Noam Vogt-Vincent, University of Hawaii Tropical reefs might look like inanimate rock, but these colorful seascapes are built by tiny jellyfish-like animals called corals. While adult corals build solid structures that are firmly attached to the sea floor, baby corals are not confined to their reefs. They can drift with ocean currents over great distances to new locations that might give them a better chance of survival. The underwater cities that corals construct are home to about a quarter of all known marine species. They are incredibly important for humans, too, contributing at least a trillion dollars per year in ecosystem services, such as protecting coastlines from wave damage and supporting fisheries and tourism. Unfortunately, coral reefs are among the most vulnerable environments on the planet to climate change. Since 2023, exceptionally warm ocean water has been fueling the planet’s fourth mass coral bleaching event on record, causing widespread mortality in corals around the world. This kind of harm is projected to worsen considerably over the coming decades as ocean temperatures rise.

I am a marine scientist in Hawaii. My colleagues and I are trying to understand how coral reefs might change in the future, and whether new coral reefs might form at higher latitudes as the tropics become too warm and temperate regions become more hospitable. The results lead us to both good and bad news.

Corals can grow in new areas, but will they thrive?

Baby corals can drift freely with ocean currents, potentially traveling hundreds of miles before settling in new locations. That allows the distribution of corals to shift over time. Major ocean currents can carry baby corals to temperate seas. If new coral reefs form there as the waters warm, these areas might act as refuges for tropical corals, reducing the corals’ risk of extinction.

Scientists know from the fossil record that coral reef expansions have occurred before. However, a big question remains: Can corals migrate fast enough to keep pace with climate change caused by humans? We developed a cutting-edge simulation to find the answer. Field and laboratory studies have measured how coral growth depends on temperature, acidity and light intensity. We combined this information with data on ocean currents to create a global simulation that represents how corals respond to a changing environment – including their ability to adapt through evolution and shift their ranges. Then, we used future climate projections to predict how coral reefs may respond to climate change. We found that it will take centuries for coral reefs to shift away from the tropics. This is far too slow for temperate seas to save tropical coral species – they are facing severe threats right now and in the coming decades.

Underwater cities in motion?

Under countries’ current greenhouse gas emissions policies, our simulations suggest that coral reefs will decline globally by a further 70% this century as ocean temperatures continue to rise. As bad as that sounds, it’s actually slightly more optimistic than previous studies that predicted losses as high as 99%. Our simulations suggest that coral populations could expand in a few locations this century, primarily southern Australia, but these expansions may only amount to around 6,000 acres (2,400 hectares). While that might sound a lot, we expect to lose around 10 million acres (4 million hectares) of coral over the same period. In other words, we are unlikely to see significant new tropical-style coral reefs forming in temperate waters within our lifetimes, so most tropical corals will not find refuge in higher latitude seas. Even though the suitable water temperatures for corals are forecast to expand poleward by about 25 miles (40 kilometers) per decade, corals would face other challenges in new environments. Our research suggests that coral range expansion is mainly limited by slower coral growth at higher latitudes, not by dispersal. Away from the equator, light intensity falls and temperature becomes more variable, reducing growth, and therefore the rate of range expansion, for many coral species. It is likely that new coral reefs will eventually form beyond their current range, as history shows, but our results suggest this may take centuries.

Some coral species are adapted to the more challenging environmental conditions at higher latitudes, and these corals are increasing in abundance, but they are much less diverse and structurally complex than their tropical counterparts. Scientists have used human-assisted migration to try to restore damaged coral reefs by transplanting live corals. However, coral restoration is controversial, as it is expensive and cannot be scaled up globally. Since coral range expansion appears to be limited by challenging environmental conditions at higher latitudes rather than by dispersal, human-assisted migration is also unlikely to help them expand more quickly. Importantly, these potential higher latitude refuges already have rich, distinct ecosystems. Establishing tropical corals within those ecosystems might disrupt existing species, so rapid expansions might not be a good thing in the first place.

No known alternative to cutting emissions

Despite enthusiasm for coral restoration, there is little evidence to suggest that methods like this can mitigate the global decline of coral reefs. As our study shows, migration would take centuries, while the most severe climate change harm for corals will occur within decades, making it unlikely that subtropical and temperate seas can act as coral refuges. What can help corals is reducing greenhouse gas emissions that are driving global warming. Our study suggests that reducing emissions at a faster pace, in accordance with the Paris climate agreement, could cut the coral loss by half compared with current policies. That could boost reef health for centuries to come. This means that there is still hope for these irreplaceable coral ecosystems, but time is running out. Noam Vogt-Vincent, Postdoctoral Fellow in Marine Biology, University of Hawaii This article is republished from The Conversation under a Creative Commons license. Read the original article.

Mariah Meek, Michigan State University and Karrigan Börk, University of California, Davis It wouldn’t make much sense to prohibit people from shooting a threatened woodpecker while allowing its forest to be cut down, or to bar killing endangered salmon while allowing a dam to dry out their habitat. But that’s exactly what the Trump administration is proposing to do by changing how one word in the Endangered Species Act is interpreted: harm. For 50 years, the U.S. government has interpreted the Endangered Species Act as protecting threatened and endangered species from actions that either directly kill them or eliminate their habitat. Most species on the brink of extinction are on the list because there is almost no place left for them to live. Their habitats have been paved over, burned or transformed. Habitat protection is essential for their survival.

As an ecologist and a law professor, we have spent our entire careers working to understand the law and science of helping imperiled species thrive. We recognize that the rule change the Trump administration quietly proposed could green-light the destruction of protected species’ habitats, making it nearly impossible to protect those endangered species.

The legal gambit

The Endangered Species Act, passed in 1973, bans the “take” of “any endangered species of fish or wildlife,” which includes harming protected species. Since 1975, regulations have defined “harm” to include habitat destruction that kills or injures wildlife. Developers and logging interests challenged that definition in 1995 in a Supreme Court case, Babbitt v. Sweet Home Chapter of Communities for a Great Oregon. However, the court ruled that the definition was reasonable and allowed federal agencies to continue using it. In short, the law says “take” includes harm, and under the existing regulatory definition, harm includes indirect harm through habitat destruction.

The Trump administration is seeking to change that definition of “harm” in a way that leaves out habitat modification. This narrowed definition would undo the most significant protections granted by the Endangered Species Act.

Why habitat protection matters

Habitat protection is the single most important factor in the recovery of endangered species in the United States – far more consequential than curbing direct killing alone. A 2019 study examining the reasons species were listed as endangered between 1975 and 2017 found that only 17% were primarily threatened by direct killing, such as hunting or poaching. That 17% includes iconic species such as the red wolf, American crocodile, Florida panther and grizzly bear. In contrast, a staggering 81% were listed because of habitat loss and degradation. The Chinook salmon, island fox, southwestern willow flycatcher, desert tortoise and likely extinct ivory-billed woodpecker are just a few examples. Globally, a 2022 study found that habitat loss threatened more species than all other causes combined. As natural landscapes are converted to agriculture or taken over by urban sprawl, logging operations and oil and gas exploration, ecosystems become fragmented and the space that species need to survive and reproduce disappears. Currently, more than 107 million acres of land in the U.S. are designated as critical habitat for Endangered Species Act-listed species. Industries and developers have called for changes to the rules for years, arguing it has been weaponized to stop development. However, research shows species worldwide are facing an unprecedented threat from human activities that destroy natural habitat. Under the proposed change, development could be accelerated in endangered species’ habitats.

Gutting the Endangered Species Act

The definition change is a quiet way to gut the Endangered Species Act. It is also fundamentally incompatible with the purpose Congress wrote into the act: “to provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved [and] to provide a program for the conservation of such endangered species and threatened species.” It contradicts the Supreme Court precedent, and it would destroy the act’s habitat protections.

Secretary of the Interior Doug Burgum has argued that the recent “de-extinction” of dire wolves by changing 14 genes in the gray wolf genome means that America need not worry about species protection because technology “can help forge a future where populations are never at risk.” But altering an existing species to look like an extinct one is both wildly expensive and a paltry substitute for protecting existing species.

The administration has also refused to conduct the required analysis of the environmental impact that changing the definition could have. That means the American people won’t even know the significance of this change to threatened and endangered species until it’s too late, though if approved it will certainly end up in court.

The ESA is saving species

Surveys have found the Endangered Species Act is popular with the public, including Republicans. The Center for Biological Diversity estimates that the Endangered Species Act has saved 99% of protected species from extinction since it was created, not just from bullets but also from bulldozers. This regulatory rollback seeks to undermine the law’s greatest strength: protecting the habitats species need to survive. Congress knew the importance of habitat when it passed the law, and it wrote a definition of “take” that allows the agencies to protect it. Mariah Meek, Associate Professor of Integrative Biology, Michigan State University and Karrigan Börk, Professor of Law, University of California, Davis This article is republished from The Conversation under a Creative Commons license. Read the original article.