Report on Evaluating Blue Carbon as an Effective Climate Mitigation Strategy for Canada

A Blue Carbon Working Group, composed of DFO and academic experts, was convened to evaluate whether the protection, restoration and expansion of blue carbon can meaningfully contribute to Canada's carbon reduction goals. In June 2024, the group participated in a workshop to jointly co-develop a report that provides a comprehensive overview of existing knowledge, key limitations and critical knowledge gaps by habitat type and geographic region. This report will serve as a basis for future research and policy development.

A summary of the report is available below. A primary publication is currently being developed by the workshop participants, building on the discussions and outcomes of the June 2024 workshop.

Executive Summary

Vegetated coastal ecosystems (in Canada: salt marshes, seagrass meadows, macroalgae beds) and unvegetated coastal sediments take up carbon dioxide (CO₂) and store substantial organic carbon on climate-relevant timescales (> 100 years), generating widespread interest in Blue Carbon as a natural climate solution.

Major information gaps in Canada (and globally) include: detailed mapping and risk assessment for stored carbon; detailed mapping of areas of potential habitat expansion; measurements of carbon burial rates in different environments; timescales of preservation of particulate and dissolved carbon exported from macroalgae/seagrass beds; reduction in net CO₂ drawdown resulting from inorganic carbon burial; natural emission rates of non-CO₂ greenhouse gasses (methane, nitrous oxide) from Blue Carbon ecosystems.

Work underway in Canada will help to address the gaps identified above; however, these gaps require significantly more research.

Canada could potentially expand its Blue Carbon ecosystems by restoring degraded areas or by expanding into new areas. These efforts could draw down additional CO₂.

Disturbance of ecosystems or their soils and sediments could potentially release stored carbon, increasing Canada's CO₂ emissions. Coastal development and climate change particularly threaten Blue Carbon ecosystems, in tandem with potential loss of carbon stored in unvegetated sediment through dredging.

Although we lack detailed data for either potential expansion or potential loss of Blue Carbon habitats, the relative merits of these two Blue Carbon pathways need evaluation. Despite expectations that loss rates will occur at a much higher rate than any expansion rates, their balance may differ by ecosystem type based on 1) the area for potential expansion compared to existing areas of vegetated ecosystems; and 2) timeframes for accumulated carbon - where loss relates to instantaneous or gradual loss of carbon built up over hundreds or thousands of years, whereas new carbon gains would only accumulate slowly one year at a time.

A funding mechanism accessible to collaborating government and non-government scientists/organizations, communities-based practitioners, and First Nations would enhance data integration, reduce redundancies, and support a coordinated approach.

Even while lacking information to quantify the climate mitigation benefits of Blue Carbon, protecting these ecosystems would provide multiple complementary benefits: protection of critical habitat, shoreline protection, cultural values, food security, tourism, alongside protection of existing carbon stocks. Assessing a Blue Carbon implementation pathway for Canada will require full ecological and economic valuation of Blue Carbon ecosystems.