Has the Sun’s true role in global warming been miscalculated?

A new international study published in the scientific peer-reviewed journal, Research in Astronomy and Astrophysics, by 20 climate researchers from 12 countries suggests that the UN’s Intergovernmental Panel on Climate Change (IPCC) might have substantially underestimated the role of the Sun in global warming.

The article began as a response to a 2022 commentary on an extensive review of the causes of climate change published in 2021. The original review (Connolly and colleagues, 2021) had suggested that the IPCC reports had inadequately accounted for two major scientific concerns when they were evaluating the causes of global warming since the 1850s:

1. The global temperature estimates used in the IPCC reports are contaminated by urban warming biases.

2. The estimates of solar activity changes since the 1850s considered by the IPCC substantially downplayed a possible large role for the Sun.

On this basis, the 2021 review had concluded that it was not scientifically valid for the IPCC to rule out the possibility that global warming might be mostly natural.

The findings of that 2021 review were disputed in a 2022 article by two climate researchers (Dr. Mark Richardson and Dr. Rasmus Benestad) for two main reasons:

1. Richardson and Benestad (2022) argued that the mathematical techniques used by Connolly and colleagues (2021) were inappropriate and that a different set of mathematical techniques should have been used instead.

2. They also argued that many of the solar activity records considered by Connolly and colleagues (2021) were not up-to-date.

They suggested that these were the reasons why Connolly and colleagues (2021) had come to a different conclusion from the IPCC.

This new 2023 article by the authors of the 2021 review, has addressed both of these concerns and shown even more compelling evidence that the IPCC’s statements on the causes of global warming since 1850 are scientifically premature and may need to be revisited.

The authors showed that the urban component of the IPCC’s global temperature data shows a strong warming bias relative to the 98% of the planet that is unaffected by urbanization. However, they also showed that urbanized data represented most of the weather station records used.

While the IPCC only considered one estimate of solar activity for their most recent (2021) evaluation of the causes of global warming, Connolly and colleagues compiled and updated 27 different estimates that were used by the scientific community.

Several of these different solar activity estimates suggest that most of the warming observed outside urban areas (in rural areas, oceans, and glaciers) could be explained in terms of the Sun. Some estimates suggest that global warming is a mixture of human and natural factors. Other estimates agreed with the IPCC’s findings.

For this reason, the authors concluded that the scientific community is not yet in a position to establish whether the global warming since the 1850s is mostly human-caused, mostly natural or some combination of both.

The lead author of the study, Dr. Ronan Connolly, of the Center for Environmental Research and Earth Sciences (CERES-Science.com) described the implications of their findings,

“In scientific investigations, it is important to avoid beginning your analysis with your conclusions decided in advance. Otherwise you might end up with a false sense of confidence in your findings. It seems that the IPCC was too quick to jump to their conclusions.”

Another author of the study, Dr. Willie Soon, also of the Center for Environmental Research and Earth Sciences, explained:

“If the IPCC had paid more attention to open-minded scientific inquiry than trying to force a premature ‘scientific consensus’, then the scientific community would be a lot closer to having genuinely resolved the causes of climate change. Hopefully, our new analysis and datasets can help other scientists to get back to doing real climate science.”

This study reaches similar conclusions to another study that was recently published in a separate scientific peer-reviewed journal, Climate. This other study involved many of the same co-authors (led by Dr. Soon) and focused on a detailed case study of two solar activity estimates and two temperature estimates. It took a different approach to analyzing the problem but confirmed that varying the choice of solar activity and temperature estimates can lead to very different conclusions on the causes of global warming.

For media inquiries, please contact Dr. Ronan Connolly (Center for Environmental Research and Earth Sciences) at ronan@ceres-science.com or Dr. Willie Soon (Center for Environmental Research and Earth Sciences) at willie@ceres-science.com.

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Link to the study:

• R. Connolly, W. Soon, M. Connolly, S. Baliunas, J. Berglund, C.J. Butler, R.G. Cionco, A.G. Elias, V. Fedorov, H. Harde, G.W. Henry, D.V. Hoyt, O. Humlum, D.R. Legates, N. Scafetta, J.-E. Solheim, L. Szarka, V.M. Velasco Herrera, H. Yan and W.J. Zhang (2023). "Challenges in the detection and attribution of Northern Hemisphere surface temperature trends since 1850". Research in Astronomy and Astrophysics, 23(10), 105015. https://doi.org/10.1088/1674-4527/acf18e. (Open access).

• Link to accompanying datasets.

Links to other studies mentioned:

1. R. Connolly, W. Soon, M. Connolly, S. Baliunas, J. Berglund, C. J. Butler, R. G. Cionco, A. G. Elias, V. M. Fedorov, H. Harde, G. W. Henry, D. V. Hoyt, O. Humlum, D. R. Legates, S. Lüning, N. Scafetta, J.-E. Solheim, L. Szarka, H. van Loon, V. M. Velasco Herrera, R. C. Willson, H. Yan and W. Zhang (2021). How much has the Sun influenced Northern Hemisphere temperature trends? An ongoing debate. Research in Astronomy and Astrophysics, 21, 131. https://doi.org/10.1088/1674-4527/21/6/131. Supplementary Materials available at: https://doi.org/10.5281/zenodo.7088728.

2. M.T. Richardson and R.E. Benestad (2022). "Erroneous use of Statistics behind Claims of a Major Solar Role in Recent Warming". Research in Astronomy and Astrophysics, 22(12), 125008. https://doi.org/10.1088/1674-4527/ac981c. (pdf available here).

3. W. Soon, R. Connolly, M. Connolly, S.-I. Akasofu, S. Baliunas, J. Berglund, A. Bianchini, W.M. Briggs, C.J. Butler, R.G. Cionco, M. Crok, A.G. Elias, V.M. Fedorov, F. Gervais, H. Harde, G.W. Henry, D.V. Hoyt, O. Humlum, D.R. Legates, A.R. Lupo, S. Maruyama, P. Moore, M. Ogurtsov, C. ÓhAiseadha, M.J. Oliveira, S.-S. Park, S. Qiu, G. Quinn, N. Scafetta, J.-E. Solheim, J. Steele, L. Szarka, H.L. Tanaka, M.K. Taylor, F. Vahrenholt, V.M. Velasco Herrera and W. Zhang (2023). "The Detection and Attribution of Northern Hemisphere Land Surface Warming (1850–2018) in Terms of Human and Natural Factors: Challenges of Inadequate Data", Climate, 11(9), 179. https://doi.org/10.3390/cli11090179. (Open access).

4. IPCC (2021). "Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change". Cambridge: Cambridge Univ. Press. https://ipcc.ch