea levels.

Sea Level Rise

Sea levels have been rising at an increasing rate over the last century. In the early 1900s global mean sea level was rising at a rate of about 3 in/century today that rate has accelerated to 1.5 ft/century and continues to speed up.


Hawaiʻi and Pacific Islands King Tides Project

Graph showing accelerated pace of Global Mean Sea Level rise over last 100 years
Across the globe the rate of sea level rise is accelerating over time. (Church and White 2011, Nerem et al. 2010, Yi et al. 2015, Hay et al. 2015, Hansen et al. 2016, Watson et al. 2015, Fasullo, Nerem, and Hamlington 2016)

“Given what we know now about how the ocean expands as it warms and how ice sheets and glaciers are adding water to the seas, it’s pretty certain we are locked into at least three feet of sea level rise, and probably more…but we don’t know whether it will happen in 100 years or 200 years.” – Steve Nerem, NASA Sea Level Change Team Lead, 2015

The future pace of sea level rise depends on how much greenhouse gas pollution we as a global community continue to emit. A 2017 NOAA Technical Report projects global mean sea level rise of 3 feet by 2100 under an intermediate scenario and 6 to 8 feet under an extreme scenario. The 2017 Hawaiʻi Sea Level Rise Vulnerability and Adaptation Report recommended using 1 foot of sea level rise for short-term decision making (decisions with implications in the next 30 years) and 3 feet of sea level rise for mid-term decision making (decisions with implications extending more than 30 years into the future). Sea level rise will exacerbate existing coastal hazards across Hawai‘i and Pacific Islands including erosion, coastal flooding, saltwater intrusion, and damage from storm surge.

Graph showing six sea level rise projections in meters out to the year 2100.
Global and Regional Sea Level Rise Scenarios for the United States, 2017. NOAA Technical Report NOS CO-OPS 083
A Community Science Approach

The Hawai‘i and Pacific Islands King Tides Project uses a comunity science approach that allows the project to cover a wide geographic area spanning across the Pacific Region and to tap into the place-based and local knowledge of communities and residents with deep personal connections to and knowledge of coastal areas.

Key components of Community Science:

  • Anyone can participate
  • Many hands make light work
  • Consistent protocol and methods
  • Publicly accessible data
  • Addresses real-world issues important to communities
Applying Community Science Data in Research and Policy Decisions

Hundreds of Community Scientists from across the Pacific Region have contributed thousands of photo records to the Hawai‘i and Pacific Islands King Tides Project. These records are stored in a publicly accessible online database and serve as a critical resource for researchers, policy makers, and community members to better understand the potential impacts of sea level rise and other coastal hazards. Photographs from the Hawai‘i and Pacific Islands King Tides Project have been featured in the 2017 Hawaiʻi Sea Level Rise Vulnerability and Adaptation Report and have been used to help ground truth sea level rise models simulating groundwater inundation in Honolulu.