Latest research and modeling projects a 59% probability of the Atlantic Meridional Overturning Circulation (AMOC) collapsing before 2050. The study was made public early but has not yet been officially published so should be considered preliminary.
The collapse time is estimated between 2037-2064 (10-90% CI) with a mean of 2050 and the probability of an AMOC collapse before the year 2050 is estimated to be 59±17%. Probability Estimates of a 21st Century AMOC Collapse
This is consistent with the development of an early warning signal for AMOC collapse published earlier this year. Measurements of this signal indicate that the AMOC is on the pathway to collapse. https://www.science.org/doi/10.1126/sciadv.adk1189
The collapse of the AMOC would dramatically alter the global ecology and do so quickly. It probably won’t be pretty.
Probably the most useful tip-off that it’s wrong or simply a meaningless scare headline. It’s always the end of the world. But this time its REALLY IS an emergency! The IPCC is way way more hopeful about the future.
Meanwhile OpEd in yesterdays WSJ points out that many climate based predictions proved to be false. Polar bear population increased. Australias Great Barrier Reef thrived. Pacific Islands expected to flood grew from additional sand. Predictions are used to frighten the public. Not of much value.
Yes, and that is utterly typical for predictions regarding hugely complex systems such as Earth’s climate. What is left out – ALWAYS – in such critiques are all the utterly unknown unpredicted effects that will be showing up. The closest we are seeing so far are the shifts in North Atlantic current flows.
Not quite true. If you see it has a 59% probability of happening in a given time period, it can be a black swan. Nassim Nicholas Taleb coined the phrase so his definition should be the definitive one. He lists three criteria for a Black Swan event.
An event that is unpredictable.
A black swan event results in severe and widespread consequences.
After the occurrence of a black swan event, people will rationalize the event as having been predictable (known as hindsight bias).
Unpredictable is not the same as inconceivable. Claiming the Yankees have a 59% probability of getting to the World Series is not a prediction. One cannot predict if and when the AMOC will collapse, but they can estimate the likelihood of its collapse for a given time period. Insurance companies make large profits doing estimates of that type for lesser disasters. They don’t predict that Miami will be flooded on Aug 3, 2024. They estimate the probability of it happening. Big difference.
Same with many WSJ financial predictions. Yet people still apparently read the WSJ and are influenced by what they read.
But again, the OP link is not a prediction. It is more like what actuaries do for insurance companies. They use math and data to calculate the risks of a possible event. Estimates of climate risks are apparently sufficiently valid in the eyes of insurance companies to either pull out of places like Florida and California or significantly raise rates.
This is a journalism issue, not a scientific one. Show me the scientific paper describing a worse case climate scenario that didn’t discuss all the potential complicating factors. Read the linked paper and tell us whether you believe it is guilty of this error.
The author of the op-ed, Bjorn Lomborg is not scientist, he’s an economist. I’d be very careful of taking what says at face value. Taking the part in bold, data show the perimeters of the Great Barrier Reef are expanding. But that says nothing about the health of the reef. A tree can grow even if it is dying. In fact, the Great Barrier Reef is in serious trouble.
Similarly, consider this from the article:
Today, killer heat waves are the new climate horror story. In July President Biden claimed “extreme heat is the No. 1 weather-related killer in the United States.”
He is wrong by a factor of 25
I found it odd the president would make such a big mistake in a prepared speech. So I Googled around and it seems that indeed, extreme heat is the biggest weather related killer. Data source is NOAA.
I clicked his link to see his data source, and his source is a post he made on Twitter. And if you click through, he supports his arguments by relying heavily on his Twitter posts and his own op-ed columns. That might be not be the best way to do things.
Highest coral cover in central, northern Reef in 36 years www.sciencedaily.com/releases/2022/08/220803162710.htm The northern and central Great Barrier Reef have recorded their highest amount of coral cover since the Australian Institute of Marine Science (AIMS) began monitoring 36 years ago. However, average coral cover in the southern region decreased due to ongoing crown-of-thorns starfish outbreaks.
“There is an emerging sense that the oceans do have some resilience, and while they are changing in response to climate change, we don’t see evidence that marine heat waves are wiping out fisheries,” said Alexa Fredston, the lead author of the study…
The analysis included 248 marine heat waves with extreme sea bottom temperatures during this period [1993-2019]. The researchers were surprised to find that marine heat waves in general don’t show major adverse effects on regional fish communities…
Overall, they found that the effects of marine heat waves aren’t distinguishable from the natural variability in these ecosystems.
Climate scientists from the Technical University of Munich (TUM) and the Potsdam Institute for Climate Impact Research (PIK) have identified three primary sources of uncertainty.
First, predictions rely on assumptions regarding the underlying physical mechanisms, as well as regarding future human actions to extrapolate past data into the future. These assumptions can be overly simplistic and lead to significant errors.
Second, long-term, direct observations of the climate system are rare and the Earth system components in question may not be suitably represented by the data. Third, historical climate data is incomplete…
To illustrate their findings, the authors examined the AMOC, a crucial ocean current system. Previous predictions from historical data suggested a collapse could occur between 2025 and 2095. However, the new study revealed that the uncertainties are so large that these predictions are not reliable.
Using different fingerprints and data sets, predicted tipping times for the AMOC ranged from 2050 to 8065 even if the underlying mechanistic assumptions were true…
The researchers conclude that while the idea of predicting climate tipping points is appealing, the reality is fraught with uncertainties. The current methods and data are not up to the task.
One can define prediction however one wants. But I think there is a significant difference between a risk assessment and a prediction.
An estimate of the probability of an AMOC collapse based on physics and statistics is a risk assessment. It describes the likelihood of a collapse but does not predict if or when the AMOC will collapse.
You left out some important stuff (surprise!). Here is what these authors conclude:
In conclusion, we showed that the uncertainties discussed in this work are too large to allow for reliable estimates of the tipping time of major Earth system tipping elements, including the AMOC, the polar ice sheets, or tropical rainforests, based on extrapolating results from historical data.
The AMOC paper I linked was aware of and directly responded to your link in the discussion (12 refers to your link):
Although there has been criticism regarding the estimation of tipping times from observational data and the various assumptions inherent in the estimation procedures [12], our method presented here offers a more physically based approach to identify optimal locations for EWS and establishing a lower bound of AMOC tipping times.
There is no indication that the authors of the first paper (your link) disagree with the new methodology of the second paper (the OP), which after all hasn’t even been published yet.
A deeper dive that will be boring to most…
Drbob’s link claims that previous predictions of the AMOC collapse are flawed because of large uncertainties in the historical data and the statistical methods used. The OP link generally agrees that those are legitimate problems, so it used a different approach that is not reliant on historical reconstructions. They found that one of the more advanced climate models projects an AMOC collapse. They identified from the model the most important physical factors and their locations. These represent the signals for an AMOC collapse, the canaries in the bird cage if you will. They then used current real-world observations to determine how close we are from those collapse metrics.
In other words, past predictions of AMOC doom were based on extrapolating from the historical data. Drbob’s link says the historical data ain’t good enough for that. The OP link avoids the historical data problem by identifying metrics in specific locations that presage an AMOC collapse in models and seeing how close the real world is to those values.
