Climate change has warmed up our planet’s water bodies, which a new study published in the journal Science says can make these aquatic habitats unlivable for 60% of fish species by 2100, if temperatures keep rising at unprecedented rates.
At the root of this struggle is reproduction — both saltwater and freshwater fish are the most sensitive to rising temperatures as spawning adults, and as embryos. At these life stages, fish use more energy and oxygen to survive, which unfortunately is already depleting fast in rapidly heating water bodies.
Scientists studied almost 700 species of fish — all either economically or ecologically essential to sustaining an aquatic ecosystem that feeds billions of people around the world — and found them to be most vulnerable when in reproductive or embryonic stages of their life cycle. Some ocean species of fish, scientists say, might evolve to move to cooler waters, possibly farther away from civilization, but freshwater fish — often heavily relied upon for fishing and as a source of protein — who are restricted to rivers and lakes, could find themselves struggling to procreate, and therefore, multiply and survive.
Since pre-industrial times, the planet’s temperature has slowly risen by just over 1 degree Celsius. In order to stop this rise, governments all over the world have been committing to halting this global rise at 1.5 degrees Celsius, in order to stay the devastation caused by global warming. If successful, this could limit the damage to aquatic life, to affect only 10% of fish species, researchers found. But a recent United Nations report shows this 1.5 degree Celsius limit is unlikely to hold; the world is on track to record a 3 degree Celsius spike by 2030. If we keep moving at this rate, scientists fear a worst-case scenario playing out for marine wildlife, which can increase the rate of their endangerment six-fold.
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Looking at environmental reports from just earlier this year, the worst-case scenario is increasingly seeming more probable. In January, a study published in the journal Advances in Atmospheric Sciences showed how 2019 was a record-setting year for ocean warming, and that the world’s oceans were heating at a rate that was akin to dropping five Hiroshima bombs in them every second.
“The Hiroshima atom-bomb exploded with an energy of about 63,000,000,000,000 Joules,” Lijing Cheng, the January paper’s lead author, told CNN. “I did a calculation … the amount of heat we have put in the world’s oceans in the past 25 years equals to 3.6 billion Hiroshima atom-bomb explosions … There are no reasonable alternatives aside from the human emissions of heat trapping gases to explain this heating.”
The only way to alter this trajectory, marine biologists stress, is to instill a renewed, dedicated, and persistent focus on reducing emissions as the only way to stop this from driving hundreds of species into extinction.
