On the September 21 broadcast of his nationally syndicated radio show, Rush Limbaugh selectively read from a year-old article to falsely suggest that a 2004 study by the Max Planck Institute for Solar System Research found that an increase in solar brightness is the sole cause of global warming. In fact, the article, which appeared in the London Telegraph on July 18, 2004, specifically noted that the study's lead author did not believe increased solar brightness was responsible for the dramatic rise in global temperatures over the past 20 years; according to the parent organization of the group that conducted the study, solar brighteness “plays only a minor role in the current global warming.” As Media Matters for America has noted, Limbaugh has a history of promoting the idea that humans are not the cause of global warming.

After falsely claiming that the Telegraph article was published “today [September 21],” Limbaugh quoted only from the year-old article's misleading opening paragraphs.

From the September 21 broadcast of The Rush Limbaugh Show:

LIMBAUGH: A story from the UK Telegraph today:

"The Truth About Global Warming. Global warming has finally been explained: the earth is getting hotter because the sun is burning more brightly than at any time during the past 1,000 years, according to new research.

"A study by Swiss and German scientists suggests that increasing radiation from the sun is responsible for recent global climate changes.

“Dr. Sami Solanki, Director of the renowned Max Planck Institute for Solar System Research in Germany, who led the research, said, 'The sun has been at its strongest over the past 60 years and may now be affecting global temperatures.' ”

Has to be the case, because there's global warming on Mars.

But Limbaugh did not read several portions of the article that contradict its misleading first few paragraphs, which suggest that only the sun is to blame for global warming. For example, Limbaugh did not inform readers that according to the Telegraph, “Dr Solanki said that the brighter Sun and higher levels of 'greenhouse gases,' such as carbon dioxide, both contributed to the change in the Earth's temperature but it was impossible to say which had the greater impact.”

Noting that 1997, 1998, and 2002 were the warmest years since global temperatures were first recorded in 1860, the Telegraph also reported that Solanki “says that the increased solar brightness over the past 20 years has not been enough to cause the observed climate changes.”

In addition, the Telegraph cited Dr. David Viner, a senior research scientist at the University of East Anglia's climatic research unit. While Viner did acknowledge that variations in solar brightness appear to have an effect on global temperatures, he also pointed out that the Planck Institute study actually found that solar brightness levels had remained relatively constant after 1980, even as temperatures rose dramatically.

Moreover, the Max Planck Society (MPS) -- of which the Planck Institute is a part -- issued an August 2, 2004, press release that confirms Viner's interpretation of the Planck Institute study. The press release noted in its subtitle that according to the study, “solar activity affects the climate but plays only a minor role in the current global warming.” The press release continued:

These scientific results therefore bring the influence of the Sun on the terrestrial climate, and in particular its contribution to the global warming of the 20th century, into the forefront of current interest. However, researchers at the MPS have shown that the Sun can be responsible for, at most, only a small part of the warming over the last 20-30 years. They took the measured and calculated variations in the solar brightness over the last 150 years and compared them to the temperature of the Earth. Although the changes in the two values tend to follow each other for roughly the first 120 years, the Earth's temperature has risen dramatically in the last 30 years while the solar brightness has not appreciably increased in this time.

A graph on the Plank Institute website illustrates the divergence between changes in solar brightness (irradiance) and global temperature increases since 1980: