Warming oceans have forced tens of thousands of marine species to abandon their tropical homes along the equator and relocate to cooler waters, a new study reveals.
Researchers, led by the University of Auckland, found a mass exodus of nearly 50,000 species including fish, mollusks, birds and corals that have moved poleward since 1955.
In other words, scientists say, species that can move are moving to escape warming surface temperatures that currently average 68F (20C).
The findings show that rising temperatures are making tropical regions unbearable for native species, but these creatures are relocating to subtropical waters that are also warming.
The study is just another stark warning of how climate change is impacting the creatures that also call our planet home.
Senior author Mark Costello, a professor of marine biology at the University of Auckland, told AFP: ‘Global warming has been changing life in the ocean for at least 60 years.’
‘Our findings show a drop of about 1,500 species at the equator.
‘This will continue throughout the century, but the pace will depend on how we reduce—or not—greenhouse gas emissions.’
The team found a total of 48,661 species have moved south over three 20-year periods up to 2015.
The number of species attached to the seafloor, including corals and sponges, remained somewhat stable in the tropics between the 1970s and 2010, according to the study.
However, some have been found beyond the tropics, suggesting they are also trying to escape warming waters.
Sebastian Ferse, an ecologist at the Leibniz Centre for Tropical Marine Research who was not involved with the study, said: ‘In geological history, this has occurred in the blink of an eye.
‘To see such changes occurring so rapidly is something quite alarming.’
‘One of the big questions is `Will coral reefs as ecosystems and corals as species be able to move north or south enough fast enough to adjust to a changing climate?´
The team found that poleward migration was more pronounced north of the equator, where oceans have warmed more quickly than in the southern hemisphere.
David Schoeman, a professor of ecology at Nelson Mandela University in Port Elizabeth, South Africa, said: ‘The ‘missing’ tropical species are likely following their thermal habitat as subtropical waters warm.’
Fossil records show that the same thing happened 140,000 years ago, the last time global surface temperatures were as hot as they are now.
The mass exodus is not just affecting the ecosystem, but also some 1.3 billion people living in coastal tropics who rely on these marine animals for a source of food.
A recent review article in Nature estimated that the maximum catch potential of tropical fish stocks in so-called exclusive economic zones—200 nautical miles (370 kilometers) from the coast—would decline 40 percent by mid-century if global warming continues unabated.
Stuart Pimm, a conservation scientist at Duke University not involved in the study, said: ‘Such changes ‘can have a really huge impact on some of the most vulnerable human communities around the planet.’
The latest study echoes the finds from a team at the University of Exeter that found at least 25 percent of marine mammals are classified as threatened.
The paper, published in March, also notes that 98 percent of all marine mammal species are at some level of risk in 56 percent of the ocean.
Following this detailed review, researchers determined the shocking declines are a result of climate change, fisheries, pollution and other forms of human activity.