- A new study suggests that global temperature rise has already crossed the 1.5°C threshold and could exceed 2°C by the end of the 2020s.
- By analyzing a sponge species found in the Caribbean Sea and examining 19th-century temperature records, researchers obtained data confirming the past temperature change of the oceans.
- But some scientists question these findings and criticize the complexity of the oceans and data calibration.
According to a recently published study, global temperature rise has already exceeded the critical 1.5°C threshold, and according to current projections, global temperature may exceed the 2°C climate change increase threshold by the end of the 2020s. The study states that global surface temperatures have increased by 1.7°C above pre-industrial averages. But other scientists question the findings, arguing there are flaws in the study.
Global warming reaching 2°C increases the likelihood of catastrophic and irreversible climate collapse. In the 2015 Paris Agreement, nearly 200 countries pledged to limit global temperature increases ideally to 1.5°C and safely below 2°C. “The big picture is that the global warming clock has been brought forward by at least a decade to reduce emissions to minimize the risk of dangerous climate change,” said lead author Malcolm McCulloch, a coral reef expert at the University of Western Australia. said.
One of the main problems in climate science is determining the pre-industrial baseline before the burning of fossil fuels. Scientists use natural temperature data in corals, ice cores, and tree rings to sort through inaccurate records from the past.
Scientists still cannot agree on the amount of post-industrial warming. According to an analysis based on the US National Oceanic and Atmospheric Administration’s 2023 data set, the Earth warmed by 1.34°C above the 1850-1900 average, but data from the UK Met Office shows that this increase was 1.54°C.
Ocean Temperature Analysis with Sponges
A species of sponge called Ceratoporella nicholsoni, found in the Caribbean Sea, has become a valuable resource for scientists researching temperature records of the 19th century. This type of sponge absorbs strontium and calcium carbonate from seawater, adding layers to its limestone shells over centuries. Researchers can measure 300-year-old temperature records by examining the strontium and calcium ratios in the skeletons of these sponges.
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Their results from analysis of sponges collected from deep waters show that global warming began in the 1860s, approximately forty years earlier than predicted by the Intergovernmental Panel on Climate Change (IPCC). Researchers found that by 1990, global temperatures had increased by 0.9°C compared to the pre-industrial period. This increase was greater than the 0.4°C warming predicted by the IPCC. According to the study, if current warming rates continue, a 2°C warming will be reached by the end of the 2020s, and a 2.5°C warming is expected to occur by 2040.
New Climate Change Research Sparks Controversy
Some climate scientists question the results of a new study. Some researchers suggest that the oceans were well mixed and that the water temperatures recorded by sponges came from the depths mostly due to the influence of sunlight. Others argue that the ocean is still temperature unstable and has a complex structure.
“Skepticism is warranted here,” said Michael Mann, director of the Center for Earth System Science at the University of Pennsylvania. “In my opinion, it is not credible to argue against current data based on historical records of sponges in a region.” says. “It is not correct to draw general conclusions from the Caribbean to the Earth’s oceans,” said Camille Parmesan, an ecologist at the University of Texas at Austin and Coordinating Lead Author of the IPCC’s 6th Assessment Report. says. David Thornalley, Professor of Ocean and Climate Science at University College London, criticized the researchers’ decision to extrapolate sponge data to global sea surface temperatures.
“The study fails to support global claims with solid evidence and largely fails,” said Jochem Marotzke, Professor of Climate Science and Director of the Max Planck Institute for Meteorology in Germany. “To make global-scale predictions from this tiny piece of ocean is completely incredible.” says. Citing a 2018 paper, researchers argue that Caribbean sea surface temperature trends are proportional on a global scale. Although the results are controversial, scientists state that this study can contribute to global climate knowledge in a period of rapid climate change.
Compiled by: Ayça Ayaz