Novel Global Ocean Surface Climate Likely to Emerge, Says Study

According to recent research, about 35.6% to 95% of the 20^th-century ocean surface climates—determined by surface water temperature, pH, and the concentration of the mineral aragonite—might perish by 2100.

Image Credit: shutterstock.com/Don Pablo

This is based on the advancement of greenhouse gas emissions in the first half of the 21^st 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 19^th century (1795–1834), the late 20^th century (1965–2004), and the late 21^st 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 21^st 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 19^th and 20^th centuries that may not be found any longer in the 21^st century (disappearance), and climates that may arise in the 21^st century that did not exist during the 18^th and 20^th centuries (novel climates).

The researchers demonstrated that even though the ocean climates did not change considerably between the 19^th and 20^th 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.

Journal Reference:

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.