Nature has issued a retraction of a published study analyzing how much heat Earth’s oceans absorb, citing concerns over certain measurements of data. However, the overall findings of the study remain the same.
The 2018 study found that the scientific community had previously underestimated the amount of heat absorbed by Earth’s oceans in recent decades, IFLScience reported at the time. This could mean that the planet is more sensitive to fossil-fuel emissions than once thought.
Researchers at Scripps Institute of Oceanography and Princeton University wrote in Nature that the ocean had absorbed 60 percent more heat over the last 25 years than a figure released by the United Nations Intergovernmental Panel on Climate Change (IPCC) at the time. (Note: The IPCC has since released an updated report on the implications of global climate change.)
"Shortly after publication, arising from comments from Nicholas Lewis, we realized that our reported uncertainties were underestimated owing to our treatment of certain systematic errors as random errors,” wrote the original study authors in a retraction note published on September 25.
Additionally, the study authors noticed several smaller issues in the analysis of uncertainty. They found that correcting the issues did not substantially change the estimate of ocean warming but did lead to four times the amount of uncertainties previously reported. Uncertainty is a scientific concept that explains variability in the data. This can be due to both the limits of technology and natural variability that are inherent in nature, according to Vision Learning. Repeating an experiment or analysis will produce a variety of results that scatter around a central point or value that, when considered as a whole, yields a generalized conclusion.
"Because of these weaker implications, the Nature editors asked for a Retraction, which we accept,” wrote the study authors. “Despite the revised uncertainties, our method remains valid and provides an estimate of ocean warming that is independent of the ocean data underpinning other approaches."
To reach their 2018 conclusions, the researchers used high-precision oxygen and carbon dioxide measurements that were taken around the world from robotic sensors known as Argo to infer ocean temperature increases. Previous estimates assumed the oceans take up around 90 percent of excess energy produced as the Earth warms. But if that number is actually far higher, the study authors note that greenhouse gas emissions are trapping more heat than realized.
“Imagine if the ocean was only 30 feet deep,” wrote lead author Laure Resplandy in a statement at the time. “Our data shows that it would have warmed by 6.5℃ (11.7℉) every decade since 1991. In comparison, the estimate of the last IPCC assessment report would correspond to a warming of only 4℃ (7.2℉) every decade.”
The study authors say that a revised paper with corrected uncertainties will be submitted to another journal.