The sun reflects off a rock pool at Tamarama Beach in Sydney.
Solar UV radiation absorbed by oxygen has not contributed to global warming, experts say. Image by Tracey Nearmy/AAP IMAGES

Global warming theory crumbles under scientific scrutiny

Zathia Bazeer December 21, 2022
WHAT WAS CLAIMED

Global warming is caused by oxygen absorbing UV radiation, not the greenhouse effect.

OUR VERDICT

False. Global warming is the result of rising CO2 levels in the atmosphere increasing the greenhouse effect.

The greenhouse effect has long been recognised as the process behind earth’s rapid warming.

But one researcher reckons the whole thing is a hoax. Instead, he has said warming is actually caused by oxygen in the atmosphere absorbing UV radiation.

But the claim is false. Experts described it as “creative fiction” and said the theory crumbles when assessed scientifically.

The post (archived here) shared to the “Climate change reality forum” Facebook group reads: “The Greenhouse Effect is a hoax. It does not take into account 99.96 per cent of the volume of the atmosphere. Nor does it take into account the kinetic movement of all the molecules of the atmosphere, which allows to measure their temperature.”

A screenshot of the Facebook post
 The Facebook post claims the “Greenhouse Effect is a hoax”. 

The post then links to a study by “independent researcher” Rogelio Perez Casadiego.

He challenges the recognised and scientifically-backed greenhouse effect theory and asserts that oxygen in the atmosphere absorbs UV radiation and causes global warming.

The greenhouse effect is a process where the sun’s heat is trapped by greenhouse gases that act like a blanket around the earth. Leading scientific bodies are in agreement that as greenhouse gases have increased due to human activity, the blanket around the earth is effectively thicker, warming the planet (see here, here, here and here).

Mr Casadiego disagrees. His study concludes: “The heat and global warming of the planet are due to the absorption of ultra-violet radiation by oxygen from the atmosphere…Therefore, the greenhouse effect paradigm must be reconsidered, as the explanation of heat and global warming.”

Professor David Karoly, a geography and atmospheric sciences expert at the University of Melbourne, said the claim was “creative fiction” and pointed out Mr Casadiego’s study has not been peer-reviewed and said it did not meet “sufficient criterion for scientific reliability”.

While he agreed UV radiation is absorbed by oxygen and the ozone, he said the process does not contribute to global warming.

“Yes, UV radiation from the sun is absorbed in the upper atmosphere…which leads to the peak in atmospheric temperature in the atmosphere at the top of the stratosphere and in the lower mesosphere, at the stratopause, at heights around 50km,” he told AAP FactCheck via email.

“This prevents almost all of the harmful UV radiation reaching the lower atmosphere and the surface.

“There is almost no absorption of UV radiation at the surface and it does not contribute to global warming.”

He added that there is no long-term trend in solar UV radiation at the top of the atmosphere, as measured by satellites, or longer-term as measured at the surface. 

“So it cannot be contributing to the global warming trend of 1.1C over the last 120 years,” he said.

Dr Benjamin Pope, an expert in astronomy and physics at the University of Queensland, described the claim as “bogus”.

A solar flare erupting on the sun's northeastern hemisphere
 There’s no long-term trend in solar UV radiation at the top of the atmosphere measured by satellites 

“If UV absorption by oxygen were causing global warming, why now? The proportion of oxygen in our atmosphere is not significantly changing; the proportion of CO2 is,” he told AAP FactCheck by email. 

“And why would this matter anyway; the absorption of incoming light isn’t the issue (whatever the atmospheric composition, it all has to be absorbed or reflected); the absorption of outgoingÔÇï light is the issue.”

He added: “The paper doesn’t even do any calculations, and it doesn’t address what the greenhouse effect is.”

Professor Peter Rayner, an expert in physics and atmospheric sciences at the University of Melbourne, said the post “is wrong both in its physical explanation of how absorbing radiation warms the atmosphere and its assumption of what is treated in the models atmospheric scientists use”.

He said: “If UV radiation was responsible for warming, it would happen less at night (it actually happens more) it would happen less in winter (it doesn’t).

“Finally, we can measure the changes in infrared trapping of radiation using satellites orbiting the earth. These show trends which fit very well with the greenhouse theory.”

The greenhouse effect is well established with significant and extensive evidence to support the theory, see examples here, here, here and here.

The Verdict

The claim that global warming is caused by oxygen absorbing UV radiation, not the greenhouse effect, is false.

Multiple experts told AAP FactCheck the claim crumbles when assessed scientifically. In particular, there has been no significant increase in the proportion of oxygen in the atmosphere to explain the planet’s warming. 

The scientific world is in agreement about the role of the greenhouse effect with copious sources of evidence to support the theory.

False ÔÇô The claim is inaccurate.

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