Sunny outlook on the causes of global warming belies the scientific evidence

A Facebook post claims that carbon dioxide emissions do not cause global warming, blaming climate change on the sun rather than human activity.

However, scientists say that human actions, such as burning fossil fuels, deforestation and land clearing, are leading to increased concentrations of greenhouse gases in the air.

The Publishshared on the Australian climate skeptics page, makes many claims about global warming, including: “There is no ‘man-made’ global warming. It is literally impossible for Earth to become a conventional greenhouse because of man-made carbon dioxide emissions.

He adds: “Furthermore, the propaganda of ‘man-made global warming’ has made ‘warming’ a bad thing when in fact global warming is still good for the Earth… The Sun is the cause of all ‘climate change’.”

The Facebook post says climate change is good for the planet and the sun is the main cause.

The allegation is false. The experts said AAP Fact Check increasing concentrations of greenhouse gases from human activity are causing climate change.

Professor Brendan Mackey, a climatologist from Griffith University, said that the increase in “atmospheric concentration due to human activity is an established scientific fact”.

‘This impact is attributable to the so-called ‘Greenhouse effect‘where increases in the concentration of specific gases and vapors in the atmosphere, including relatively small changes in CO2 concentrations, cause global warming and subsequent changes in the Earth’s climate system,’ he said. he said in an email.

Professor Mackey pointed out the Intergovernmental Panel on Climate Change (IPCC)which regularly assesses all aspects of climate change “including how the Earth’s climate is changing, including under the influence of human activities, in particular the greenhouse gases released into the atmosphere by burning fuels fossil fuels for energy and deforestation and forest degradation”.

“This latest assessment concluded that it is now unequivocally that human influence has warmed the atmosphere, ocean and land, and that widespread and rapid changes in the atmosphere,” he said .

The last Summary of the IPCC Assessment Report for Policymakers under Current Climate A.1.1 states: “The observed increases in concentrations of well-mixed greenhouse gases (GHGs) since about 1750 are unequivocally caused by human activities. Since 2011…concentrations have continued to rise in the atmosphere, reaching annual averages of 410 parts per million (ppm) for carbon dioxide” (page 4).

NASA says evidence because “rapid climate change is compelling”, including rising average global surface temperature, warming oceans, shrinking Greenland and Antarctic ice caps, rising sea levels the sea and an increase in extreme weather events.

The The European Commission says “the burning of fossil fuels, the felling of forests and the raising of cattle are increasingly influencing the earth’s climate and temperature”, adding a huge amount of greenhouse gases “to those naturally present in the world. atmosphere, increasing the greenhouse effect and global warming”.

The Royal Society of the United Kingdom also said human activity has caused global warming. Its website states that scientists “have determined that, when all human and natural factors are taken into account, the Earth’s climate balance has been shifted in favor of warming, with the major contributor being increased CO2.”

Cut trees in the forest of Mountain Ash, Victoria
Humans who cut down forests and clear land release more carbon dioxide into the atmosphere.

Professor Janette Lindesay, an expert in climatology from the Australian National University, said AAP Fact Check the post’s claim is false, explaining that there is a direct link between human-made carbon dioxide emissions and rising air temperatures.

“Carbon dioxide is a natural gas composed of carbon and oxygen. Along with other atmospheric gases known collectively as “greenhouse gases”, carbon dioxide absorbs long wave radiation (thermal energy) that would otherwise travel through Earth’s atmosphere into space and leave the planet noticeably colder,” she said in an email.

“Increasing the concentration of greenhouse gases, including carbon dioxide, increases the heat-trapping function of the atmosphere (the enhanced greenhouse effect) and increases temperature.”

Prof Lindesay said each molecule of carbon dioxide ‘lasts between 300 and 1000 years once it is in the atmosphere’, meaning the steady increase in emissions builds up over the years.

“The natural, pre-industrial concentration of atmospheric carbon dioxide has varied between 180 and 280 parts per million for at least the past 800,000 years,” she said.

“The most recent data shows that in May 2022, the concentration of carbon dioxide, which continues to increase year on year, was 418 ppm (global average on the surface of the Earth above the This rapid increase is due to human activities, particularly industrial and energy.

Professor Lindesay said emissions from fossil fuels had exceeded emissions from natural sources and were proven due to the chemical difference between atmospheric carbon dioxide of natural and fossil origin.

“Fossil fuel emissions, in particular, are effectively one-way; fossil fuel deposits form slowly, over millions of years of geologic time,” she said.

“The result is that continued emissions of fossil fuels – which are unmistakably man-made – continue to build up in the atmosphere. This increases atmospheric trapping of heat, upsetting the balance between incoming solar energy and energy leaving the Earth’s surface and atmosphere; the result is higher temperatures.

Similar claims about global warming have been denied by AAP Fact Check here and other outlets here, here and here.

The verdict

The claim that man-made carbon dioxide emissions do not cause global warming is false. Climate experts said AAP Fact Check greenhouse gas emissions from human activity, such as burning fossil fuels and deforestation, have exceeded emissions from natural sources. They say emissions of carbon dioxide and other greenhouse gases from human activity accumulate over time, impacting the climate.

Fake – This statement is incorrect.

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Teresa H. Sadler