The facts that climate change deniers have to deny

The history of the Earth’s atmosphere over 4.5 billion years – once-huge levels of atmospheric carbon dioxide have been reduced by limestone formation and plant fossilisation, while we only now have oxygen because of the action of living systems we take far too much for granted. Graphic from

To deny that human beings are changing the climate of the Earth in very dangerous ways, you have to disagree with one or more of these facts:

  1. Carbon dioxide is a heat-retaining or greenhouse gas. This is easily demonstrated in a lab.
  2. The average temperature of Earth’s surface is determined in good part by the balance of greenhouse gases in the atmosphere, principally, carbon dioxide and water vapour (but also methane, nitrous oxide, ozone, and industrial gas pollution such as the HFC refrigerants in your car aircon.) Were it not for the natural balance of greenhouse gases, Earth’s average surface temperature would be 33C colder, or an average -17C, rather than the average 15C we enjoy.
  3. Fossil fuels are coal, gas and oil; they are quite literally fossilised plant material. This fossilisation process has, over hundreds of millions of years, removed carbon dioxide from the atmosphere and stored it underground as coal, gas and oil. Click here to understand how the composition of our atmosphere has changed over time.
  4. As plant matter has been fossilised in enormous quantities over millions of years, atmospheric carbon dioxide has been reduced from 4000 (!) parts per million half a billion years ago, to as little as 180 parts per million (during the Quaternary glaciation of the last two million years), and 280ppm by 1780.
  5. Burning fossil fuels – coal, gas and oil – produces large amounts of carbon dioxide (oxygen + carbon = carbon dioxide).
  6. The amount of carbon dioxide in the atmosphere has increased very sharply since pre-industrial times, from an average 280 parts per million before 1800 to over 400 parts per million in 2019.
  7. Adding a warming gas to the atmosphere is going to warm the planet. This has many immediate geophysical effects, which include:
  8. Increasing the evaporation of water, with average global water vapour levels having increased 5% over the 20th century, and,
  9. Increasing the retained heat of the oceans, which leads to sea level rise in good part due to the simple expansion of water when it warms.
  10. The World Coal Association argues that coal burning can continue at current levels for the next 150 years before running out. They are effectively arguing that we should use up, within a total time period of 400 years, a resource that has taken a million times longer, or 300 million years, to accumulate; effectively reversing the geological processes that have brought our atmosphere to a comfortable temperature and breathable composition.

If you’re a climate change denier, we’re curious to know which of these individual facts you disagree with?

As a sidenote, we would have no oxygen to breathe without living organisms, so taking care of the living plants, forests and phytoplankton that produce our oxygen seems prudent. As it happens, our burning of fossil fuels is currently reducing, very slightly, the amount of oxygen in the atmosphere. (Carbon dioxide = carbon + oxygen.)

And since it seems humanity will inevitably need alternative energy sources in 150 years when fossil fuels run out, even without climate change it seems it might be best to start investing in sustainable energy sources right now. Especially since mass burning of coal (due to volcanic activity) may have been the cause of the worst extinction event in Earth’s history.


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