Blue Carbon

What is the impact of increased seaweed farming

Increased farming is potentially not increasing marine carbon sequestration

What are climate change goals

Keep warming below 2°C, reduce CO2 emissions, remove CO2 from atmosphere (100-1000Gt)

What is black carbon

Char produced by partially burning biomass, and soot by the burning of fossil fuels

What is brown carbon

Organic compounds

What is red carbon

Snow/ice microbes—produce red/purple pigments

What is blue carbon

Carbon stored by the ocean & sediment

What is teal carbon

Carbon stored in inland freshwater wetlands

What is green carbon

Carbon sequestered by land ecosystems, soil and & forests

What is the importance of blue carbon

These ecosystems sequester carbon at rates higher than terrestrial forests

What is seaweed’s role in blue carbon

Seaweeds absorb CO2 through photosynthesis, they store CO2 through living biomass, particulate organic carbon, dissolved organic carbon, sedimentary deposits

What is the challenge with seaweed storing carbon

Hard to quantify long-term storage and ensure that carbon remains sequestered, short lived with rapid turnover time, do nor store carbon as living biomass on timescales relevant to sequestration, fate of kelp biomass depends on various environmental factors (temp, aerobic, anaerobic)

What is the timescale for CO2 to equilibrate with seawater in coastal oceans

weeks to months

What is the timescale for CO2 to equilibrate with seawater in open oceans

Months to a year

What is the timescale for CO2 to equilibrate with seawater in the Arctic

More than a year

Describe process of Carbon Dioxide Removal (CDR)

CO2 gas exchange occurs at surface water → CO2 dissociates, seaweed takes up CO2 and bicarbonate → fast processes produce a CO2 deficient “bubble” of water → the low CO2 water moves on to mix with the rest of the water and change the equilibrium (in offshore regions the low CO2 water parcel can be trapped under another water parcel causing incomplete equilibrium, can take months to equilibrate)

Benefits of seaweed farming

Carbon sequestration, water quality improvement, economic opportunities

Challenges with seaweed farming

Regulatory frameworks, environmental impacts, market development

Risks associated with aquaculture

Possible release of volatile halocarbons, release of DOC affecting phytoplankton and bacteria communities, possible methane release from seaweed deposition, deposition of seaweed causing hypoxia, interaction between farmed seaweed and benthic communities, risk of entanglement of marine life, nutrient competition with phytoplankton communities

What do we lack when it comes to seaweed farming especially in NZ

Have limited data on seaweed’s contribution to the national carbon cycle, research gaps in quantification of carbon storage in seaweed beds and impact of climate change on seaweed ecosystems

What are national strategies related to blue carbon

The inclusion of blue carbon in climate action plans

What are regulatory frameworks around blue carbon

Development of standards for carbon credits

What are the challenges associated with policy and governance in blue carbon

Policy alignment, monitoring and verification, equitable benefit-sharing