Posted on 11 July 2023 by John Mason, BaerbelW

On February 14, 2023 we announced our Rebuttal Update Project. This included an ask for feedback about the added "At a glance" section in the updated basic rebuttal versions. This weekly blog post series highlights this new section of one of the updated basic rebuttal versions and serves as a "bump" for our ask. This week features "The human fingerprint in global warming". More will follow in the upcoming weeks. Please follow the Further Reading link at the bottom to read the full rebuttal and to join the discussion in the comment thread there.

At a glance

Since the pre-industrial era, we have burned ever-increasing amounts of fossil fuels. This we can see for ourselves, often just by looking out of the window or hear, by listening to the flow of traffic. The sights and sounds of fossil fuel burning, constant, perpetual.

We cannot see or taste carbon dioxide, one of the two main products of that combustion, the other being water vapour. But it's constantly heading up into our atmosphere – in 2021 alone the figure for such emissions, according to the International Energy Agency, was 36,300,000,000 tonnes of the stuff. Just imagine for a moment that amount of sand piled up in a heap!

Once up there, one key difference between carbon dioxide and water vapour becomes critically important. Water vapour condenses to form clouds and freezes to form ice crystals. Rain, hail, sleet and snow all fall from clouds – it's a constant, ongoing cyclic process, even though different places see much more – or much less precipitation.

Carbon dioxide has no liquid state at the pressures encountered in Earth's atmosphere. Instead, at normal atmospheric pressures, it sublimes from solid to gas at −78 °C. Solid carbon dioxide is also known as dry ice, but cannot form in the range of temperatures found within Earth's atmosphere, although it is produced industrially for various purposes. So as opposed to water vapour, carbon dioxide is an example of a non-condensing gas: once up there it stays up there for a long time. That's why our vast CO2 emissions are causing levels of the gas to build and build.

If you needed a smoking gun in order to accept the above, there is one: carbon dioxide derived from fossil fuel burning has a very distinct chemical fingerprint that is readily measurable in air samples. To find out how we do that, read the further details below. Such measurements, with a trend precisely following the pathway we would expect due to our increasing emissions, show that far from being someone else's problem, one way or another we are all bang to rights in this case.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above

Click for Further details

In case you'd like to explore more of our recently updated rebuttals, here are the links to all of them: