Restored coastal ecosystems may not be the natural climate response, says recent study

A recent study suggests that restoring coastal vegetation, or so-called “blue carbon” ecosystems, may not be the oft-vaunted natural climate response.

Researchers refute the widespread belief that restoring ecosystems, including mangroves, salt marshes and seagrasses, can significantly reduce atmospheric carbon dioxide (CO2).

Blue carbon habitats for carbon removal

(Photo: Benjamin L. Jones/Unsplash)


Researchers from the University of East Anglia (UEA), the Center National de la Recherche Scientifique (CNRS) and the Prince Albert II of Monaco Foundation are challenging the widespread belief that restoring habitats such as mangroves , salt marshes and seagrasses can remove significant amounts of carbon dioxide (CO2) from the atmosphere in their analysis.

The results of their analysis, which were published today in the journal Frontiers in Climate, include seven factors that make carbon accounting for coastal ecosystems both dangerous and very difficult.

Significant variability in carbon burial rates, sensitivity to future climate change, and fluxes of methane and nitrous oxide are some of these.

The authors, who also reviewed data on restoration costs, caution that taking extra precautions can reduce these risks.

However, they emphasize that blue carbon ecosystems should always be preserved and, where possible, rehabilitated, as they are useful for biodiversity conservation, climate adaptation and coastal protection.

We have looked at the mechanisms of carbon removal, but there are simply too many unknowns, according to lead scientist Dr Phil Williamson, honorary reader at UEA’s School of Environmental Sciences.

Although restoring the blue carbon ecosystem may lead to the expected climate benefits, it seems more likely that they will be woefully disappointing.

The sediments that lie beneath mangrove forests, salt marshes and seagrass beds are rich in organic carbon that has been collected and stored for hundreds of years.

The potential of these coastal blue carbon ecosystems to contribute to a natural climate solution has been positively identified in many recent studies and reviews in two ways: through conservation, which reduces greenhouse gas emissions resulting from the loss and the degradation of these habitats, and through restoration. , which increases carbon dioxide uptake and long-term storage.

In assessing the viability of achieving measurable and safe carbon removal (negative emissions) through the restoration of coastal vegetation, this new assessment focuses on the latter.

If we rely heavily on these ecosystems to offset our carbon emissions expecting them to remove up to, say, 100 gigatonnes of carbon dioxide between 2025 and 2100, but instead find that they remove only 10 or even a single gigatonne of CO2, then Dr Williamson warned that climate tipping points could be passed with very serious repercussions.

However, assuming other methods are used for climate mitigation, it would be a bonus if these ecosystems were restored to maintain biodiversity and we found that they also removed many gigatonnes of CO2.

Therefore, restoration must be done in addition to near-total emission reductions, not instead of them.

Read more: Carbon dioxide and mangroves: equivalent to removing cars from the road

blue carbon

The term “blue carbon” simply refers to the carbon that the world’s ocean and coastal ecosystems have stored, according to NOAA.

You’ve probably heard that carbon dioxide, which includes atmospheric carbon, is emitted (or emitted) by human activity.

Additionally, you may have heard that these gases negatively affect the climate of the entire planet.

What you may not know is that the sequestration (or absorption) of carbon by our oceans and coasts offers a natural solution to mitigating the effect of greenhouse gases on our climate.

Along our coast, seagrass beds, mangroves and salt marshes “capture and hold” carbon, functioning as what is known as a carbon sink.

Although much smaller than the planet’s forests, these coastal systems can sequester this carbon at a much higher rate and for millions of years.

Most of the carbon absorbed by these ecosystems is stored underground, out of sight, but it is still there.

Preserving coastal habitat is crucial to the larger picture of blue carbon.

A significant amount of carbon is released into the atmosphere when these systems are disrupted, which can contribute to climate change.

Therefore, a smart strategy to slow climate change is to conserve and restore coastal ecosystems.

The restoration procedure improves the environment and the financial health of the community by doing so when there is less pollution to tax.

Related article: Experts question the reliability of blue carbon in restoring coastal vegetation

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