Can Marine Protected Areas Attenuate Climate Change?

Even if the world does its best to reduce carbon emissions and combat climate change, rising carbon dioxide concentrations will continue to harm the oceans for decades to come. A new paper argues that marine protected areas (MPAs) are a cost-effective way to mitigate the worst that climate change has brought to the oceans.

MPAs, where fishing and human exploitation activities are prohibited or severely curtailed, are generally said to have the potential to restore fish stocks and marine biodiversity. But a new paper published this week in the journal PNAS looks at the positive effects of marine protected areas from a different perspective.

The paper provides evidence that MPA can reduce the acidity of ocean waters, mitigating impacts such as rising sea levels and intensifying storms. MPAs can also serve as safe havens for species no longer suitable for their original habitat, and as fish farms for reviving species from waters depleted by low oxygen and nutrient deficiencies. can. The paper also highlights how MPAs help offset global carbon emissions through carbon storage and sequestration.

“Marine ecosystems have sequestered carbon for thousands of years to have oil and coal today,” said one of the study’s authors and director of research at the University of British Columbia’s Sea Around Earth Project.

“This paper reiterates the obvious that (large) ecosystems benefit from the establishment of marine reserves where nature can re-examine itself,” he said. Stated.

The acidity of surface seawater has increased by an average of 26% since the industrial revolution due to the increase in atmospheric carbon dioxide concentration, and is a problem for many marine organisms. The paper thinks fish may be able to alleviate this problem. Fish are known to absorb calcium from seawater, binding it to carbon and secreting weakly alkaline carbonate molecules that can neutralize ocean acidification. Fish that live in meso-deep sea layers (water depths between 200 and 1000 meters) swim daily between the calcium-rich deep sea and the surface layer of the ocean that releases calcium carbonate. The paper argues that adding more MPAs in the open ocean to protect such fish could mitigate ocean acidification.

According to the paper, MPAs can also moderate violent and powerful storms resulting from rising sea levels and warm water temperatures. With coastal marshes, salt marshes and mangrove forests, MPAs protect the land behind them by dampening storms and mitigating floods.

“Mangroves are cheaper than building a barrier,” Pauly said.

Rising ocean temperatures are altering some marine ecosystems, displacing a large number of species to make them inhospitable marine environments. The paper concludes that regionally networked MPAs can act as stepping stones to stop this migration, reducing the risk of local extinction of species or isolation of populations.

MPAs may also prevent an increase in the incidence of nutrient-poor ‘sea deserts’ and a depletion of oxygen in the upper oceans, both phenomena linked to climate change, according to the paper. It says. Healthy MPAs can not only evacuate species from these dead zones, but may also help regenerate species in nearby waters. The paper describes how high abalone spawning within the MPA waters of the Baja California peninsula, Mexico, hastened the recovery of nearby waters suffering from increasingly frequent hypoxic episodes.

Marine plants such as seagrasses globally absorb carbon dioxide and transform it into vegetation, and swamps then sequester this recovered carbon dioxide. Collapse of seagrass habitats and swamps not only loses this form of carbon sequestration, but also releases already stored organic carbon into the carbon cycle. The paper points out that these effects can be thwarted by protecting the MPA.

According to Pauly and co-authors, all of this is reason enough to increase the size and number of MPAs on a global scale. Currently, only 5.7% of marine areas are classified as protected areas, much of which is in need of better management, said Christiana Pasca Palmer, Executive Director of the United Nations Convention on Biological Diversity (CBD), in a press release. Stated. Their current goal is to convert 10% of the sea area into MPAs for coastal states. However, the authors of the paper argue that the target should be closer to 30%.

“This paper makes a powerful argument at a time when we are seeking effective climate action,” Sarah Lester, an assistant professor of geography at Florida State University, who was not involved with the paper.

Lester, who is in charge of the MPA for the Caribbean, said he sees a big difference in marine protected areas where fishing is prohibited, saying, “Human livelihoods are highly dependent on healthy and functioning natural ecosystems. , we need to sustain marine ecosystems.”

But not everyone agrees that MPA is the best way. The paper acknowledges that some scientists are still actively debating the effectiveness of marine protected areas.

Ray Hilborn, a professor at the University of Washington/Department of Oceanography and Fisheries and a self-identified critic of the MPA, said that the fishing industry should minimize the environmental damage caused by fishing gear while being cautious about farming and increasing populations. I told that I could go ahead with it. He believes that unlike MPAs, which can only protect specific areas of the ocean, this method will protect all endangered marine habitats and species while still providing a stable food source for people.

It’s important to “think beyond the marine ecosystem and remember that the fisheries industry is linked to the world’s food supply,” Hilborn said. Reserving 30% of the ocean as no-fishing MPAs would mean more land-based food production would be needed, and conversion of excess forest to agriculture and livestock would produce significantly higher carbon footprints than fishing. He argues that quantity occurs.

Hilborn acknowledges that in countries like Southeast Asia, where fishing bans are less heavily regulated, it is easier to monitor a designated MPA than crack down on all territorial waters, but the United States, Canada, Australia, etc. I think that the MPA does not make sense in a country where the management of

Mr Pauly refutes claims that the MPA will limit the food supply. “Although the MPA is limiting the catch, we are getting more overall,” he said, adding that “some people think they have to sacrifice the catch for biodiversity.” A lot, but you really need biodiversity to produce fish,” he added.

That said, the paper acknowledges that catch limits and other regulations provide some benefits to MPAs, and that the success of MPAs depends “largely” on how well they are implemented and managed. It also recognizes that MPAs are not a substitute for reducing greenhouse gas emissions. But the paper emphasizes how important the protection of marine ecosystems plays and encourages further research into lesser-known mechanisms called ‘nature-based solutions’. ing.

“We’ve become accustomed to constantly modifying/transforming the world to what we think is beneficial,” said Pauly, “but the reality is that our human intervention is destroying ecosystems. .”

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