Ever since an asteroid wiped out the dinosaurs – along with half of all other creatures on Earth – life in the ocean has not been so endangered. Heated waters are creatures that cook in their own habitats. Many species are slowly suffocating as oxygen passes through the seas. Even populations that have survived the ravages of overfishing, pollution and habitat loss are struggling to survive amid accelerating climate change. If humanity’s greenhouse gas emissions continue to rise, according to a new study released on Thursday, about a third of all marine animals could be extinct within 300 years. The findings, published in the journal Science, reveal a possible mass extinction beneath the waves. The oceans have absorbed one-third of carbon and 90 percent of the excess heat generated by humans, but their enormous extent and prohibitive depths mean that scientists are just beginning to understand what creatures face there. However, the study by Princeton University scientists Justin Penn and Curtis Deutsch also highlights how much marine life could still be saved. If people take swift action to limit the use of fossil fuels and restore degraded ecosystems, researchers say, it could reduce potential extinctions by 70%. “This is a landmark document,” said Malin Pinsky, an Rutgers University biologist who did not contribute to the work. “If we are not careful, we are heading towards a future that I think for all of us at the moment would seem quite damn good. “It’s a very important wake-up call.” How ocean protection can save species and fight climate change The world has already warmed up more than 1 degree Celsius (1.8 degrees Fahrenheit) since pre-industrial times and last year the oceans contained more heat than anywhere else since records began six decades ago. These rising ocean temperatures are shifting the boundaries of the comfort zones of sea creatures. Many flee north in search of cooler waters, causing “extinction” —or local extinction — of common species. Polar creatures that can only survive in the coldest conditions can soon be found with nowhere to go. Species that cannot be easily moved in search of new habitats, such as fish that depend on specific coastal wetlands or geological formations on the seabed, will be more likely to become extinct. Using climate models that predict species behavior based on simulated organism types, Deutsch and Penn found that the number of eradication or local extinction of specific species increases by about 10 percent with every 1 degree Celsius of heating. The researchers tested their models using them to simulate a mass extinction at the end of the Permian period, when catastrophic overheating caused by volcanic eruptions wiped out about 90 percent of life on Earth. Because the models successfully reproduced events 250 million years ago, scientists were confident in their predictions of what might happen 300 years from now. Research by Penn and Deutsch found that most animals can not afford to lose much more than 50 percent of their habitat – beyond that number, the species leads to an irreversible decline. In the worst case scenario, the losses would be equivalent to the five worst mass disappearances in Earth history. These changes have already begun to unfold. In the 1980s, a heat wave in the Pacific wiped out a small, silverfish called a Galapagos girl from the waters of Central and South America. A hot spot off the coast of Uruguay has led to massive shellfish deaths and extensive changes in fishermen’s catches. Japan’s salmon fishing has plummeted as sea ice receded and warmer, depleted water flooded the area. The risk of warming is exacerbated by the fact that warmer waters are beginning to lose dissolved oxygen – although higher temperatures speed up the metabolism of many marine organisms, so they need more oxygen to survive. The ocean contains only one-60th oxygen from the atmosphere. even less in warmer regions where water molecules are less able to hold precious oxygen than to gush back into the air. As global temperatures rise, this reservoir shrinks even more. The warming of the sea surface also causes the ocean to stratify into separate layers, making it more difficult for warmer, oxygenated water from above to mix with the colder depths. Scientists have documented expanding “shadow zones” where oxygen levels are so low that most lives can not survive. Deoxygenation is one of the biggest climate threats to marine life, said Deutsch, one of the study co-authors. Most species can expend a little extra energy to cope with higher temperatures or to adapt to increasing acidity. Even some corals have found ways to protect their skeletons from calcium carbonate from corrosion in more acidic waters. “But there is no price that organisms can pay to get more oxygen,” Deutsch said. “They’re just stuck.” Mankind’s greatest ally against climate change is the Earth itself This climate-driven marine death is just one piece of a wider biodiversity crisis affecting the entire globe. A recent report by the Intergovernmental Panel on Climate Change found that overheating has already contributed to the extinction of at least 400 species. A separate UN commission has found that an additional 1 million species are at risk of extinction as a result of overexploitation, habitat destruction, pollution and other human disturbances in the natural world. A comprehensive new assessment published Wednesday in the journal Nature found that more than 20 percent of reptile species could disappear. Turtles and crocodiles are most at risk, with more than half of the groups at least vulnerable to extinction in the near future. The implications for reptile-based communities for food, pest management, culture and other services can be profound. “If we start mixing up the ecosystems and the services they provide, it will have a negative impact,” said co-author Neil Cox, director of the biodiversity assessment unit at the International Union for Conservation of Nature. “I think the threats to biodiversity are as serious as climate change, we just underestimate them.” Seeds of hope: How nature inspires scientists to fight climate change However, the two crises are closely linked, added Blair Hedges, an evolutionary biologist at Temple University, who contributed to the reptile assessment. Climate change may accelerate the death of populations that have already been destabilized by habitat degradation or hunting. Ecosystems that lose key species may be less able to pull carbon out of the atmosphere or protect themselves from climate change. Researchers have highlighted the plight of Virgin Gorda, a miniature reptile that lives in damp soil pockets on the slopes of the Caribbean hills. The creation of national parks on the islands where the gecko is located helped prevent the loss of habitat that could have condemned the species. But now his house is drying up from climate change, once again increasing the range of extinction. “If you have multiple threats άζονται they work together, often even when you think one of them is under control, then the other turns out to be even more threatening,” Hetzes said. While the danger to animals – and humans – is unquestionably appalling, Pinsky, Rutgers’ biologist, urged us not to succumb to despair. In a Science Analysis accompanying the Penn and Deutsch report, he and Rutgers ecologist Alexa Fredston compared marine animals to canaries in a coal mine, warning humanity of invisible forces – such as the dangerous accumulation of carbon dioxide and loss of oxygen in the ocean – which also threatens our ability to survive. If humans can take action to preserve the wildlife of the oceans, we will end up saving ourselves. “It’s scary, but it’s also invigorating,” Pinsky told The Post. “What we are doing today and tomorrow and the rest of this year and next has really important consequences,” he added. This is not a “once in a lifetime” moment, but perhaps “once in a lifetime”. Sign up for the latest climate and environment news delivered every Thursday
