Recent research shows that a type of coral in Fiji may record changes in Pacific Ocean temperatures over the past 600 years.
Scientists report that Pacific Ocean temperatures have warmed over the centuries. This is evidenced by ocean heatwaves and widespread coral bleaching in recent years.
However, many believe that the Pacific has experienced years of extreme cold in the past, possibly even warmer than today’s temperatures. Nonetheless, this is difficult to prove as there are currently few records documenting such temperature changes, especially since these processes can span hundreds of years.
Nevertheless, a recent study by scientist Jack Marley and his colleagues may somewhat explain this process. This research was published in the journal Science Advances.
The researchers utilized a sample from a species of giant Diploastrea heliopora coral (also known as honeycomb coral).
Scientists sampling giant coral in Fiji in 1998. (Photo: IRD).
This specimen was discovered in 1998. Scientists collected the sample by drilling into the coral. They are currently analyzing this sample using modern scientific techniques.
Mr. Marley and his colleagues combined research data from this coral species with data from other coral species in the Fiji Islands to uncover clues about the temperature in the Fiji waters. During the 1990s, scientists collected extensive temperature data from weather buoys, satellites, and other devices.
This means that honeycomb coral can inform us about sea temperatures around Fiji from 1370 to 1997.
Coral as a Window to the Past
Large corals can live for many years, continuously forming calcium carbonate that accumulates in layers over the old skeletal framework. The living part of the coral is only a few millimeters on top. As new layers of calcium carbonate are added, they leave traces of the environmental conditions affecting the coral’s habitat on the old skeletal framework.
Specifically, Mr. Marley and his colleagues found two elements, strontium and calcium, in the coral skeleton. According to the news outlet The Conversation, these two elements serve as proxies for sea temperature. When there is less strontium compared to calcium in the coral skeleton, it indicates that when this coral layer was alive, the surrounding sea temperature was warm. Conversely, when strontium accumulates more than calcium in the coral skeleton, it means that when this layer of coral was alive, the surrounding sea temperature was cold.
The research data from the coral indicate that Pacific Ocean temperatures have fluctuated significantly over the centuries. This helps scientists gain a better understanding of climate change in the present and future.
The Pacific Ocean is closely linked to global climate change processes. It influences the transition from El Niño to La Niña phenomena. Accordingly, as ocean temperatures change, it leads to significant variations in rainfall and the development of storms.
This coral contains six centuries of environmental history. (Photo: IRD).
A Warning
The giant Diploastrea heliopora corals can preserve ocean temperature history for centuries. Notably, research from coral shows that the Pacific Ocean had a significant warm period from 1370 to 1553. During that time, the waters around Fiji were nearly as warm as they are today. This illustrates how the Pacific climate system changes naturally.
However, scientists indicate that data from this coral species can be combined with other temperature research data across the Pacific for a more comprehensive picture. When doing this, scientists realize that the warming across the Pacific over the past century is largely due to human-induced global warming.
In the past, some regions of the Pacific were warmer than others for one or two decades, and vice versa. However, that relationship is breaking down. The warming of sea temperatures now appears to be nearly ubiquitous across the Pacific.
This could lead to significant changes in rainfall patterns, droughts, and flooding cycles, as rainfall is often generated by water vapor evaporating over ocean areas.
But this warming is not a consistent phenomenon over the last 600 years. This indicates that the Pacific has warmed since the early 20th century and could lead to unprecedented changes in history.
Understanding these ocean temperature principles gives scientists more grounds to predict climate changes in the future.
The Pacific Ocean appears to be getting warmer. (Photo: SHUTTERSTOCK).
Mr. Marley’s team’s research indicates that the ocean surrounding Fiji is the warmest it has been in over 650 years. These changes could lead to more extreme weather, such as prolonged droughts and intensified tropical storms, significantly impacting millions of people living in the region.
This study also highlights the important role corals play in recording ocean temperature changes; however, the future of corals is also threatened by rising sea temperatures. Therefore, conserving these giant coral reefs is crucial.
