TheCable

A Facebook post has claimed that the greenhouse effect is a hoax.

“The greenhouse effect is a hoax. It does not take into account 99.96% of the volume of the atmosphere. Nor does it take into account the kinetic movement of all the molecules of the atmosphere,” reads the social media post. 

The post, which was shared on a climate change reality forum, further claimed that “‘global warming is actually caused by oxygen in the atmosphere absorbing UV radiation”.

WHAT IS THE GREENHOUSE EFFECT?

The greenhouse effect is a process through which gases in the atmosphere trap heat from the sun. The gases involved in the heat-trapping process are referred to as greenhouse gases, they include carbon dioxide, methane, nitrous oxides, and water vapour.  

National Aeronautics and Space Administration (NASA), the United States agency in charge of space science and technology, likened greenhouse gases to a “blanket wrapped around the earth, keeping the planet toastier than it would be without them”. 

It is with the help of the greenhouse effect that the earth is comfortably warmer, keeping the planet at an average of 15 °C, which makes the earth inhabitable for humans. 

Scientists have established that greenhouse gases have increased tremendously in the last century due to human activities, essentially burning fossil fuel, which adds carbon dioxide (Co2) to the air. 

Consequently, increased carbon dioxide in the atmosphere implies that more heat is trapped, resulting in a rise in global temperature. 

IS GLOBAL WARMING CAUSED BY OXYGEN IN THE ATMOSPHERE ABSORBING UV RADIATION?

The claim that the warming of the planet is due to the absorption of ultraviolet radiation by oxygen from the atmosphere is unverified and has no scientific basis. 

In a scientific report titled the primary cause of warming, it was established that the atmosphere truly absorbs and filters the highest energy components of solar radiation, through the photoionization of gasses, such as nitrogen and oxygen. However, there is no scientific evidence that the process contributes to global warming. 

In 2022, David Karoly, a professor of geography and atmospheric science at the University of Melbourne, was quoted to have said: “Yes, ultra-violet 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, in the lower mesosphere, and at the stratopause, at heights around 50km.”

The geography expert added that the absorption of ultra-violet radiation from the sun in the upper atmosphere “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 said. 

VERDICT

The claim that the greenhouse effect is a hoax is false. 

Credible scientific agencies like NASA have established the relationship between the greenhouse phenomenon and global warming. 

Also, the claim that global warming is caused by atmospheric oxygen absorbing UV radiation is false. There is no scientific evidence to back such a bogus claim. 

Furthermore, experts say if ultraviolet absorption by oxygen was responsible for global warming, in the last century, the proportion of oxygen in the atmosphere would have changed significantly, compared to the proportion of CO2 – which explains increased warming. 

This fact check was produced by TheCable with support from Code for Africa’s PesaCheck, International Fact-Checking Network, and African Fact Checking Alliance network.