According to recent research, about 35.6% to 95% of the 20th-century ocean surface climates—determined by surface water temperature, pH, and the concentration of the mineral aragonite—might perish by 2100.
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This is based on the advancement of greenhouse gas emissions in the first half of the 21st century. The research was published in the Scientific Reports journal. The observations also indicate that about 10.3% to 82% of the global ocean might encounter surface climates that never existed before.
Katie Lotterhos and co-workers designed ocean climates worldwide for three time periods—the early 19th century (1795–1834), the late 20th century (1965–2004), and the late 21st century (2065–2104). The researchers matched these modeled climates across different locations employing two emission scenarios, RCP 4.5 and RCP 8.5.
As per these scenarios, the amount of greenhouse gases discharged during the 21st century either peaks in 2050 trailed by a slow increase, or peaks in 2100 followed by a slow increase, respectively.
With the help of the comparisons, the researchers were able to reveal the ocean climates from the 19th and 20th centuries that may not be found any longer in the 21st century (disappearance), and climates that may arise in the 21st century that did not exist during the 18th and 20th centuries (novel climates).
The researchers demonstrated that even though the ocean climates did not change considerably between the 19th and 20th centuries, by 2100, 10%–82% of the ocean surface may encounter novel climates with increased temperatures, high acidic pH, and low saturation of aragonite.
Aragonite is a mineral used by corals and other marine organisms to develop shells. As per the RCP 4.5 scenario, 35.6% of surface ocean climates might perish by 2100 and rise to 95% as per the RCP 8.5 scenario.
The researchers conclude that even though certain marine species at present keep pace with the varying ocean climates by dissipating to new habitats, this might not be possible if the present ocean climates perish, pushing species to either adapt quickly to new climates or disappear.
Lotterhos, K. E., et al. (2021) Novel and disappearing climates in the global surface ocean from 1800 to 2100. Scientific Reports. doi.org/10.1038/s41598-021-94872-4.