Our oceans and coasts cover 72% of the earth’s surface, and they have absorbed around 40% of the carbon emitted by humans since 1950. Their carbon absorption abilities and ecosystem services they provide make preserving them a crucial part of fighting climate change. So, we had to ask: How effective and efficient are blue carbon offsets?

Blue carbon offsets are effective at reducing CO₂ emissions by strengthening marine carbon sinks, yet often lack permanence and large-scale funding. They are efficient and cost-effective at reducing emissions, yet still miss standardized methodologies for assessing blue carbon storage.

Keep reading to find out how efficient and effective blue carbon offsets are, how you can offset your carbon footprint with them, what their pros and cons are, how they can mitigate climate change, and what better alternatives to blue carbon offsets are. 

The Big Picture of the Effectiveness and Efficiency of Blue Carbon Offsets

Carbon offsets are reductions in carbon emissions that are used to compensate for carbon emissions occurring elsewhere. They are measured in tons of carbon dioxide (CO₂) equivalents and are bought and sold through international brokers, online retailers, and trading platforms on what is known as the global carbon offset market. 

“Carbon Offset: a way for a company or person to reduce the level of carbon dioxide for which they are responsible by paying money to a company that works to reduce the total amount produced in the world, for example by reforestation”

Oxford Dictionary

Blue carbon offsets are a specific type of carbon offset that focuses on the preservation of coastal and marine ecosystems. Blue carbon is the carbon that is stored in coastal and marine ecosystems (e.g., mangroves, seagrasses, and salt marshes). 

“Blue Carbon: the term for carbon captured by the world’s ocean and coastal ecosystems.”

National Oceanic and Atmospheric Administration

There are over 120 million acres of blue carbon ecosystems worldwide that provide habitat for species, support food security, sustain coastal communities, and protect our coastlines. Mangroves are found in the intertidal zone of tropical and subtropical shores, seagrasses are found in coastal waters, and salt marshes are found mostly in temperate zones. 

Blue carbon is one example of biological carbon sequestration, or the storage of carbon in vegetation (forests), soils, and oceans, which are commonly referred to as our carbon sinks. Blue carbon offsets focus on preserving mangroves, seagrasses, and salt marshes, which constitute one of our largest carbon sinks yet are being degraded at 4x the rate of tropical forests. 

Here’s How Effective and Efficient Blue Carbon Offsets Are

In terms of effectiveness, blue carbon offsets reinforce our marine carbon sink and can continue to avoid CO₂ emissions after their project life span; however, they also often lack permanence and large-scale funding, and they do not reduce your own carbon emissions.

In terms of efficiency, blue carbon offsets are efficient at carbon sequestration and storage and are relatively cost-effective; however, they also lack a standardized methodology.

How Effective Are Blue Carbon Offset Programs at Reducing CO₂ Emissions

Effectiveness involves completing a task with a desired outcome, typically a successful one. 

“Effective: producing the result that is wanted or intended; producing a successful result”

Oxford Dictionary

Blue carbon offsets are effective at mitigating climate change because they reinforce our marine carbon sink; however, they also often lack permanence and large-scale funding, and they do not reduce your own carbon emissions.

Blue Carbon Offsets Increase Our Marine Carbon Sink’s Carbon Capacity

Blue carbon is one example of biological carbon sequestration, or the storage of carbon in vegetation (forests), soils, and oceans, which are commonly referred to as our carbon sinks. 

“Carbon Sink: an area of forest that is large enough to absorb large amounts of carbon dioxide from the earth’s atmosphere and therefore to reduce the effect of global warming”

Cambridge Dictionary

Our oceans are important in mitigating climate change because they absorb roughly 25% of the carbon we emit every year. The less carbon emitted into our atmosphere, the slower global temperatures will rise. This is important because when global temperatures increase, ice sheets, and glaciers melt and seawater expands, increasing the total volume of our oceans and resulting in sea level rise. 

Since 1993, our oceans have risen an average of 0.12-0.14 inches, twice as fast as the long-term trend. But if undisturbed, blue carbon ecosystems can absorb enough carbon to keep pace with moderate sea level rise. This in turn reduces the risks of coastal flooding, erosion, and mass displacement of people.

In the top meter of soil alone, mangroves can store an average of 1,494, seagrass meadows 951, and tidal marshes 607 tons of CO₂ per hectare, respectively. But the real value lies below the surface. Roughly 50–99% of the carbon stored in blue ecosystems is located in the soil underground. Carbon can remain stored at depths of up to 6 meters for up to 1,000 years.

In short, blue carbon offsets reinforce marine and coastal ecosystems, which are one of our biggest carbon sinks capable of absorbing billions of metric tons of CO₂ every year. 

Blue Carbon Offsets Can Continue to Avoid CO₂ Emissions After Their Project Life Span

Carbon emission reductions are delayed when you plant new mangrove forests because you have to wait for the trees to reach maturity before they can begin to reduce carbon emissions. However, these trees can continue absorbing carbon long after they mature, so long as they are not deforested. This means that blue carbon projects can continue to reduce carbon emissions long after mangroves have been planted.

The ability of blue carbon offsets to continue to reduce carbon after the project has been completed is dependent on the continued protection of the ecosystem. Blue carbon offsets do not necessarily protect trees after they have been planted; REDD+ carbon offsets are more concerned with protecting already existing forests. Meaning that any future carbon reductions could be negated if the trees are deforested before they can die naturally.

In short, blue carbon offsets continue to reduce carbon long after the project has been completed, so long as they are not deforested prematurely.

Blue Carbon Offsets Often Lack Permanence

In order to be effective, blue carbon offset projects must be permanent, in the sense that there must be a full guarantee against reversals of carbon emission for the foreseeable future. 

Blue carbon ecosystems have a leg up on terrestrial ecosystems in terms of permanence for a variety of reasons:

• Mangroves are more durable and lock away carbon more permanently than terrestrial forests (for example, blue carbon sinks are less susceptible to wildfires)
• There is less of a concern for leakage because coastal trees are not typically used for lumber

However, nature-based solutions, such as blue carbon, generally lack permanence. 

• Blue carbon ecosystems are currently being degraded at 4 times the rate of tropical forests.
• We are currently losing mangroves, seagrasses, and tidal marshes at a rate of 2%, 1.5%, and 1-2% per year, respectively.

Climate change is one of the leading factors that can negate blue carbon permanence. Coastal ecosystems are especially sensitive to sea level rise, storm intensity, and rising ocean temperatures, all of which have been occurring at an accelerated rate. Ocean acidification, a result of warming ocean temperatures, particularly threatens these ecosystems and the biodiversity they harbor.

In short, nature-based solutions, such as blue carbon efforts, often lack permanence because they are reversible.

Blue Carbon Offsets Lack the Large-Scale Funding They Deserve

Carbon credit certification for blue carbon projects can be costly because these projects are typically located in underdeveloped countries, in remote locations, and in locations difficult to traverse through. Historically, this has led to blue carbon offsets lacking sufficient financial support. 

Although they are capable of providing ⅓ of the total emissions reductions needed to keep global warming below 2 degrees Celsius, blue carbon ecosystems only receive 3% of total climate investments globally.

As more blue carbon methodologies are established, experts expect monetization of coastal wetland conservation and restoration activities to increase. And this is important to mitigating climate change because they are effective at absorbing carbon from the atmosphere and permanently storing it for long periods of time.

In short, blue carbon offsets lack sufficient financial support to implement them on a large scale.

Blue Carbon Offsets Do Not Reduce Your Own Carbon Emissions

In general, one of the main limitations of carbon offsetting is that purchasing a carbon offset does not directly reduce your carbon footprint. It only makes others reduce their carbon footprint to compensate for your carbon footprint. 

If emissions are only offset and not reduced from the source, this could lead to greenwashing, when the consumer is deceived into thinking they are offsetting their emissions but in reality, they are not. Companies accused of greenwashing either invest in non-verified credits, do not prioritize in-house emissions reductions, or double-count carbon credits. Or sometimes, all of the above.

In short, because blue carbon offsets do not reduce your own carbon emissions, they could lead to greenwashing.

How Efficient Are Blue Carbon Offset Programs at Mitigating Climate Change

Efficiency involves performing a task while using the least amount of resources and producing the least amount of waste as possible.

“Efficient: working in a way that does not waste a resource (= something valuable such as fuel, water, or money)”

Cambridge Dictionary

Blue carbon offsets are efficient at reducing CO₂ emissions because they are efficient at carbon sequestration and storage and are relatively cost-effective; however, they also lack a standardized methodology.

Blue Carbon Offsets Are Efficient at Carbon Sequestration and Storage 

Blue carbon ecosystems are efficient at trapping and storing carbon long-term because they can sequester carbon at higher rates per unit area than terrestrial ecosystems.

• Mangroves and salt marshes can absorb 3-5 times more carbon per acre than tropical rainforests forests do and at 10 times the rate. 
• Every square meter of seagrass is capable of removing 0.5 pounds of CO₂ per year, which is 3 times the rate of tropical rainforests, 7 times the rate of temperate forests, and more than 10 times the rate of grasslands. 

In addition, these ecosystems permanently store carbon at depths of up to 6 meters for up to 1,000 years. Collectively, seagrass meadows store 11% of the ocean’s buried carbon despite only accounting for only 0.1% of the world’s seafloor. 

In short, blue carbon ecosystems store carbon for long periods at higher rates than those of terrestrial ecosystems. 

Blue Carbon Offsets Are Relatively Cost-Effective

Sustainable Development Goal 14 (SDG 14), to conserve and sustainably use the oceans, seas and marine resources for sustainable development, is an expensive undertaking. Experts estimate that it will take $175 billion per year to meet SDG 14, 1/5 of which ($35 billion) is just for protecting and restoring wetland ecosystems, coastal habitats, and coral reefs. 

Blue carbon offsets could help finance this process, because they are typically more cost-effective than other categories of carbon offsets. For example, blue carbon offsets from leading providers (e.g., The Ocean Foundation, One Tree Planted, Reforest’Action, and South Pole) cost less than $30 per ton of CO₂ offset. Compare this to direct carbon capture offsets which can cost anywhere from $100-$1,200 per ton of CO₂ offset. 

In short, blue carbon offsets are relatively cost-effective when compared to other methods of carbon emission reduction.

Blue Carbon Offsets Lack a Standardized Methodology

The storage of carbon in terrestrial ecosystems is well documented and managed via the Reducing Emissions from Deforestation and Forest Degradation (REDD+) mechanism, which places an economic value on the actions a country takes to reduce deforestation and preserve forests. However, there is no overarching mechanism to regulate the carbon stored in coastal, marine, or wetland soils and biomass.

Leading standards all have different methodologies for assessing blue carbon. 

• Verra released the first blue carbon methodology modeled after the REDD+ mechanism in 2020. 
• The Gold Standard is developing their own methodology not based on REDD+.
• The American Carbon Registry has two methodologies, Restoration of Pocosin Wetlands and Restoration of California Deltaic Coastal Wetlands. 
• Salesforce and the World Economic Forum launched the High-Quality Blue Carbon Principles and Guidance carbon credit methodology in 2022.

A lack of standardization has also led to a lack of certified projects available on the voluntary carbon offset market (VCM). As of 2020, there were only 5 projects registered under approved methodologies, and all at a relatively small scale. The average project size was 300,000 tons of CO₂ over the project lifetime, compared with 2.4 million tons of CO₂ for other nature-based solutions.

In short, blue carbon offsets lack a standardized methodology, which leads to a lack of certified projects on the VCM.

How Could you Offset Your Own Carbon Footprint With Blue Carbon Offsets

The market for carbon offsets was small in the year 2000, but by 2010 it had already grown to represent nearly $10 billion worldwide. The voluntary carbon offset market (VCM) is where everyday consumers can purchase carbon offsets to offset their carbon emissions. 

The Ecosystem Marketplace predicts the VCM can grow to $50B by the year 2050. And because blue carbon offsets protect one of our largest carbon sinks, they are predicted to make up an increasingly larger share of this market.

What Are The 6 Pros and 4 Cons of Blue Carbon Offsets

Blue carbon offsets reinforce our marine carbon sinks, can continue to avoid CO₂ emissions after project durations, preserve biodiversity, help maintain water quality, are relatively cost-effective, and allow us to reduce carbon emissions in ways we wouldn’t be able to accomplish individually.

Blue carbon offsets often lack permanence, a standardized methodology, large-scale funding, and they do not reduce your own carbon emissions.

What Are the 6 Pros of Blue Carbon Offsets

Blue carbon offsets have various pros that make them effective at absorbing carbon from our atmosphere.

What Are the 4 Cons of Blue Carbon Offsets

Understanding the drawbacks of blue carbon offsets is important when implementing this strategy on a large scale in order to mitigate climate change.

How Can Blue Carbon Offsets Help Mitigate Climate Change

Climate change is a severe and long-term consequence of fossil fuel combustion. Blue carbon offsets can help mitigate climate change because they protect our coastal marine ecosystems. The healthier they are, the more CO₂ they can absorb from our atmosphere. Atmospheric carbon can, if left untreated, remain there for tens of thousands of years and exacerbate the negative effects of climate change.

How is Climate Change Defined

Climate change is arguably the most severe, long-term global impact of fossil fuel combustion. Every year, approximately 33 billion tons (bt) of CO₂ are emitted from burning fossil fuels. The carbon found in fossil fuels reacts with oxygen in the air to produce CO₂. 

“Climate change: changes in the earth’s weather, including changes in temperature, wind patterns and rainfall, especially the increase in the temperature of the earth’s atmosphere that is caused by the increase of particular gasses, especially carbon dioxide.”

Oxford Dictionary

Atmospheric CO₂ fuels climate change, which results in global warming. When CO₂ and other air pollutants absorb sunlight and solar radiation in the atmosphere, it traps the heat and acts as an insulator for the planet. Since the Industrial Revolution, Earth’s temperature has risen a little more than 1 degree Celsius (C), or 2 degrees Fahrenheit (F). Between 1880-1980 the global temperature rose by 0.07C every 10 years. This rate has more than doubled since 1981, with a current global annual temperature rise of 0.18C, or 0.32F, for every 10 years. 

As outlined in the 2015 Paris Climate Agreement, we must cut current GHG emissions by 50% by 2030 and reach net zero by 2050. 

How Do Carbon Offsets Generally Help Mitigate Climate Change

Levels of carbon in our atmosphere that cause climate change have increased as a result of human emissions since the beginning of the Industrial Revolution in 1750. The global average concentration of carbon dioxide in the atmosphere today registers at over 400 parts per million. Carbon offsets can help prevent these levels from increasing even more.

When you hear the words “carbon offset”, think about the term “compensation”. Essentially, carbon offsets are reductions in GHG emissions that are used to compensate for emissions occurring elsewhere. 

Carbon offsets that meet key criteria and verified project standards, are additional and permanent, and are part of projects that are carried out until the end of their lifespan have the best chance of reducing carbon emissions and therefore reducing climate change. 

When we offset CO₂ we also slow the rate of global temperature rise, which in turn minimizes the effects of climate change. 

How Do Blue Carbon Offsets Specifically Help Mitigate Climate Change

Blue carbon offsets specifically help mitigate climate change because they protect coastal and marine ecosystems, which are capable of absorbing more CO₂ per acre than rainforests and at a rate 10x greater. The more we reinforce these ecosystems, the more we enable them to absorb CO₂ from the atmosphere and store it in biomass and soils for long periods of time.

What Are Better Alternatives to Blue Carbon Offsets

If used correctly, blue carbon offsets can provide environmental, economic, and social benefits beyond reducing carbon emissions. They have the potential to instigate meaningful environmental change and begin to reverse some of the effects of climate change. 

However, we can’t let this method be a guilt-free way to reduce carbon emissions. Alone, blue carbon offsets will not be enough to outpace the negative effects of global warming. They must instead be used in conjunction with direct carbon reduction measures.

These reduction measures don’t have to involve drastic changes either. Actions that may seem small can have a big impact because those small changes add up! You can reduce your carbon footprint in three main areas of your life: household, travel, and lifestyle. 

Reduce your household carbon footprint:

• Wash with cold water: Washing clothes in cold water could reduce carbon emissions by up to 11 million tons. Approximately 90% of the energy is used to heat the water, so switching to cold saves also saves energy.

• Replace incandescent bulbs with fluorescent bulbs: Fluorescent bulbs use 75% less energy than incandescent ones, saving energy and thus reducing electricity demand and GHG emissions.

Reduce your travel carbon footprint:

• Fly less: Aviation accounts for around 1.9% of global carbon emissions and 2.5% of CO₂. Air crafts run on jet gasoline, which is converted to CO₂ when burned.

• Walk or bike when possible: The most efficient ways of traveling are walking, bicycling, or taking the train. Using a bike instead of a car can reduce carbon emissions by 75%. These forms of transportation also provide lower levels of air pollution.

Reduce your lifestyle carbon footprint:

• Switch to renewable energy sources: The six most common types of renewable energy are solar, wind, hydro, tidal, geothermal, and biomass energy. They are a substitute for fossil fuels that can reduce the effects of global warming by limiting global carbon emissions and other pollutants.

• Recycle: Recycling uses less energy and deposits less waste in landfills. Less manufacturing and transportation energy costs means fewer carbon emissions generated. Less waste in landfills means less CH₄ is generated.

• Switch from single-use to sustainable products: Reusing products avoids resource extraction, reduces energy use, reduces waste generation, and can prevent littering.

• Eat less meat and dairy: Meat and dairy account for 14.5% of global GHG emissions, with beef and lamb being the most carbon-intensive. Globally, we consume much more meat than is considered sustainable, and switching to a vegan or vegetarian diet could reduce emissions. 

• Take shorter showers: Approximately 1.2 trillion gallons of water are used each year in the United States just for showering purposes, and showering takes up about 17% of residential water usage. The amount of water consumed and the energy cost of that consumption are directly related. The less water we use the less energy we use. And the less energy we use, the less of a negative impact we have on the environment.

Because blue carbon offsets are an indirect way and not a direct way of reducing carbon emissions, they alone will not be enough to reduce global carbon emissions significantly. Direct measures of emission reductions, such as reducing individual energy use and consumption, are better alternatives to blue carbon offsets. 

Final Thoughts

Blue carbon offsets are effective because they reinforce our marine carbon sink and can continue to avoid CO₂ emissions after their project life span; however, they also often lack permanence and large-scale funding, and they do not reduce your own carbon emissions, which can lead to greenwashing. Blue carbon offsets are efficient because they are efficient at carbon sequestration and storage and are relatively cost-effective; however, they also lack a standardized methodology.

Carbon offsets can instigate meaningful change, but they should not be seen as the only solution to climate change. They are effective at reducing CO₂ in the short term, but in the long term, they fail to reduce CO₂ enough. 

When used in conjunction with direct CO₂ reduction measures, carbon offsetting can be much more effective. We should reduce our own carbon footprint as much as possible first, and only then choose the most effective carbon offsets.

Stay impactful,

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