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.

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