Scientists have found yet another likely reason why the world should dramatically cut its greenhouse gas emissions.
Global warming could disrupt four-fifths of the world’s ocean ecosystems by 2050 if emissions keep climbing, threatening the main food source — fish — of about one in seven people globally, a new study found.
As ocean temperatures rise, and as waters absorb more carbon and turn acidic, marine life will struggle to adapt and may decline or die-off, according to research published Tuesday in the journal Nature.
On a slightly brighter note, however, reducing emissions would tangibly benefit organisms by giving them more time to adapt. Plant or coral species may develop heat-resistant characteristics, while schools of fish could build migrate to cooler waters near the Earth’s poles.
In either case, scientists still have very little idea how changes in ocean conditions will affect individual species, from whales and sharks to coral and phytoplankton.
“We don’t understand very well how quickly marine organisms can adapt to change,” said Stephanie Henson, the study’s lead author and a principal scientist at the British National Oceanography Center in Southhampton, England.
“We’re trying to understand what the impact these different stressors are going to have, but it’s really difficult because it’s so complex,” she said.
Henson and her colleagues used two potential emissions scenarios for their models of future ocean outcomes.
One, the world maintains its current pace of burning fossil fuels, clearing rainforests and building industrial farms.
Or two, countries achieve the goals set by the Paris Climate Agreement. The 2015 accord commits the world to limiting global warming to less than 2 degrees Celsius, or 3.6 degrees Fahrenheit, above preindustrial levels by 2100. It also sets an aspirational target of limiting warming to 1.5 degrees Celsius, or 2.7 degrees Fahrenheit.
In the first scenario, more than 80 percent of the world’s oceans will be negatively affected by ocean warming and ocean acidification in 33 years — compared to about 10 percent of the ocean today, the scientists found.
If countries meet the Paris targets, global warming would disrupt about two-thirds of the ocean.
That still might not sound like a dramatically different outcome. But Henson said it may be enough to give marine life a fighting chance.
“[Emissions] mitigation doesn’t stop the potential impacts, but perhaps it slows things down a little bit, so the organisms can adapt to the new conditions,” she said.