Remove carbon using “Green Carbon” habitat “Uncertain and unreliable” – Increase by that?

news7g07/29/2022

3 3 minutes read

Remove carbon using "Green Carbon" habitat "Uncertain and unreliable" - Increase by that?

UNIVERSITY OF EAST ANGLIA

Restoring coastal vegetation – so-called ‘green carbon’ habitats – may not be the nature-based climate solution it claims to be, according to a new study.

In their analysis, researchers from the University of East Anglia (UEA), the French Center National de la Recherche Scientifique (CNRS) and the Prince Albert II Foundation’s OACIS initiative of Monaco, challenge this view. It is widely believed that restoring areas such as mangroves, marshes and seagrasses can remove large amounts of carbon dioxide (CO2) from the atmosphere.

Their findings reviewpublished today in the magazine Borders in climateidentified seven reasons why carbon accounting in coastal ecosystems is not only extremely challenging but risky.

These include high variability in carbon landfill rates, vulnerability to future climate change, and streams of methane and nitrous oxide. The authors, who also looked at information on restoration costs, warn that additional measurements can reduce these risks, but mean much higher costs.

However, they stress that green carbon habitats still need to be protected and restored where possible, as they are beneficial for climate adaptation, coastal protection, food supply and biodiversity conservation. biological form.

Lead author Dr Phil Williamson, honorary reader at the UEA’s School of Environmental Sciences, said: “We looked at the processes involved in carbon removal and there was so much uncertainty. The expected climate benefits from the restoration of green carbon ecosystems can be achieved, but they appear to be severely short-lived.

“If you want to remove more carbon, you need more habitat and the scope for recovery is limited. Many of these sites have been built for coastal settlement, tourism, and port development.

“However, we believe every effort should be made to prevent, and wherever reversible, the worldwide loss of coastal vegetation. That’s because green carbon habitats are more than just a carbon store – they also provide storm protection, support biodiversity and fisheries, and improve water quality.”

The sediments beneath mangrove forests, tidal mangroves and seagrass meadows are rich in organic carbon, which has been accumulated and stored over hundreds of years.

Many recent studies and assessments have favorably identified the potential of these coastal green carbon ecosystems to provide a natural climate solution in two ways: by conservation, by reducing emissions. greenhouse gases from the loss and degradation of those habitats, and by recovery, to the increase or decrease of carbon dioxide and its long-term storage.

This new assessment focuses on the latter, assessing the feasibility of achieving quantification and carbon removal (negative emissions) through coastal vegetation restoration.

More and more businesses and states are pledging to offset their emissions by restoring these ecosystems through carbon credits, assuming reliable knowledge of the amount of CO2 they will removed from the atmosphere in the future.

However, Dr Williamson and co-author, Professor Jean-Pierre Gattuso, of the CNRS and the Prince Albert II Foundation’s OACIS initiative of Monaco, say the policy issue is more complicated. That is, removing CO2 using coastal green carbon recovery is questionably cost-effective when considered only as a climate mitigation action, for carbon offsets or for inclusion in National Contributions. identification of countries, which sets out their efforts to reduce emissions and adapt to the impacts of climate change within the framework of the Paris Agreement.

“If we use these ecosystems to offset carbon in a major way, it is expected that they will remove up to 100 gigatonnes of carbon dioxide between 2025-2100, but find that they only remove 10 or so can be just one gigatonne of CO2, Dr. Williamson said.

“However, if such ecosystems are restored to protect biodiversity, and we find that they also remove some gigatonnes of CO2, that would be a bonus, assuming other means are provided. used for climate mitigation.

“Therefore, restoration must be complementary, not a substitute, for a near-total reduction in emissions. Where coastal green ecosystem restoration projects are undertaken primarily to remove carbon, they need to include comprehensive monitoring over the long term to verify that projected climate benefits ants are being achieved. ”

Professor Gattuso said: “Many important issues related to carbon flow measurement and storage remain unresolved, affecting certification and leading to the potential for overwriting.

“However, the restoration of coastal green carbon ecosystems is very beneficial for climate adaptation, coastal protection, food supply and biodiversity conservation. Thus, such action may be socially justifiable in many cases, given the many benefits such habitats provide at the local level.”

‘Carbon removal using coastal green carbon ecosystems is uncertain and unreliable, with questionable climate cost-effectiveness’Phillip Williamson and Jean-Pierre Gattuso, published in Borders in climate on July 28.

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