Record temperatures cause changes in ocean ecosystems: Marine scientist

ISTANBUL

Record high temperatures in the world are causing radical changes in ocean ecosystems, according to a marine scientist. 

According to the Climate Reanalyzer website of the University of Maine in the US and National Oceanic and Atmospheric Administration (NOAA) data, March 13 was the day when the daily average sea surface water temperature broke a record with 21.2C (70.16F).

The previous highest temperature, last August, was 21.1C (69.98F).

February was the warmest February on record, which also had an impact on sea surface water temperatures, according to a report by Copernicus, the EU’s climate change service.

While the global average sea surface water temperature in February was 21.06C (69.908F), it reached 21.09C (69.962F) daily by the end of the month.

The regions that warmed the most were the Atlantic Ocean and the central parts of the Pacific Ocean, the Indian Ocean, the Mediterranean and Black Sea basin, the Red Sea and the Persian Gulf.

NOAA marine scientist Gregory C. Johnson told Anadolu that the ocean water is on average 1 degree warmer than before the industrial revolution and that climate change is the main factor in the recorded extreme temperatures.

Mentioning how ocean surface temperature increases hit record levels in 2023, Johnson said: "I think the sea surface water temperature increased by roughly 0.25 degrees in 2023 compared to 2022, so last year, temperatures increased by the equivalent of about 20 years of warming.”

“While there were some variations from year to year due to El Nino and La Nina weather events, this was one of the biggest jumps in history,” he said. “But it's too early to say that temperatures will stay like this forever."

Johnson explained that the world experienced three consecutive La Nina winters before 2023, and that La Ninas mitigated the effects of global warming by keeping the planet cool, while this cooling effect disappeared in 2023, the beginning of the El Nino year.

- Other factors

Stating that such periodic fluctuations can be experienced from time to time, Johnson said scientists are discussing how various factors besides climate change may be the cause of this.

He pointed to low-sulfur diesel fuels used in maritime transportation as one of these factors because they are less harmful to the environment and human health.

Although these fuels are clean, they emit aerosols that reflect sunlight back into space and this may fuel the increase in sea surface temperatures, he stressed.

Sharing the view that the 2022 violent eruption of the Hunga Tonga Volcano in the Pacific Ocean could also be a cause of extreme temperatures in 2023, Johnson said: "This eruption pumped a lot of water vapor into the atmosphere. Of course, this is a small factor, but it still has a potential contribution."

He stressed that the weakening of the winds blowing over the oceans and the inability of the water on the ocean surface to mix with the deep water could also be a factor in the increase in surface water temperatures.

Explaining that NOAA has been measuring ocean temperatures at depths of up to 2 kilometers (over 1.24 miles) with various robotic technologies for about 20 years, Johnson said: "These data show us that not only the surface of the oceans but also the ocean depths are warming for kilometers.”

“Even the waters around Antarctica, which are known to be quite cold and absorb the temperatures in the oceans, have warmed,” he warned, adding: “As a result of greenhouse gases, 90% of the heat entering the climate systems mixes into the oceans."

- ‘Oxygen on the surface can't reach the depths’

Johnson also said the temperature increase in the oceans leads to changes in the ocean ecosystem.

"This warming in the oceans causes some animals in the oceans to head towards the poles, while others go deeper,” he said.

“The situation for creatures that cannot move, such as coral reefs, is different,” he said. “Coral reefs, which are important for the entire ecosystem, are seeing a major darkening.”

He noted: “It is possible to say that harmful algae such as 'red tides' have also increased due to warming.”

“A few years ago, we saw these harmful algae proliferating in the Seattle area where I live,” on the US Pacific coast, he said.

“Many seabirds and marine mammals died. It also affected various fisheries, some shellfish fisheries,” he added.

Saying that a layer forms on the surface due to the high temperatures on the ocean surface not being able to mix into the depths, Johnson underlined that because of this layer, the nutrients needed by plankton and found in the deep oceans cannot go up, and the oxygen on the surface cannot go down to the depths.

"As a result, the oxygen needed by creatures living in deep waters is decreasing,” he warned. “These creatures that want to meet their oxygen needs are trying to come to the surface, but unfortunately the water here is too hot for them."

Stating that these changes in the ocean do not only remain in the ocean but affect daily life, Johnson stressed: "Sea levels are rising and this means an increase in tidal flooding in areas where sea levels are rising, known as 'sunny day flooding'.”

"Warming seas are negatively affecting fisheries, and in many parts of the world, people's incomes depend on it,” he said. “What's more, the intensity of storms is increasing because the heat on the surface of the tropical oceans provides the energy for stronger hurricanes to spin up, making them more destructive.”

“So all of this is definitely affecting people's lives."

*Writing by Merve Berker