2. What is Blue Carbon?
• Blue carbon is the carbon stored in coastal and marine
ecosystems. It is mostly the carbon dioxide removed from the
atmosphere by the world's coastal ocean ecosystems,
mostly mangroves, salt marshes, seagrasses and
potentially macroalgae, through plant growth and the
accumulation and burial of organic matter in the soil.
• The coastal ecosystems of mangroves, tidal marshes, and
seagrass meadows provide numerous benefits and services that
are essential for climate change adaptation along coasts globally,
including protection from storms and sea level rise, prevention of
shoreline erosion, regulation of coastal water quality, provision of
habitat for commercially important fisheries and endangered
marine species, and food security for many coastal communities.
• Additionally, these ecosystems sequester and store significant
amounts of coastal blue carbon from the atmosphere and ocean
and hence are now recognized for their role in mitigating climate
change.
3. History
• The ocean, atmosphere, soil, and terrestrial forest
ecosystems have been the largest natural carbon (C) sinks.
• New research on the role of vegetated coastal ecosystems has
highlighted their potential as highly efficient C sinks, and led to
the scientific recognition of the term "Blue Carbon".
• "Blue Carbon" designates carbon that is fixed via coastal ocean
ecosystems, rather than traditional land ecosystems, like forests.
Although the ocean's vegetated habitats cover less than 0.5% of
the seabed, they are responsible for more than 50%, and
potentially up to 70%, of all carbon storage in ocean sediments.
• Mangroves, salt marshes and seagrasses make up the majority
of the ocean's vegetated habitats but only equal 0.05% of the
plant biomass on land. Despite their small footprint, they can
store a comparable amount of carbon per year and are highly
efficient carbon sinks.
• Seagrasses, mangroves and salt marshes can capture carbon
dioxide (CO2) from the atmosphere by sequestering the C in their
underlying sediments, in underground and below-ground
biomass, and in dead biomass.
4. The Blue Carbon Initiative
• The International Blue Carbon Initiative is a coordinated, global
program focused on mitigating climate change through the
conservation and restoration of coastal and marine ecosystems.
• Motto : "Mitigating climate change through coastal ecosystem
management."
• The Blue Carbon Initiative focuses on mangroves, salt marshes and
seagrasses, which are found on every continent except Antarctica.
These coastal ecosystems cover between 13.8 and 15.2 million
hectares (Mha), 2.2 and 40 Mha, and 17.7 and 60 Mha, respectively.
Combined, these ecosystems cover approximately 49 Mha.
• The Blue Carbon Initiative works to protect and restore coastal
ecosystems for their role in reducing impacts of global climate
change. To support this work, the Initiative is coordinating the
International Blue Carbon Scientific Working Group and
International Blue Carbon Policy Working Group, which provide
guidance for needed research, project implementation and policy
priorities.
• Projects are being developed at sites globally to protect and restore
coastal ecosystems for their "blue" carbon value. Research into
the sequestration, storage and loss of carbon from blue carbon
systems is ongoing.
5. Types of Blue Carbon ecosystems
Mangroves:
• Mangroves are a type of tropical forest, found at the edge of land
and sea and flooded regularly by tidal water. Mangroves are among
the most carbon-rich forests in the tropics. It is estimated that the -
average annual carbon sequestration rate for mangroves averages
between 6 to 8 Mg CO₂e/ha (tons of CO₂ equivalent per hectare).
These rates are about two to four times greater than global rates
observed in mature tropical forests.
• Mangroves provide at least US $1.6 billion each year in ecosystem
services, which include: supporting fisheries by providing important
spawning grounds for commercial fish species; filtering pollutants
and contaminants from coastal waters and contributing to healthy
coastal marine water quality; and protecting coastal development
and communities against storms, floods and erosion.
• In the last 50 years, between 30-50% of mangroves have been lost
globally and they continue to be lost at a rate of 2% each year.
• Major causes of destruction to mangrove ecosystems include
deforestation for construction of aquaculture ponds and other forms
of unsustainable coastal development. Experts estimate that
emissions from the degradation of mangroves can be as high as
10% of total emissions from deforestation globally, even though
mangroves account for only 0.7% of tropical forest area.
6. Tidal marshes:
• Tidal marshes are coastal wetlands with deep soils that are built
through the accumulation of mineral sediment and organic material
and then flooded with salty water brought in by the tides.
• Almost all of the carbon in tidal marsh ecosystems is found in the
soil, which can be several meters deep.
• Similarly to mangrove and seagrass habitats, marshes also serve as
important carbon sinks, Marshes sequester C in underground
biomass due to high rates of organic sedimentation and anaerobic-
dominated decomposition.
• Salt marshes cover approximately 22,000 to 400,000 km2 globally,
with an estimated carbon burial rate of 210 g C m−2 yr−1.It is
estimated that the average annual carbon sequestration rate for tidal
marshes averages between 6 to 8 Mg CO2 e/ha (Mg of
CO2 equivalent per hectare). These rates are about two to four times
greater than those observed in mature tropical forests.
• Tidal marshes filter pollutants from land runoff and hence help
maintain water quality in coastal areas. They provide critical habitat
for many stages of the life cycle of important marine species, which
is essential for healthy fisheries and coastal marine ecosystems.
• Tidal marshes also serve as a buffer to coastal communities,
absorbing some energy from storms and floods and helping to
prevent erosion. Tidal and freshwater marshes are being lost at a
rate of 1-2% per year.
• Major threats to tidal marsh ecosystems include draining for coastal
development, conversion to agriculture, and rising sea levels.
7. Seagrasses:
• Seagrasses are submerged flowering plants with deep roots that are
found in meadows along the shore of every continent except
Antarctica.
• Carbon accumulates in seagrasses over time which are anoxic and thus
continually preserve organic carbon from decadal-millennial time
scales and is stored almost entirely in the soils, which have been
measured up to four meters deep.
• Carbon sequestration rates in seagrass meadows vary depending on
the species, characteristics of the sediment, and depth of the habitats,
but on average the carbon burial rate is approximately 138 g C
m−2 yr−1.
• Although seagrasses account for less than 0.2% of the world’s
oceans, they sequester approximately 10% of the carbon buried in
ocean sediment annually (27.4Tg of carbon per year). Per hectare,
seagrasses can store up to twice as much carbon than
terrestrial forests. The global seagrass ecosystem organic carbon
pool could be as high as 19.9 billion metric tons.
• Seagrass meadows filter sediment and other nutrients from the water
and are constantly building and securing sediment, which buffers
coasts from erosion, storms and flooding. They are also important
habitats for fisheries and flagship marine species, such as sea turtles
and manatees.
• Seagrasses are among the world’s most threatened ecosystems, with
annual global loss of around 1.5% and accelerating in recent
decades*. Globally, about 29% of Earth’s seagrass ecosystems have
been lost*. Major threats to seagrasses include degradation of water
quality due to poor land use, such as deforestation and dredging.
8. Algae:
• Both macroalgae and microalgae are being investigated as
possible means of carbon sequestration. Because algae lack the
complex lignin associated with terrestrial plants, the carbon in
algae is released into the atmosphere more rapidly than carbon
captured on land.
• Algae have been proposed as a short-term storage pool of
carbon that can be used as a feedstock for the production of
various biogenic fuels.
• Another novel approach to carbon capture which utilizes algae is
the Bicarbonate-based Integrated Carbon Capture and Algae
Production Systems (BICCAPS) developed by a collaboration
between Washington State University in the United States and
Dalian Ocean University in China.
• Many cyanobacteria, microalgae, and macroalgae species can
utilize carbonate as a carbon source for photosynthesis. In the
BICCAPS, alkaliphilic microalgae utilize carbon captured from
flue gases in the form of bicarbonate.
• In South Korea, macroalgae have been utilized as part of a
climate change mitigation program. The country has established
the Coastal CO2 Removal Belt (CCRB) which is composed of
artificial and natural ecosystems. The goal is to capture carbon
using large areas of kelp forest.
9. Where are coastal blue carbon ecosytems found?
• Coastal blue carbon ecosystems are found along the coasts of every
continent except Antarctica.
• Mangroves grow in the intertidal zone of tropical and subtropical shores.
Countries with the highest areas of mangroves include Indonesia, Australia,
Mexico, Brazil, Nigeria, Malaysia, Myanmar, Papua New Guinea, Cuba,
India, Bangladesh, and Mozambique.
• Tidal marshes are intertidal ecosystems occurring on sheltered coastlines
ranging from the sub-arctic to the tropics, though most extensively in
temperate zones, mainly in Europe, North-America, Australia and in the
higher latitudes of South-America and Africa.
• Seagrass meadows are communities of underwater-flowering plants found
in coastal waters of all continents except Antarctica . More than 60 seagrass
species are known to exist, and as many as 10 to 13 of them may co-occur
in tropical sites.
• While several countries are embarking on efforts to better map and quantify
these systems, regional, and global maps of coastal blue carbon hot spots
currently do not exist.
Fig : Coastal blue carbon ecosystem in NDCs
10. Importance of the Blue Carbon Ecosystem
• When protected or restored, blue carbon
ecosystems sequester and store carbon.
• When degraded or destroyed, these ecosystems
emit the carbon they have stored for centuries
into the atmosphere and oceans and become
sources of greenhouse gases.
• Experts estimate that as much as 1.02 billion
tons of carbon dioxide are being released
annually from degraded coastal ecosystems,
which is equivalent to 19% of emissions from
tropical deforestation globally.
• Mangroves, tidal marshes and seagrasses are
critical along the world's coasts, supporting
coastal water quality, healthy fisheries, and
coastal protection against floods and storms. For
example, mangroves are estimated to be worth
at least US$1.6 billion each year in ecosystem
services that support coastal livelihoods and
human populations around the world.
11. CRITICAL STORAGE
OCEAN + COASTAL HABITATS
83% 2% 50%
GLOBAL CARBON COASTAL HABITAT SEDIMENT CARBON
83% of the global COVERAGE Coastal habitats
carbon cycle is Coastal habitats cover account for approx. half
circulated through less than 2% of the of the total carbon
the ocean. total ocean area. sequestered in ocean
sediments.
13. Coastal and marine ecosystems are important
for climate change mitigations
• The coastal ecosystems of mangroves, seagrass meadows and tidal
marshes mitigate climate change by sequestering carbon dioxide (CO2)
from the atmosphere and oceans at significantly higher rates, per unit area,
than terrestrial forests.
• The carbon deposits accumulated within these systems are stored
aboveground in the biomass of plants (tree trunks, stems and leaves),
below ground in the plant biomass (root systems and rhizomes), and in the
carbon-rich organic soils typical to these ecosystems.
• Carbon is dominantly stored belowground in the soils of coastal
ecosystems. Of the coastal blue carbon stored within mangroves, tidal
marshes, and seagrass meadows, 50–99% is located in the soils below
ground. These rich soil carbon stores can be up to six meters deep below
the surface, where it can remain for very long times (up to millennia).
• Recent studies estimate carbon storage in the top meter of soil to be
approximately 280 Mg C ha−1 for mangroves, 250 Mg C ha−1 for tidal
marshes, and 140 Mg C ha−1 for seagrass meadows, equivalent to
1,030 megagrams of carbon dioxide equivalence per hectare (Mg CO2eq
ha−1) for estuarine mangroves, 920 Mg CO2eq ha−1 for tidal marshes, and
520 Mg CO2eq ha−1 for seagrass meadows. Adding the carbon in the
plants, the mean carbon storage is 1,494, 951 and 607 Mg CO2eq ha−1 for
mangroves, tidal marshes and seagrass meadows, respectively.
14. Compared to other ecosystems, blue carbon ecosystems
release significant amount of CO2 per unit area upon
conversion or degradation
• When coastal ecosystems are degraded, lost or converted to
other land uses, the large stores of blue carbon in the soils
are exposed and released as CO2 into the atmosphere or
ocean.
• Current rates of loss of these ecosystems may result in 0.15–
1.02 billion tons of CO2released annually.
• Although the combined global area of mangroves, tidal
marshes, and seagrass meadows equates to only 2–6% of
the total area of tropical forest, degradation these systems
account for 3–19% of carbon emissions from global
deforestation.
• Recent analysis suggests that the annual loss of the three
blue carbon ecosystems is resulting in emissions (0.45 Pg
CO2 yr−1 – see Table 1) similar to the annual fossil fuel
CO2 emissions of the United Kingdom (the world’s 9th ranked
country by emissions).
Fig : Coastal ecological restoration
Fig: Marine ecosytem degradation (Alaska dump)
15. Activities causing the high rate of loss of
coastal blue carbon ecosystems
• The main causes of conversion and degradation of blue carbon ecosystems vary around the world
but are largely driven by human activities.
• Common drivers are aquaculture, agriculture, mangrove forest exploitation, terrestrial and marine
sources of pollution and industrial and urban coastal development. These impacts are expected to
continue and be exacerbated by climate change.
• Globally, numerous policies, coastal management strategies, and tools designed for conserving and
restoring coastal ecosystems have been developed and implemented.
• Policies and finance mechanisms being developed for climate change mitigation may offer an
additional route for effective coastal management.
• Blue carbon now offers the possibility to mobilize additional funds and revenue by combining best-
practices in coastal management with climate change mitigation goals and needs.
16. Investing in the conservation and restoration of
coastal blue carbon ecosystems as a means of
resucing atmospheric carbon
• The income that can be generated by conserving
coastal ecosystems for their blue carbon storage
and/or sequestration potential is comparable to (or
may exceed) the income of many of the common
causes of conversion or degradation (such as fish
ponds, and livestock).
• Such carbon financing would be derived from a carbon
market or other regulatory mechanism. However, there
are specific conditions in which conservation or
restoration of coastal blue carbon ecosystems is
excessively costly, or the potential income from certain
land uses (such as hotels and tourist attractions) is
sufficiently lucrative, that carbon alone is not sufficient
motivation for conservation.
Fig: Cost effectiveness of carbon mitigation policy
17. Scientific certainity of the carbon sequestration,
storage and emissions from coastal blue
carbon ecosystems
• Scientists have developed robust methods to reliably
measure and monitor the blue carbon stored in the
vegetative biomass and soils of mangroves, tidal
marshes, and seagrasses.
• Similarly, effective methods exist to estimate the loss of
carbon from these systems if they are degraded or
converted.
• Protocols for measuring blue carbon stored in
mangroves have been established for some time and
related methods for tidal marshes and seagrass
meadows are now becoming standardized.
18. Current climate change policies, investments and
tools to conserve blue carbon
• A number of existing mechanisms exist that encourage climate
change mitigation through conservation and restoration of natural
systems.
• Many of these mechanisms can be adapted and applied to coastal
blue carbon ecosystems. However, most of these opportunities
focus on carbon found in the above ground vegetative biomass
and do not currently account for the carbon in the soil.
• International policy bodies like the United Nations Framework
Convention on Climate Change (UNFCCC) and others are
beginning to include blue carbon in their discussions of natural
ecosystems.
• Relevant mechanisms such as Reducing Emissions through
Decreased Deforestation (REDD+) and National Appropriate
Mitigation Actions (NAMAs) are emerging as means for
developing countries to access international carbon mitigation
financing streams and to implement programs and policies on the
national level.
• At local scales, Clean Development Mechanisms (CDMs) are
being developed to help fund climate mitigation actions that may
include coastal ecosystem conservation. And voluntary carbon
markets seem likely as a source of financial support for coastal
ecosystem conservation and restoration activities.
19. Coastal bluecarbon can motivate and support
conservation and restoration of coastal
ecosystems
• The significant and growing number of coastal blue carbon site-level demonstration projects are
currently being implemented by various countries and organizations around the world is strong
evidence of the capacity of blue carbon to motivate conservation.
• Examples include Livelihood Funds projects in the Sundarbans – India, Casamance – Senegal and
Yagasu – Indonesia; the Research Center for Coastal and Marine Resources, Ministry of Marine
Affairs and Fisheries in Indonesia; the Abu Dhabi demonstration project; and the Mikoko Pamoja
Mangrove Reforestation Project in Kenya.
• Other projects that focus on the sustainable management or restoration of coastal marine
ecosystems include the Zambezi Mangrove Carbon Project in Tanzania and Mozambique the
Canary Current Large Marine ecosystem Mangrove Project in Gambia, Senegal, Guinea Bissaau
and Guinea.
• The integration of coastal blue carbon projects into existing carbon markets and trading schemes
will further motivate development of site-level projects that protect mangroves, tidal marshes, and
seagrasses.