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Earth Day Opinion: Helping Coral Ecosystems Survive a Changing Climate

By Dr. Tim McClanahan As we mark Earth Day this year with a recognition of “the face of climate change,” it is clear that the greatest threat to coral reef ecosystems is rising sea temperatures. With corals across the globe bleaching due to advancing ocean temperatures, many of the world’s coral reef experts believe these...

By Dr. Tim McClanahan

As we mark Earth Day this year with a recognition of “the face of climate change,” it is clear that the greatest threat to coral reef ecosystems is rising sea temperatures.

With corals across the globe bleaching due to advancing ocean temperatures, many of the world’s coral reef experts believe these centers of marine biodiversity may become the first casualty of climate change. But while the news on corals has been largely grim, it is not beyond hope.

Starfish - Tim McClanahan
Starfish – Tim McClanahan

First, the bad news. In the past 20 years, Caribbean corals have been smothered by algae, while bleaching events in the Indian Ocean and Pacific Oceans have damaged huge swaths of previously healthy reef systems. A recent model published in Nature Climate Change predicts that 70 percent of corals are expected to undergo long-term degradation by 2030.

Yet these models represent an incomplete understanding of temperature-coral survival dynamics.

The notion that all is lost is misguided, and risks our resignation in confronting this crisis. Such a doomsday perspective ignores the resilience of coral reefs, our current incomplete understanding of their stress dynamics, and the ability of many of these systems to adapt to changing conditions.

Yellow Crinoid - Tim McClanahan
Yellow Crinoid – Tim McClanahan

Knowing exactly which reefs will survive the extinction bottleneck to come is a critical step in knowing where to commit vital management resources.

Over the past few years, the Wildlife Conservation Society (WCS) and other like organizations around the world have published studies that offer solutions for identifying the corals most likely to survive our changing climate. One of these solutions is a “stress test.”

By combining layers of historical data, satellite imagery, and field observations gathered with scuba diving, marine scientists have produced a map that highlights low-stress places most likely to benefit from immediate conservation effort.

Tim McClanahan
Tim McClanahan

As a result of the analysis we know, for example, that the oceans around Southern Kenya, Tanzania and Mozambique across to northeastern Madagascar contain corals with high diversity and low to moderate environmental stress that merit protection in a region recently decimated by coral bleaching. These are also areas where millions of people depend on coral reefs for food, fisheries, associated livelihoods, and coastal protection.

On a wider scale, coral experts have created a map of the world’s corals with data on the exposure of these centers of biodiversity to stress factors, including high temperatures, ultraviolet radiation, temperature variability, and overfishing by humans.

By identifying corals where biodiversity is high and stress factors are low, we can protect what is most likely to survive in a scientifically meaningful way. For all who wish to see corals and the ecosystems they support endure, implementing targeted management should be our primary concern even as we encourage industrial nations to reduce their carbon emissions.

One of the best ways for us to save corals under climate pressure is to support changes by coastal fishing communities that use these ecosystems. In eastern Africa, the very communities that most rely on coral reef fish populations are already leading the way on this.

Mtwara Fishermen, Tanzania - Tim McClanahan
Mtwara Fishermen, Tanzania – Tim McClanahan

In Kenya, for instance, a consortium of communities have banded together in an effort to identify the most effective forms of fisheries management. Through a system of marine protected areas, fishing closures, and the banning of certain types of gear (fine-mesh fishing nets and traps), local communities have found they can conserve fish populations — an important factor in how corals cope with climate change.

We may not be able to save all reefs, and coastal nations and coral reef managers face some difficult decisions in the years to come. But resignation can create inaction when research, advocacy, and implementation of promising models for adaptation are most needed.

Powder Blue Tangs - Tim McClanahan
Powder Blue Tangs – Tim McClanahan

What we can do is to make sure conservation efforts pursue a strategy that targets improving the health of the most resistant coral reef systems around the world and supports communities in the efforts to conserve or adapt to impending change.

Our global energy portfolio will change slowly but key decisions and actions to protect coral reefs, which can come faster and cheaper, are imperative in the short term.

This Earth Day, let’s celebrate how such actions are already increasing the chances that coral ecosystems have a future.

 

The Author at Work
The Author at Work

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Dr. Tim McClanahan is a coral reef fisheries expert at the Wildlife Conservation Society.

 

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Wildlife Conservation Society
WCS saves wildlife and wild places worldwide through science, conservation action, education, and inspiring people to value nature.