Study off Fiji

Southwest Pacific never as warm as now in 600 years

The sea near the Fiji Islands has never been as warm as it is today in more than 600 years. This is shown by a new study.

(Bild: AFP)

The sea near the Fiji Islands in the southwest Pacific has never been as warm as it is today for more than 600 years. This is the result of a study published in the journal "Science Advances". 

The data is "further proof of the unprecedented warming of the western Pacific", according to the Mainz-based Johannes Gutenberg University (JGU).

Honeycomb coral provides a glimpse into the past
The reef-forming honeycomb coral (Diploastrea heliopora) made it possible to look into the climate past. It can become very old and, according to JGU, grows an average of three to six millimetres per year. The skeleton of such corals stores the climate changes of past centuries.

The honeycomb coral provides insights into the past.

(Bild: picturedesk.com/ETHAN DANIELS / Science Photo Library)

Specifically, the researchers looked at an approximately two-metre-long core from such a coral, and more precisely at the ratio of strontium to calcium. The age of the respective layer was determined using the so-called uranium-thorium dating method - precisely this contribution was made by the Institute of Geosciences at Mainz University.

2022 warmest year since 1370
Roughly speaking, the method looks at how strongly contained uranium isotopes have radioactively decayed and been transformed into thorium, which allows conclusions to be drawn about the age. The analysis of coral data from 1370 to 1997, supplemented by water temperature measurements for 26 years, showed that 2022 was the warmest year in the Pacific region since 1370.

The southwestern Pacific plays a central role in the regulation of global climate patterns such as the El Niño-Southern Oscillation weather phenomenon. This is a coupled circulation system of ocean and atmosphere in the tropical Pacific. According to experts, strong and moderate El Niño events contribute to warming and increase the average global surface temperature and can influence high and low pressure systems, winds and precipitation.

Concerns about climate catastrophes
The researchers of the Coral Project report that, according to current climate simulations, the development over the course of the 21st century is likely to lead to further drought or heavy rainfall, depending on the position in the Pacific, and thus - if no countermeasures are taken - to "adverse effects for inhabitants of the endangered Pacific islands and their ecosystems".