An interactive world atlas can help conservation efforts

As warming ocean temperatures threaten the existence of coral reefs, scientists at the National Heart for Atmospheric Analysis (NCAR) have successfully used a simulation very high-resolution computer science of ocean circulation to identify possible “thermal refugia” where these biodiverse ecosystems are more likely to survive.

The research team has published an interactive and freely available online global atlas (https://ncar.github.io/coral-viz/) with the locations of these areas, where ocean dynamics and cooler waters occur. combine to provide possible refuges for coral reefs. said NCAR scientist Scott Bachman, who led the new study, published in the journal Frontiers in Marine Science. “We invite researchers to visit our website, identify where the refuges are, and then go out and observe the health of the reefs.”

The research was supported by the US Nationwide Science Basis, which is the sponsor of NCAR. The study was co-authored by scientists from the University of Tasmania and the University of Auckland.

Cooler Water Waves

Climate change poses such a threat to coral reefs around the world that the majority are expected to disappear within three decades, with warming ocean waters bleaching reefs and leaving behind them lifeless skeletons. The loss of coral reefs has profound ramifications for the environment and society. They are home to almost a third of marine species and support hundreds of millions of people around the world. Reefs generate an estimated global economic value of 000 000 billion dollars per year, and the The safety they provide to shorelines from storms and floods is worth billions of dollars each year, according to Joan Kleypas, NCAR scientist and co-author of the study.

However, scientists have found that some reefs do better than others. In some areas of the ocean, for example, colder water, lifted from ocean depths by subterranean oscillations called internal ocean gravity waves, can blanket reefs and shield them from increased heat.

“These gravity waves are everywhere, and in particular conditions they can bring cooler water near the area of ​​the ocean where the reefs are,” said Bachman said. “You need powerful waves with large amplitudes to collide with physical obstructions, like a seamount, to force the waves to rise.”

Scientists have understood for some time that this gravity wave phenomenon exists in certain places. For example, a combination of the tides and deep basins of the Coral Triangle – a sea area that includes the waters of Indonesia, Malaysia, the Philippines and other neighboring countries – creates ailments that promote gravity waves. bringing cooler water to the surface area. But it has been difficult to pinpoint every place on the globe where similar conditions might exist, in part because gravity waves may not bring water to the area and therefore cannot be identified by satellites.

Without the ability to observe thermal refugia from space, scientists are left with computer modeling as a tool to identify them on a global scale. The main obstacle for models, however, is scale. Coral reefs are relatively small compared to the vastness of the ocean, and running a simulation at high enough resolution over the entire world to capture how gravity waves interact with a specific reef requires massive computer resources.

However, such a simulation exists. NASA’s Ocean Circulation and Climate Estimation (ECCO) project simulated the entire ocean at a resolution of about 2 kilometers and recorded data at hourly time intervals, sufficiently frequency to accurately capture the behavior of internal gravity waves. To perform the analysis needed to identify thermal refugia, Bachman downloaded 400 terabytes of staggering data from the ECCO project.

“This style of study is not uncommon locally,” Bachman said. “But it’s uncommon on a regional scale, and so far it’s never been done on a global scale.”

The atlas that The result offers some hope, according to Kleypas, who conducted pioneering research on the effects of climate change on coral reefs.

“The coral reefs are not well and we are all going through a period of mourning,” Kleypas said. “This study sheds light on the reasons for hope. We’re not saying this atlas will solve everything, but it can help us be smarter in our approach to conserving the reefs that have the best chance of survival.”

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