New Tool Identifies Carbon Hotspots in Oregon’s Largest Estuary

Coastal habitats, including tidally influenced wetlands and seagrasses, are incredibly efficient at capturing and storing carbon dioxide from the air and surrounding waters. These carbon stores—known as blue carbon because they are located in waterlogged places where land meets the sea—can remain locked away for hundreds or even thousands of years. When coastal habitats are destroyed or degraded, however, their carbon stores are released back into the atmosphere.

Over the past 150 years, Oregon lost significant amounts of coastal wetland habitats due to land use practices that diked and drained these areas for farming and development. Before the state had wetland protection policies in place, dikes and levees were built to restrict tidal flow. Without normal tidal flow to keep them wet, these areas would seasonally dry out and release stored carbon.

The need for spatial data

Fortunately, Oregon is now taking steps to protect remaining coastal wetlands from further loss and, where feasible, to restore diked agricultural lands. State leaders recognize that in addition to storing carbon, wetlands offer many other benefits, including providing habitats for salmon and other fish, and protecting communities from flooding. Because of the increased interest in the climate benefits that coastal wetlands provide, Oregon’s Coastal Management Program partnered with experts to develop a greenhouse gas inventory that estimates carbon sequestration rates in these habitats.

In 2023, Oregon Governor Tina Kotek signed into law the Climate Resilience Package, which calls for the conservation and restoration of blue carbon habitats as a pathway for advancing Oregon’s climate goals. It also establishes a natural climate solutions fund to advance strategies such as coastal wetland restoration.

With increased state and federal focus and funding for nature-based strategies that help mitigate climate change, there is a need for high-quality spatial data to identify areas where protection and restoration would result in blue carbon benefits. To fill this gap, a Pew-supported technical team composed of the nonprofit Institute for Applied Ecology and consulting firms Sea & Shore Solutions and Silvestrum Climate Associates has created a tool that enables different audiences to view and use data for planning blue carbon conservation and restoration initiatives. The pilot version of the tool focuses on the Coos Estuary, Oregon’s largest estuary entirely within state lines, which encompasses approximately 20 square miles.

How the mapping tool was developed

The tool is built using the National Oceanic and Atmospheric Administration’s Coastal and Marine Ecological Classification Standard (CMECS), a national framework for describing and classifying coastal and marine ecological data. The team refined the original CMECS data for the Coos Estuary through site visits and detailed analysis of elevation data. With help from local experts, the team refined the original CMECS mapping of potential restoration areas by verifying locations of dikes and other manmade structures that limited tidal flow.

The elevation data was then used to determine the potential post-restoration habitat types for each site, such as forested tidal wetlands or scrub-shrub tidal wetlands. For each of these habitats, researchers applied blue carbon values derived from the state-level greenhouse gas inventory. Lastly, this data was brought into an online mapping tool, which is designed for ease of use by anyone from beginners to geographic information system, or GIS, experts. Experts can also use the tool to download raw data for analysis within their own software systems.

The tool is available at Oregon Explorer, a natural resources digital library. It illustrates blue carbon values in the Coos Estuary by allowing for site-specific carbon estimates. For example, a landowner could use this tool to estimate the blue carbon benefits of restoring diked agricultural lands to tidal marsh or forested tidal wetlands on their property. If any landowners choose to pursue these benefits, they can leverage public and private restoration funding, such as the Natural Resources Conservation Service’s voluntary Wetlands Reserve Easement program, which helps private and Tribal landowners protect, restore, and enhance wetlands.

The tool can support Oregon’s climate law goals

By identifying key blue carbon habitats and restoration opportunities, the tool can support measures enacted under the new law that leverage Oregon’s natural and working lands to advance state climate goals. Specifically, the tool can support ongoing tracking and evaluation of coastal wetlands by:

1. Providing alternative scenarios for land management that can increase carbon sequestration. The tool can compare different restoration outcomes. For example, a user can compare blue carbon values in a habitat without restoration, when a habitat is restored to an emergent wetland, and when it is restored to a scrub-shrub wetland.
2. Identifying blue carbon estimates for various land uses. The tool estimates greenhouse gas emissions and removals for diked agricultural lands, restored tidal wetlands, and conserved natural tidal wetlands.
3. Illustrating the carbon sequestration potential of Oregon’s natural and working lands. The tool illustrates potential blue carbon values with restoration at three time horizons: 15 years, 30 years, and 50 years.

Utility extends beyond Oregon

Although the tool is Oregon-specific, other states can invest in similar efforts to better understand where conservation and restoration opportunities may lie to protect and expand blue carbon habitats. As a first step, states can develop a baseline accounting of their blue carbon resources and then expand that with mapping and data features similar to those in the Oregon tool.

Blue carbon data tools can help localities and states leverage their coastal wetlands in support of climate goals, while also capitalizing on increased interest among public and private funders to invest in nature-based strategies that help mitigate climate change.

Alex Clayton Moya and Elizabeth Ruther are officers with The Pew Charitable Trusts’ U.S. conservation project.