Ocean surface climates may disappear by 2100: study

Around a third all of the carbon pollution created since the Industrial Revolution has been absorbed by the seas.
Research published Thursday shows that up to 95% of Earth's oceans will be affected by the end of this century if humanity doesn't reduce its carbon emissions.

Ocean surface climates are defined by the ocean's surface temperature, acidity, and the level of the mineral aragonite, which many marine animals use for their bones and shellsupport the vast majority.

Around a third all of the carbon pollution created since the Industrial Revolution has been absorbed by the seas.

However, with atmospheric CO2 levels rising at an unprecedented rate in at least three millions years, it is possible that the ocean's surface climates will become less welcoming to the species it hosts.

Researchers based in the USA wanted to determine what impact carbon pollution had on the ocean surface since mid-1800s. They also predicted the effects of carbon pollution through 2100.

They used three time periods to model global ocean climates: the early 19th Century (1795-1834), the late 20th Century (1965-2004), and the latter part of the 21st Century (2065-2014).

The models were then run through two emission scenarios. The first known as RCP4.5envisions an increase in greenhouse gas emissions up to 2050, followed by a gradual decrease over the course of the century.

The second scenarioRCP8.5is "business as usual", where emissions will continue to rise for the next 80 years.

The researchers published their findings in Nature Scientific Reports. They found that the RCP4.5 scenario would result in 36 percent of ocean surface conditions being lost by 2100.

This figure is higher under the scenario of high emissions.

The team also discovered that although ocean surface climates did not change much during the 20th Century, climates could be changing by 2100. This means that up to 82 per cent of the ocean's surface may have climates unlike any other time in recent history.

These seas are more acidic, hotter and contain fewer minerals that are essential for sea life to thrive.

Katie Lotterhos from Northeastern University's Marine Science Center was the lead author of the study. She said that changes in ocean composition caused by carbon pollution will likely have an impact on all surface species.

She said that species that are not adaptable to a changing climate will need to adapt to new conditions.

"A climate where the temperature and chemical composition of water are common today will be uncommon or absent in future."

Options that are less attractive

Although surface species have been able to move about in oceans to avoid being in acidic or anomalously warm areas, the Thursday study suggests that their options might be limited by near-uniform heating and acidification.

Lotterhos stated that "already, many marine species has shifted their ranges due to warmer waters."

"The diversity of species found in one region will continue to change and shift rapidly over the next decades.

She stated that governments should monitor shifting patterns in the marine surface species.

However, it is essential that the oceans of the world stop producing the acidification and heating gases that cause their destruction.

Lotterhos stated that "without (emissions mitigation), novel and disappearing climates will be widespread throughout the globe by 2100."

Continue reading Rising sea levels and melting glaciers are irreversible. But we can slow them down.

More information: Lotterhos K.E., Lruson J. LQ. Jiang, LQ. New and changing climates in the global ocean surface from 1800 to 2100 Sci Rep 11, 15535 (2021). www.nature.com/articles/s41598-021-94872-4 Journal information: Scientific Reports Lotterhos, K.E., Lruson, .J. Jiang, LQ. New and changing climates in the global ocean surface from 1800 to 2100.11 (15535 2021). doi.org/10.1038/s41598-021-94872-4

2021 AFP

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