Researchers behind a major study claiming the oceans of the Earth heat up faster than previously thought their work contained inadvertent mistakes that made their conclusions safer than they actually are.
Two weeks after the high-profile study was published in the journal Nature, its authors have submitted corrections to the publication. Scripp's Institution of Oceanography, home to several of the researchers involved, also noted the problems in the researchers' work and corrected a press release on its website, which previously claimed that the study describes how the ocean's ocean "has absorbed 60 percent more heat than previously thought."
"Unfortunately, we made mistakes here," says Ralph Keeling, climate researcher at Scripps, co-author of the study. "I think the most important lesson is that you work as quickly as possible to make mistakes when you find them."
The key issue, according to Keeling, was how the researchers handled the uncertainty in their measurements. As a result, the results are too much doubt to definitely support the paper's conclusion about how much heat the ocean has absorbed over time.
The central conclusion in the study – that the oceans maintain more energy when more heat is clamped in the Earth's climate system each year – is in line with other studies that have drawn similar conclusions. And it has not changed much despite the errors. But Keeling said that the authors' misbehavior means that there is actually a much greater margin of error in the results, which means that researchers can weigh in less security than they thought.
"I accept responsibility for what happened, because it is my role to ensure that such details have been conveyed," Keeling said.
The lead author of the study was Laure Resplandy of Princeton University. Other researchers were with institutions in China, Paris, Germany and U.S. National Center for Atmospheric Research and Geophysical Fluid Dynamics Laboratory.
"Maintaining the accuracy of the scientific report is of great importance for us as publishers and we acknowledge our responsibility to correct errors in papers we have published," said Nature in a statement to the post. "Questions related to this paper have come to the attention of nature and we look carefully at them. We take all the concerns about paper we have published very seriously and will issue an update when further information is available."
The original study, which appeared on October 31, derived a new method for measuring the amount of heat absorbed by the oceans. In essence, the authors measured the volume of gases, especially oxygen and carbon dioxide, which have released the ocean in recent decades and into the atmosphere it warms up. They discovered that warming "lies at the high level of past estimates" and suggested that global warming itself could be accelerated more.
The results, the authors wrote, suggest that there is less time than before thought to reduce greenhouse gas emissions. The study made great media attention, including from Posten.
But not long after publication, an independent British-based researcher, Nicholas Lewis, published a long blog post saying he had found a "big problem" with the research.
"As far as I can see, their method greatly underestimates the uncertainty," Lewis said in an interview on Tuesday, "and deepened significantly, almost 30 percent, the central estimate."
Lewis added that he tends to "read a large number of papers, and with a math and a physics background, I tend to look at them quite carefully and see if they are meaningful. And where they are not meaningful – with this it is quite obvious that It was not sensible – I'm looking at them deeper. "
Lewis has argued in previous studies and comments that climate researchers predict too much warming due to their dependence on computer simulations, and that current data from the planet itself indicate that global warming will be less serious than scared.
It is not clear if the authors agree with Lewis criticism, but Keeling said "we agree that there were problems in line with what he identified."
Paul Durack, a scientist at Lawrence Livermore National Laboratory in California, immediately said to acknowledge the error in the study "is the right approach for transparency".
But he added in an email: "This study, although there are further issues that arise now, confirms the long-standing result that the oceans have warmed over the observed record, and the warming has increased," he said.
Gavin Schmidt, director of the NASA Goddard Institute for Space Research, followed the growing debate on the study carefully on Twitter, saying that measurements of heat absorption in the oceans have been bedeviled with computer problems for some time – and debating new research in this area is difficult .
"Of course, you depend on your co-authors and reviewers to catch most problems, but things sometimes happen sometimes," Schmidt wrote in an email.
Schmidt and Keeling agreed that other studies also support a higher level of marine heat content than the Intergovernmental Panel on Climate Change, or the IPCC, in a milestone 2013 report.
Overall, Schmidt said the episode can be seen as a positive one.
"The key is not if mistakes are made, but how they are handled – and the answer from Laure and Ralph here is exemplary. No panic, but a careful reassessment of their work – despite a somewhat hostile environment," he wrote.
"So, plus one for a retrospective review, and plus one to the authors to rethink the entire calculation in a constructive way. We'll all become wiser."