Gulf Stream map [image credit: RedAndr @ Wikipedia]
The lead and co-author have clearly different views on this:
Lead author: “While we can definitively say this weakening is happening, we are unable to say to what extent it is related to climate change or whether it is a natural variation.”
Co-author: “It saddens me to acknowledge, from our study and so many others, and from recent record-breaking headlines, that even the remotest parts of the ocean are now in the grip of our addiction to fossil fuels.”
What have headlines got to do with science research?
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The Gulf Stream transport of water through the Florida Strait has slowed by 4% over the past four decades, with a 99% certainty that this weakening is more than expected from random chance, according to a new study.
The Gulf Stream — which is a major ocean current off the U.S. East Coast and a part of the North Atlantic Ocean circulation — plays an important role in weather and climate, and a weakening could have significant implications, says Science Daily.
“We conclude with a high degree of confidence that Gulf Stream transport has indeed slowed by about 4% in the past 40 years, the first conclusive, unambiguous observational evidence that this ocean current has undergone significant change in the recent past,” states the journal article, “Robust weakening of the Gulf Stream during the past four decades observed in the Florida Straits,” published in Geophysical Research Letters.
The Florida Straits, located between the Florida Keys, Cuba, and The Bahamas, has been the site of many ocean observation campaigns dating to the 1980s and earlier. “This significant trend has emerged from the dataset only over the past ten years, the first unequivocal evidence for a recent multidecadal decline in this climate-relevant component of ocean circulation.”
The Gulf Stream affects regional weather, climate, and coastal conditions, including European surface air temperature and precipitation, coastal sea level along the Southeastern U.S., and North Atlantic hurricane activity. “Understanding past Gulf Stream changes is important for interpreting observed changes and predicting future trends in extreme events including droughts, floods, heatwaves, and storms,” according to the article.
“Determining trends in Gulf Stream transport is also relevant for clarifying whether elements of the large-scale North Atlantic circulation have changed, and determining how the ocean is feeding back on climate.”
“This is the strongest, most definitive evidence we have of the weakening of this climatically-relevant ocean current,” said Chris Piecuch, a physical oceanographer with the Woods Hole Oceanographic Institution, who is lead author of this study.
The paper does not conclude whether the Gulf Stream weakening is due to climate change or to natural factors, stating that future studies should try to identify the cause of the weakening.
“While we can definitively say this weakening is happening, we are unable to say to what extent it is related to climate change or whether it is a natural variation,” Piecuch said. “We can see similar weakening indicated in climate models, but for this paper we were not able to put together the observational evidence that would really allow us to pinpoint the cause of the observed decline.”
. . .
The study builds on many earlier studies to quantify long-term change in Gulf Stream transport. While the weakening found in the current study is consistent with hypotheses from many previous studies, Piecuch noted that the current study is “water-tight” and is “the first unequivocal evidence of a decline.”
Piecuch said that the finding of definitive evidence of the weakening of the Gulf Stream transport of water “is a testament to long-term ocean observing and the importance of sustaining long ocean records.”
The current study, which is part of a bigger six-year project funded by the National Science Foundation to make new measurements of the Gulf Stream at the Florida Straits, emphasizes the importance of having long-term observations, he said. “The more subtle that the change is that you are looking at, the longer is the observational record that you need to be able to tease that subtle change out of an observational time series.”
Full article here.
via Tallbloke’s Talkshop
September 28, 2023 at 03:36AM
Iowa Climate Science Education 