Climate scientists from the Technical University of Munich (TUM) and the Potsdam Institute for Climate Impact Research (PIK) have pinpointed three main sources of uncertainty. First, predictions depend on assumptions about the underlying physical mechanisms and future human actions, which may be overly simplistic, leading to significant errors. Second, long-term, direct climate system observations are rare, and the data may not adequately represent the Earth system components. Third, historical climate data is incomplete, with significant data gaps, especially for the distant past, and the methods used to fill these gaps can introduce statistical errors in predicting potential tipping times.
To illustrate their findings, the authors examined the AMOC, a critical ocean current system. Historical data suggested a collapse could occur between 2025 and 2095. However, the new study found that the uncertainties are so substantial that these predictions are unreliable. Using different fingerprints and data sets, predicted tipping times for the AMOC ranged from 2050 to 8065, even if the mechanistic assumptions were accurate. Knowing that the AMOC might tip within a 6000-year window is not practically useful, highlighting the complexity and uncertainty involved in such predictions.
The researchers conclude that while predicting climate tipping points is appealing, the reality is fraught with uncertainties. The current methods and data are insufficient for the task. "Our research is both a wake-up call and a cautionary tale," says lead author Maya Ben-Yami. "There are things we still can't predict, and we need to invest in better data and a more in-depth understanding of the systems in question. The stakes are too high to rely on shaky predictions."
Although the study by Ben-Yami and colleagues shows that we cannot reliably predict tipping events, the possibility of such events cannot be dismissed. The authors emphasize that statistical methods are still effective in indicating which parts of the climate have become more unstable. This includes not only the AMOC but also the Amazon rainforest and ice sheets.
"The large uncertainties imply that we need to be even more cautious than if we were able to precisely estimate a tipping time. We still need to do everything we can to reduce our impact on the climate, first and foremost by cutting greenhouse gas emissions. Even if we can't predict tipping times, the probability for key Earth system components to tip still increases with every tenth of a degree of warming," concludes co-author Niklas Boers.
Research Report:Uncertainties too large to predict tipping times of major Earth system components from historical data
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Technical University of Munich
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