Ocean Acidification
Preserving the Chemistry of Life
Overview
Ocean Acidification (OA) is often called the “other carbon problem”. As the ocean
absorbs approximately 30% of the carbon dioxide (CO2) released into the atmosphere,
its chemistry changes, becoming more acidic. This process lowers the pH of seawater
and reduces the availability of carbonate ions, which are the building blocks for marine
life.
In Hawaiʻi, this invisible crisis threatens the very foundation of our marine ecosystems. Calcifying organisms – including coral polyps, shellfish, urchins, and coralline algae – struggle to build their skeletons and shells in acidic waters. Without healthy coral reefs
to buffer waves and provide habitat, the state faces cascading risks to coastal
protection, food security, and the marine economy.
Numbers and Targets
Key Targets:
- State Action Plan: Implement the 5 goals of the Hawaiʻi Ocean Acidification Action Plan 2021-2031 to science, mitigation, adaptation, and policy.
- Monitoring Network: Formalize and expand the Hawaiʻi Ocean Acidification Monitoring Network to track pH changes across the islands.
- Pollution Reduction: Reduce land-based sources of pollution (like sediment and nutrients) which can locally exacerbate acidification.
Impact Profile:
- Rate of Change: Ocean acidity has already increased by 30% globally since the industrial revolution and could double by 2100.
- Bleaching Events: Rising sea surface temperatures and acidification are increasing the frequency of coral bleaching; a notable event in 2014 saw 80% of dominant corals in Kāneʻohe Bay experience bleaching.
- Economic Risk: Reef loss due to acidification and warming is projected to cause up to $2.1-3.3 billion in losses to the recreational value of Hawaiʻi's reefs by 2100.
Key Features of Hawaiʻi's Ocean Acidification Sector
The State Action Plan (2021-2031)
Hawaiʻi was one of the first jurisdictions to develop a dedicated Ocean Acidification
Action Plan. This strategic document coordinates efforts between state agencies,
researchers, and federal partners to bridge the gap between global carbon emissions
and local marine management.
The Coastal pH Monitoring Network
Unlike the open ocean, coastal chemistry is highly variable. Hawaiʻi leverages a network
of buoys and sensors, managed by partners like PacIOOS and UH Mānoa, to monitor
real-time changes in acidity. This data is critical for identifying local “hotspots” where
land-based pollution worsens acidification.
Vulnerability Assessments
International Leadership
As a member of the International Alliance to Combat Ocean Acidification, Hawaiʻi joins a
global coalition of governments committed to local action. This partnership allows the
state to share best practices and elevate island voices on the global stage.
Challenges and Opportunities
Challenges
- Invisible Threat: Unlike plastic pollution or erosion, OA is invisible to the naked eye, making public engagement and policy urgency difficult to generate.
- Global vs. Local: While the primary driver (atmospheric CO2) is global, local stressors like nutrient runoff can lower coastal pH further, requiring complex, multi-scale management
- Ecosystem Collapse: If acidification outpaces the ability of corals to calcify, reef structures could begin to dissolve, leading to a loss of habitat for fish and reduced shoreline protection.
Opportunities
- Nature-Based Buffers: Restoring seagrass beds and limu (seaweed) can locally raise pH levels through photosynthesis, creating “halos” of better water quality for nearby corals
- Biocultural Restoration: The restoration of loko i‘a (traditional fishponds) and wetlands is highlighted as a strategy to filter sediment and improve coastal water quality, creating healthier environments for marine life.
State and County Actions
State of Hawaiʻi
University of Hawaiʻi
UH Mānoa and SOEST are global leaders in OA research, running the Hawaiʻi Ocean Time-series (HOT) which provides the long-term data proving ocean chemistry is changing.
County Actions
Measure Description and Scope
| Measure | Description | Measure Scope |
|---|---|---|
| OA-1. Scientific Understanding | Expand monitoring and research capacity | Monitoring: Maintain and expand the buoy
network (e.g., PacIOOS) to track pH trends. Research: Study the resilience of native species to lower pH levels. |
| OA-2. Mitigation (Local) | Reduce stressors that worsen acidification. | Pollution Control: Mitigate land-based
nutrients (cesspools, fertilizer) that trigger algal
blooms and lower pH.
Nature-Based Solutions: Restore limu and seagrasses to absorb CO2 locally. |
| OA-3. Adaptation & Resilience | Build community and ecosystem resilience. | Vulnerability:Conduct risk assessments for
coastal communities reliant on reefs.
Restoration: Select resilient coral strains for out-planting efforts |
| OA-4. Public Engagement | Raise awareness of the “invisible crisis.” | Education: : Integrate OA curriculum into
schools and community outreach programs to
link carbon emissions to reef health.
|
Case Studies
Hawaiʻi Ocean Acidification Action Plan (2021-2031)
PacIOOS Water Quality Buoys
The Pacific Islands Ocean Observing System (PacIOOS) manages a network of sensors that provide real-time data on ocean acidity (CO2 and pH). These buoys, located at key sites like Kāneʻohe Bay and the south shore of Oʻahu, provide the essential baseline data needed to distinguish between natural cycles and human caused acidification.
UH Socioeconomic ulnerability Study
Researchers at UH Mānoa combined oceanographic models with economic data to project the financial impact of OA on Hawaiʻi. They found that different islands face different risks for example, reefs in Kona are projected to degrade faster than those in Hilo—providing critical data for prioritizing management resources.
Further Actions
For Individuals
- Reduce Carbon: The most effective way to stop acidification is to lower your carbon footprint; walk, bike, or use public transit.
- Reduce Runoff: Use phosphate-free detergents and minimize fertilizer use in your garden to prevent nutrient runoff that worsens local acidity.
- Support Science: Participate in citizen science projects that monitor water quality or reef health.
For Businesses
- Carbon Neutrality: Commit to carbon neutrality in operations to address the root cause of acidification.
- Sustainable Siting: Ensure coastal developments manage stormwater on-site to prevent nutrient loading into the ocean.
For NGOs
- Education: Translate complex chemical concepts into accessible stories about the future of seafood and cultural resources.
- Restoration: Partner on projects that restore calcifying organisms (like oysters or corals) and pH-buffering plants (seagrass).
Resources
State Agencies
- DLNR Division of Aquatic Resources (DAR) – https://dlnr.hawaii.gov/dar/
The lead agency for the State OA Action Plan and marine management.
Educational Resources and Programs
- PacIOOS (Pacific Islands Ocean Observing System) – https://www.pacioos.hawaii. edu/ Provides real-time ocean data, including acidity levels, for the Pacific region.
- UH SOEST Department of Oceanography https://www.soest.hawaii. edu/oceanography/ Conducts world-class research on ocean chemistry and the carbon cycle.
Policy and Advocacy
- International Alliance to Combat Ocean Acidification – https://www.oaalliance.org/
A global partnership of governments, including Hawaiʻi, working to address OA.
- NOAA Ocean Acidification Program – https://oceanacidification .noaa.gov/ Federal program providing funding, research, and monitoring support.
Non-Profit Organizations
- Sustainable Tourism Association of Hawaiʻi (STAH) https://www.sustainable tourismhawaii.org/ Promotes the “Travel Pono” program and certifies sustainable tour operators.