Scientists create new guide to save corals in a warming world

Nearly half of global coral has disappeared since 1980. And global climate change threatens to destroy what remains of these diverse and vital ecosystems, on which a quarter of all marine species and up to 1 billion people around the world depend on it.

Recognizing the enormity of the crisis, a team of scientists released Wednesday a new framework to help world leaders give corals a chance to survive. The report, drafted by a committee of national academies of science, engineering and medicine, evaluates a number of radical tools that could help strengthen reef resilience, and provides a blueprint for determining the best way to to intervene.

The report points out that human intervention could "save time" and be essential to ensure the persistence of reefs over the next century, but it can not be a substitute for reducing greenhouse gas emissions. greenhouse that warms the planet.

Resolving the climate crisis is "the only way for corals to thrive in the distant future," said Stephen Palumbi, chair of the committee and professor of marine biology at Stanford University, at a public meeting held Wednesday in Washington, DC.

Corals face many threats, including pollution, overfishing and damage from coastal development. However, the report focuses primarily on how to protect the reefs from bleaching, a phenomenon in which heat-stressed corals turn white after expelling their algae, which provide the bulk of the energy of coral polyps. If they are not allowed to recover without stress, the animals may perish. Massive bleaching episodes caused by above-average ocean temperatures in recent years have resulted in major deaths along the Great Barrier Reef in Australia and elsewhere.

The 170-page report is the second of two published by the Committee of 12 people, which held its first meeting in February 2018. The interim report, published in November, identified 23 radical intervention strategies, most experimental, could make corals more resistant to the effects of climate change. These tools include everything from relocation and genetic manipulation of coral species to the use of antibiotics through the spraying of salt water in the atmosphere to shade and cool the reefs.

According to the new analysis, some techniques are available at the moment, while others are not likely to be ready for years or even decades. For example, selective breeding and pre-exposure of corals to warmer water to enhance their heat resistance are proven techniques. But it may take decades before genetic manipulations and atmospheric shadows are developed and proven tools.

"Although all of these interventions involve risks, doing nothing increases every year," said Nancy Knowlton, committee member, reef biologist and former chair of marine science at the Smithsonian Institution, in a statement accompanying the meeting. publication of the report. Wednesday.

The Earth's temperature has already climbed 1.1 degrees Celsius above pre-industrial levels. If the planet heats up to 1.5 degrees Celsius (2.7 degrees Fahrenheit), the reefs could decline from 70 to 90 percentthe United Nations warned in a sobering report last year. This number could rise to 99% at 2 degrees Celsius of warming.

For nations and conservationists who wish to act, the report provides a detailed procedure for assessing the risks and benefits of implementing one or more interventions. The amount of degradation, water quality and location of a reef on other coral sites are among the many factors to consider in determining whether the tools are suitable for use, the committee concluded.

The report places particular emphasis on the engagement of local stakeholders, the long-term monitoring of reef health and the importance of an "adaptive" approach allowing leaders to change strategy as you go.

"The science of coral reef interventions is still young and particular environments can respond in different ways," Palumbi said in a press release.