El Niño combines with climate change for multiplied impact on seawater temperatures

By Gulseli Kenarli

ISTANBUL (AA) - An El Niño weather event, combined with climate change, has had a multiplier effect as it has pushed seawater temperatures to record highs, according to a Turkish researcher.

Data from the EU-linked Copernicus Climate Change Service has revealed that nine out of the first 10 months on record when global sea surface temperatures surpassed the 1991-2020 average transpired during the most recent El Niño period, with one instance occurring during 2016's El Nino phase.

According to an analysis by the Institute of Marine Sciences at Middle East Technical University (METU), the average sea water temperature in the Mediterranean during the El Niño period, which started in June last year and ended in April this year, was 23.06C (73.5F).

This figure was 21.04C (69.8F) in the previous El Niño period of 2014-2016, 20.98C (69.7F) in 1997-1998 and 20.25C (68.4F) in 1982-1983.

In the Aegean Sea, the sea water temperature was recorded as 19.97C (67.9F) as during the last El Niño period was 18.11C (64.5F) in 2014-2016, 18.03C (64.4F) in 1997-1998 and 17.51C (63.5F) in 1982-1983.

In the Marmara Sea, these figures were recorded as 17.21C (62.9F), 14.72C (58.4F), 15.18C (59.3F) and 15.10C (59.1F) from the last El Nino.

In the Black Sea, which follows a similar course to the Marmara Sea, the seawater temperature in the last El Niño period was 17.36C (63.2F), while in the past El Niño periods, it was measured as 14.47C (58F), 15.10C (59.1F) and 14.67C (58.4F), respectively.

- ‘Our seas are alarming’

Baris Salihoglu, director of the METU Institute of Marine Sciences, told Anadolu that the El Niño period is behind us, but its effects are still continuing, and with the combination of this weather phenomenon with climate change, extreme temperatures have started to be seen.

Emphasizing that this situation affects not only the temperature of the sea but also the ecosystem structure and the services it provides, he said: “When we compare this El Niño with the previous very strong ones, the seawater temperatures we have reached are beyond all of them -- record temperatures.”

“When this was combined with climate change, the overall effect was very strong,” he stressed. “It had a multiplier effect and raised temperatures to numbers we have never seen before.”

Pointing out that while the sea surface water temperatures in the Mediterranean had reached a maximum of 21C (69.8F) in previous El Niño periods, this time they reached 23C (73.4F), he said.

“The last El Niño we saw was in 2014-2016, not even 10 years ago, and we’ve seen an increase of 2 degrees in the Mediterranean.

“The Aegean is in a similar situation. There is an increase of close to 2 degrees.”

“Increases in the Marmara Sea and the Black Sea are above 2 degrees,” he said. “There is a situation here that really makes us say 'Our seas are alarming'.”

“The climate is changing, and with the addition of El Niño, we have seen temperatures we have never seen before.

“The effects of these on the ecosystem will be very big, and we will see them,” he warned.

- ‘It is not possible for the ecosystem to adapt’

Salihoglu indicated that the regions most affected by the temperature increase in the seas are the Eastern Mediterranean and the Eastern Black Sea, saying the warming affects the deep seas in different ways.

“We can no longer see the cold interlayer in the Black Sea. There is a similar situation in the Mediterranean. The warming is reflected in the deep sea,” he asserted.

“But we cannot see this as clearly as in the Black Sea,” he said.

“In the Marmara Sea, it is very clear because the waters in the deep sea come from the Mediterranean Sea and the change in the deep sea here is much faster, so we see a serious temperature increase in the deep sea in Marmara.”

Explaining that there are currently many pressures on the seas such as pollution, invasive species and hunting, Salihoglu said it is not possible for the ecosystem to adapt to such sudden temperature changes.

He noted that when talking about species and biodiversity in the seas, not only fish should not be considered, but the whole ecosystem -- starting with phytoplankton that photosynthesizes -- should be addressed.

He emphasized that there can be serious changes in microscopic plants such as phytoplankton during temperature increases.

“There can be harmful algal blooms or, as we saw during the mucilage period, the proliferation of the species that cause it can occur,” he said.

“In the Black Sea and the Mediterranean Sea, we see periodic explosions of toxic algae species,” he said. “We see increases in jellyfish.”

“The change in fish species is tremendous. Half of the fish species currently found on the Mediterranean coast are invasive species.

“Since these species are already adapted to warm waters, they immediately adapted here,” he said, noting “there is already an eroded habitat and ecosystem.”

“Native and economic species will experience changes in their spawning and natural migration periods due to increasing temperatures,” he said.

- Migration of marine species ‘changes the ecosystem as a whole’

Underlining that fishing is the activity that erodes the ecosystem the most, Salihoglu further mentioned that phytoplankton, zooplankton, fish and even mammals are affected.

He said that sea creatures migrate to the north with the increase in temperature.

“I don't think migration to the north is a solution for species in closed seas like us,” he said. “It is more clearly observed in the oceans, but this is not a solution either.”

“Because the migrating species become new species for the regions they go to and the ecosystem changes completely,” he said.

“There will definitely be migrations in seas like ours, such as the Mediterranean and the Black Sea, but they mean a change in the ecosystem and will not have a positive outcome.”

Saying that El Niño, which is a natural event, cannot be prevented and that measures should be taken regarding climate change, Salihoglu emphasized: “Rising temperatures due to climate change are the work of humans. We need to prevent this.”

“We need to reduce carbon emissions,” he said. “We have not been able to keep the temperature rise to 1.5 degrees, but we need to keep it to at least 2 degrees.”

“Climate change is a reality, and it is not easy to reverse it. The solution for the seas is to reduce other pressures.

“We need to reduce fishing and pollution pressure to make marine and terrestrial ecosystems climate resilient,” he said.

“Pollution is not only a problem of Marmara, but of all our seas,” he said. “We need to end the use of harmful fishing gear such as trawls and support ecosystems that are struggling with climate pressure.”

“We need to eliminate these pressures so that ecosystems can resist climate change. This is the solution.”

- The months with the highest temperatures above the average and the temperature differences are listed as follows as per data from the EU-linked Copernicus Climate Change Service:

YEAR/MONTH

TEMPERATURE DIFFERENCE

(ACCORDING TO 1991-2020 AVERAGE – CELSIUS)

2016/02 0.68C (over 33.2 degrees Fahrenheit)

2023/07 0.72C

2023/08 0.70C

2023/09 0.93C

2023/10 0.85C

2023/11 0.85C

2024/01 0.69C

2024/02 0.80C

2024/03 0.72C

2024/04 0.66C

*Writing by Merve Berker