How to save sinking cities and bleaching corals?

bleaching coral
© Shallow corals begin to bleach in eastern Indonesia. (Photo: Ethan Daniels)

New research finds that a two-pronged approach is necessary to fight things like sea-level rise and ocean acidification.

There has been a lot of talk about whether individual acts in fighting for the environment can really make a difference; and similar things can be said about cities. Are local conservation endeavors effective, or should the focus be on working toward global efforts to reduce fossil fuel emissions?

Scientists are split on the matter, some arguing for a continuation of local environmental efforts, while others believe we need all hands on deck and should be shifting the focus on global efforts.

As it turns out, we need to be doing both things, according to researchers from Duke University and Fudan University, who wanted a better understanding of the interactions between climate change and local human impacts in coastal zones, which are the most densely populated regions in the world.

"The answer is, you need both," said Brian R. Silliman, from Duke's Nicholas School of the Environment. "Our analysis of local conservation efforts shows that in all but extreme situations, these interventions significantly buffer the impacts of climate change and can buy our sinking cities and bleaching corals time to adapt until the beneficial impacts of global emissions reductions kick in."

The paper provides examples of how local efforts have been crucial in staving off harm, and the authors provide proof that smaller victories are crucial. Or as the authors put it, "...an enhanced understanding of interactions between climate change and local human impacts is of profound importance to improving predictions of climate change impacts, devising climate-smart conservation actions, and helping enhance adaption of coastal societies to climate change in the Anthropocene."

In the Florida keys, for example, "local efforts to cull populations of coral-eating snails reduced thermal bleaching on corals by 40% compared to bleaching on non-treated corals during a three-month spike in water temperatures in 2014. It also promoted faster recoveries," notes Duke University in a statement.

They write about Chesapeake Bay's return of seagrass beds that were wiped out by warming waters and heavy pollution, thanks to local efforts to cut nutrient pollution flowing into the bay. Or Shanghai's tighter controls on groundwater use which have slowed down the sinking of the city as groundwater aquifers become depleted.

"A common thread in many of the most successful scenarios we reviewed is that the local actions increased climate resilience by removing or reducing human-related stresses that were compounding climate stresses and increasing a species' or site's vulnerability," said paper co-author, Qiang He, professor of coastal ecology at Fudan University in Shanghai.

venice steps© Steps in the sinking city of Venice, Italy, have become part of the intertidal zone. (Photo: Brian Silliman/Duke)

Another way to illustrate the importance of local action is to show what happens without it. In Jakarta, Indonesia, massive groundwater withdrawal is causing the city to sink by almost 10 inches a year. Duke notes, "By 2050, 95% of the city will be submerged as a result of the compounding effects of sea-level rise and human actions."

"Because Jakarta – unlike Shanghai – did not decrease its human impacts through local conservation or adaptation, the government's only recourse now is to move the entire city to a new, higher location on the island of Borneo," Silliman said.

"Unfortunately, other massive migrations of cities inland will become more and more common in coming decades, but we can reduce their number and how quickly they have to happen if we take dual action now on the local and global fronts," he continued. "For certain, this is no time to scale back on local conservation. We need to increase our investment at all scales."

So if you are frustrated by the feeling that our voices may not have much impact on a global level, have faith that working on behalf of local efforts is equally important. Become a local activist, speak to your legislators, spread the word. It may seem like treating the symptoms rather than curing the illness, but right now we need to be doing both.

The peer-reviewed paper, Climate Change, Human Impacts, and Coastal Ecosystems in the Anthropocene, was published in Current Biology

How to save sinking cities and bleaching corals?
New research finds that a two-pronged approach is necessary to fight things like sea-level rise and ocean acidification.

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