Maintaining the status quo for greenhouse gas emissions could lead to the extinction of up to 90% of marine species, according to a study published Monday in the journal Nature Climate Change.
The researchers, led by ecologist Daniel Boyce of the Bedford Institute of Oceanography in Nova Scotia, examined some 25,000 species, including animals, plants, protozoa and bacteria. In a high-emissions scenario, they determined that nearly 90% of these species would be at high to critical risk across 85% of their distribution. This scenario implies a 3 to 5 degree Celsius increase in global ocean temperatures by the end of the century.
According to the study, around 10% of the ocean as a whole has ecosystems considered to be at high risk due to a combination of endemism, climate risk and the threat of local species extinction.
In addition to the threat this poses to biodiversity around the planet, the study findings present a major threat to people in the Global South, with the greatest danger to species native to low-income countries that are highly dependent on fishing in the tropics and subtropics, according to Boyce and his colleagues.
Meanwhile, reducing emissions — those that are in line with the Paris Climate Agreement’s goals of keeping warming below 2 degrees — would reduce the risk for around 98.2% of the species analyzed, according to the study.
The analysis is based on a combination of 12 climate risk factors. Boyce and his team grouped them into the broader categories of sensitivity, exposure, and adaptability.
“Our results show reduced climate risk to virtually all species and ecosystems under the low emissions scenario,” Boyce wrote in a blog post for Carbon Brief. “So sticking to the Paris Agreement targets would have substantial benefits for marine life, disproportionate climate risk to ecosystem structure, biodiversity hotspots, fisheries and low-risk countries. income being significantly reduced or eliminated.”