Common misunderstandings about atmospheric carbon dioxide

I keep coming across common misunderstandings about the problems caused by atmospheric carbon dioxide. Here are the answers to some of them.

Why increasing atmospheric CO2 is a problem

The sun’s radiation powers life on earth. Without it, earth would be a sterile, dead planet.

Greenhouse gases in the atmosphere, the most important being carbon dioxide (CO2), trap some of the sun’s heat and prevent it being reflected back into space. This keeps the planet warm – 33 degrees warmer than it would be without them – and habitable.

The increased use of fossil fuels (oil, gas and coal) is increasing atmospheric carbon dioxide so that it is now 30% higher than it used to be. This is trapping more heat and raising the earth’s temperature.

This in turn puts more energy into the climate systems and makes them more unstable. The result is a trend towards more extremes of weather – flood and drought, storms, ice melt, etc. All this will make life difficult for most of the earth’s inhabitants (animals and people) and unbearable for some.

If we don’t reduce fossil fuel use fast, the human race faces significant problems. Read more in The science of global warming.

Wrong things being repeated

Here are some of the misunderstandings I keep hearing:

1. Carbon dioxide is a plant food. Greater concentrations will only help plants grow, so won’t cause any harm.
2. CO2 is only 0.04% of the earth’s atmosphere. How can such a low concentration have any affect?
3. 95% of the CO2 is natural, caused by volcanoes, plant respiration and decomposition. Changing the human-caused CO2 will have little effect.
4. CO2 was high in the geological past and the earth survived. Why should it be a problem now?

Gaining understanding

Here are the scientific facts (as best as I can present them) about these questions.

Carbon dioxide is a plant food.

This is totally irrelevant. The processes outlined above have nothing to do with plant nutrition. They have to do with the ability of CO2 to absorb heat energy and so prevent it radiating into space. The physics of this process is well known.

Anyone who presents this argument has either been misled by someone they shouldn’t have trusted, or they are actively presenting misinformation.

CO2 is only 0.04% of the earth’s atmosphere.

This is true, but misses the point. Some substances can have harmful effects at very low concentration, while others don’t. Atmospheric CO2 isn’t poisoning anyone, it just happens to absorb heat energy. The physics of this has been known for 150 years.

95% of the CO2 is natural. Changing the human-caused CO2 will have little effect.

This is simply false. Before the industrial revolution, most of the atmospheric CO2 was natural, with some caused by people burning firewood. But the 30% increase since the industrial revolution has been almost totally caused by the burning of fossil fuels and deforestation.

Volcanoes have little impact on CO2 – they tend to lower temperatures if anything because they put ash into the atmosphere, preventing radiation reaching the ground.

So the natural sources of CO2 remain much the same, and it is the human sources that have caused the increase in atmospheric CO2 that is raising temperatures.

Read more at The causes of global warming.

CO2 was high in the geological past and the earth survived.

This is also true, but irrelevant. Atmospheric CO2 has been up to 10 times higher at some times in the past, and the earth’s ecology and climate adapted to this.

But there weren’t 8 billion people around then!

If we allow the CO2 and temperature to increase now, the earth’s climate and ecology will adapt again, and cause enormous impacts on human beings and animals. The world’s infrastructure, food systems, livelihoods and life expectancy will all be severely affected. Life as we know it now will be totally changed.

Even if we limit the temperature rise to 2°C, there will be huge changes to most people’s lives, especially in some poorer countries.

Where do they get these ideas?

I’ve seen the same statements made many times, so it seems there must be a common source of misinformation.

Studies have shown that fossil fuel interests have tried (often successfully) to spread misinformation to weaken the resolve to address climate change. The same tactics were used to delay action on the connection between smoking and lung cancer, leading to many more deaths. In some cases, the same organisations have been involved.

They will doubtless keep trying. The objections to climate action have changed over the years. As one misleading argument is shown to be wrong, it is replaced with another.

The Who almost said it long ago: “Don’t be fooled again!”

Photo: Pixabay via Pexels.