Sep 9 2021Reviewed by Alex Smith
Researchers Yizhak Feliks, Justin Small and Michael Ghil have observed that the Earth’s global climate system fluctuates in 11-year and 3.5-year cycles. The 11-year near-periodicity resembles that of the solar cycle, which plays a major role in global warming, according to climate skeptics.
The findings in brief. Image Credit: TiPES/HP
However, the fluctuations between the Earth’s climate systems and the sun are contradictory, as per the study. The study, which was part of the European TiPES project coordinated from the University of Copenhagen, disproves the claim of climate skeptics about the major solar effect on recent climate evolution.
The study was published in the journal Climate Dynamics on July 15th, 2021.
A Search for Climate Tipping
The major objective of the study was to answer the question regarding the ability of large and complex climate models to offer a warning about climate tipping. Climate tipping may have occurred in past climates.
However, present large state-of-the-art IPCC climate models do not capture intrinsic low-frequency fluctuation, resulting in climate tipping. In terms of accuracy, the model may not be able to forecast the tipping in the climate system due to the current global warming.
Multichannel singular analysis was used to search for low frequency. This technique enables the identification of signals in a noisy environment, like picking out and isolating the sound of a single instrument from a large symphonic orchestra.
Two Frequencies
CESM involved the study of two large observational data sets and an advanced state-of-the-art climate model, demonstrating that large climate models have the ability to capture low-frequency oscillations. The model complies with observations in simulating the Earth’s two unique low-frequency modes. One with a span of 11 years and another with a span of 3.5 years.
The outcomes make it less likely that the lack of climate tipping in complicated climate models should be comprehended by the absence of low-frequency oscillations.
It’s great to find a decadal cycle in an IPCC-class model like CESM. The failure so far of finding intrinsic decadal variability in the high-end IPCC climate models cast doubts on their reliability. Our work with Yizhak Feliks and Justin Small indicates that these doubts are on their way to being resolved.
Michael Ghil, Ecole Normale Supérieure
Curves do not Fit
The observation of the controversial, 11-year cycle led to a comparison between the cycles of the climate system and the Sun, which can possibly explain global warming, from a climate skeptics perspective.
The near 11-year cycles were found in the large climate model and the two observational data sets in this study. However, the observations are thoroughly out of sync with that of the Sun. The curves do not fit. According to the current study, the fluctuation of the Sun plays very little role in the current global warming.
Solar-cycle effects on climate in general and global warming in particular have generated literally hundreds of articles in the scientific literature. No single paper, whether pro or con, will settle the debate for good. But our paper brings both a new point of view, from the synchronization theory of chaotic oscillators, and a possible resolution: Yes, there is a decadal climate cycle.
Michael Ghil, Ecole Normale Supérieure
“But it is intrinsic to the climate system and out of sync with the actual solar cycle. This lack of synchronicity argues quite vigorously for the physical effects of the solar cycle on climate being quite weak, and thus of no real consequence for global warming,” added Ghil.
The TiPES project is an EU Horizon 2020 interdisciplinary climate science project based on tipping points in the Earth system. A total of 18 partner institutions from more than 10 countries are collaborating.
TiPES is coordinated and led by The Niels Bohr Institute at the University of Copenhagen, Denmark, and the Potsdam Institute for Climate Impact Research, Germany. The TiPES project was financially supported by the European Horizon 2020 research and innovation program.
Journal Reference:
Feliks, Y., et al. (2021) Global oscillatory modes in high-end climate modeling and reanalyses. Climate Dynamics. doi.org/10.1007/s00382-021-05872-z.
Source: https://www.ku.dk/english/