The Sun Can Explain 70% or More of Global Warming, Says New Study

Few people realize that the popular narrative of overwhelmingly human-caused global warming, with essentially no contribution from the sun, hinges on a satellite dataset showing that the sun’s output of heat and light has decreased since the 1950s.

But if a different but plausible dataset is substituted, say the authors of a new study, the tables are turned and a staggering 70% to 87% of global warming since 1850 can be explained by solar variability. The 37 authors constitute a large international team of scientists, headed by U.S. astrophysicist Willie Soon, from many countries around the world.

The two rival datasets, each of which implies a different trend in solar output or TSI (total solar irradiance) since the late 1970s when satellite measurements began, are illustrated in the figure below, which includes pre-satellite proxy data back to 1850. The TSI and associated radiative forcing – the difference in the earth’s incoming and outgoing radiation, a difference which produces heating or cooling – are measured in units of watts per square meter, relative to the mean from 1901 to 2000.   

The upper graph (Solar #1) is the TSI dataset underlying the narrative that climate change comes largely from human emissions of greenhouse gases, and was used by the IPCC (Intergovernmental Panel on Climate Change) in its 2021 AR6 (Sixth Assessment Report). The lower graph (Solar #2) is a TSI dataset from a different satellite series, as explained in a previous post, and exhibits a more complicated trend since 1950 than Solar #1.

To identify the drivers of global warming since 1850, the study authors carried out a statistical analysis of observed Northern Hemisphere land surface temperatures from 1850 to 2018; the temperature record is shown as the black line in the next figure. Following the approach of the IPCC’s AR6, three possible drivers were considered: two natural forcings (solar and volcanic) and a composite of multiple human-caused or anthropogenic forcings (which include greenhouse gases and aerosols), as employed in AR6.   

Time series for the different forcings, or a combination of them, were fitted to the temperature record utilizing multiple linear regression. This differs slightly from the IPCC’s method, which used climate model hindcasts based on the forcing time series as an intermediate step, as well as fitting global land and ocean, rather than Northern Hemisphere land-only, temperatures.

The figure below shows the new study’s best fits to the Northern Hemisphere land temperature record for four scenarios using a combination of solar, volcanic and anthropogenic forcings. Scenarios 1 and 2 correspond to the Solar #1 and Solar #2 TSI time series depicted in the first figure above, respectively, combined with volcanic and anthropogenic time series. Scenarios 3 and 4 are the same without the anthropogenic component – that is, with natural forcings only. Any volcanic contribution to natural forcing usually has a cooling effect and is short in duration.

The researchers’ analysis reveals that if the Solar #1 TSI time series is valid, as assumed by the IPCC in AR6, then natural (solar and volcanic) forcings can explain at most only 21% of the observed warming from 1850 to 2018 (Scenario 3). In this picture, adding anthropogenic forcing brings that number up to an 87% fit (Scenario 1).

However, when the Solar #1 series is replaced with the Solar #2 series, then the natural contribution to overall warming increases from 21% to a massive 70% (Scenario 4), while the combined natural and anthropogenic forcing number rises from an 87% to 92% fit (Scenario 2). The better fits with the Solar #2 TSI time series compared to the Solar #1 series are visible if you look closely at the plots in the figure above.

These findings are enhanced further if urban temperatures are excluded from the temperature dataset, on the grounds that urbanization biases temperature measurements upward. The authors have also found that the long-term warming rate for rural temperature stations is only 0.55 degrees Celsius (0.99 degrees Fahrenheit) per century, compared with a rate of 0.89 degrees Celsius (1.6 degrees Fahrenheit) per century for rural and urban stations combined, as illustrated in the figure below.

Fitting the various forcing time series to a temperature record based on rural stations alone, the natural contribution to global warming rises from 70% to 87% when the Solar #2 series is used.

If the Solar #2 TSI time series represents reality better than the Solar #1 series used by the IPCC, this means that between 70% and 87% of global warming is mostly natural and the human-caused contribution is less than 30% – the complete opposite to the IPCC’s claim of largely anthropogenic warming.

Unsurprisingly, such an upstart conclusion has raised some hackles in the climate science community. But the three lead authors of the study have effectively countered their critics in lengthy, detailed rebuttals (here and here).

The study authors do point out that “it is still unclear which (if any) of the many TSI time series in the literature are accurate estimates of past TSI,” and say that we cannot be certain yet whether the warming since 1850 is mostly human-caused, mostly natural, or some combination of both. In another paper they remark that, while three of 27 or more different TSI time series can explain up to 99% of the warming, another seven time series cannot account for more than 3%.

Next: Challenges to the CO2 Global Warming Hypothesis: (9) Rotation of the Earth’s Core as the Source of Global Warming

Has the Mainstream Media Suddenly Become Honest in Climate Reporting?

Not so long ago I excoriated the mainstream media for misleading the public about perfectly normal extreme weather events. So ABC News’ August 14 article headlined “Why climate change can't be blamed for the Maui wildfires” came as a shock, a seeming media epiphany on the lack of connection between extreme weather and climate change.

But my amazement was short-lived. The next day the news network succumbed to a social media pressure campaign by climate activists, who persuaded ABC News to water down their headline by adding the word “entirely” after “blamed.” Back to the false narrative that today’s weather extremes are more common and more intense because of climate change.

Nevertheless, a majority of the scientific community, including many meteorologists and climate scientists, think that climate change was only a minor factor in kindling the deadly, tragic conflagration on Maui.

As ecologist Jim Steele has explained, the primary cause of the Maui disaster was dead grasses – invasive, nonnative species such as Guinea grass that have flourished in former Maui farmland and forest areas since pineapple and sugar cane plantations were abandoned in the 1980s. Following a wet spring this year which caused prolific grass growth, the superabundance of these grasses quickly became highly flammable in the ensuing dry season. The resulting tinderbox merely awaited a spark.

Three paragraphs later, the story quotes UCLA (University of California, Los Angeles) climate scientist Daniel Swain as saying:

We should not look to the Maui wildfires as a poster child of the link to climate change.

Swain’s statement was immediately followed by another from Abby Frazier, a climatologist at Clark University in Worcester, Massachusetts, wThat spark came from the failure of Maui’s electrical utility to shut off power in the face of hurricane-force winds. Numerous instances of blazes triggered by live wires falling on dessicated vegetation or by malfunctioning electrical equipment have been reported. Just hours before the city of Lahaina was devastated by the fires, a power line was actually seen shedding sparks and igniting dry grass.

Exactly the same conditions set off the calamitous Camp Fire in California in 2018, which was ignited by a faulty electric transmission line in high winds, and demolished Paradise and several other towns. While the Camp Fire’s fuel included parched trees as well as dry grasses, it was almost as deadly as the 2023 Maui fires, killing 86 people. The utility company PG&E (Pacific Gas and Electric Company) admitted responsibility, and was forced to file for bankruptcy in 2019 because of potential lawsuits.

Despite the editorial softening of ABC News’ headline on the Maui wildfires, however, the article itself still contains a number of statements more honest than most penned by run-of-the-mill climate journalists. Four paragraphs into the story, this very surprising sentence appears:

Not only do “fire hurricanes” not exist, but climate change can't be blamed for the number of people who died in the wildfires.

The term “fire hurricanes” refers to a term used erroneously by Hawaii’s governor when commenting on the fires.  ho commented that:

The main factor driving the fires involved the invasive grasses that cover huge parts of Hawaii, which are extremely flammable.

And there was more. All of which is unprecedented, to borrow a favorite word of climate alarmists, in climate reporting of the last few years that has routinely promoted the mistaken belief that weather extremes are worsening be­cause of climate change.

Is this the beginning of a new trend, or just an isolated exception?

Time will tell, but there are subtle signs that other mainstream newspapers and TV networks may be cutting back on their usual hysterical hype about extreme weather. One of the reasons could be the IPCC (Intergovernmental Panel on Climate Change) new Chair’s urging the IPCC to “stick to our fundamental values of following science and trying to avoid any siren voices that take us towards advocacy.” There are already a handful of media that endeavor to be honest and truly fact-based in their climate reporting, including the Washington Examiner and The Australian.

Opposing any move in this direction is a new coalition, founded in 2019, of more than 500 media outlets dedicated to producing “more informed and urgent climate stories.” The CCN (Covering Climate Now) coalition includes three of the world’s largest news agencies — Reuters, Bloomberg and Agence France Presse – and claims to reach an audience of two billion.

In addition to efforts of the CCN, the Rockefeller Foundation has begun funding the hiring of climate reporters to “fight the climate crisis.” Major beneficiaries of this program include the AP (Associated Press) and NPR (National Public Radio).

Leaving no doubts about the advocacy of the CCN agenda, its website mentions the activist term “climate emergency” multiple times and includes a page setting out:

Tips and examples to help journalists make the connection between extreme weather and climate change.

Interestingly enough, ABC News became a CCN member in 2021 – but has apparently had a change of heart since, judging from its Maui article.

Next: The Sun Can Explain 70% or More of Global Warming, Says New Study