Arguments
Fact brief - Can CO2 be ignored because it’s just a trace gas?
Posted on 18 January 2025 by Guest Author
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Can CO2 be ignored because it’s just a trace gas?
While carbon dioxide is a small part of the atmosphere, it has a large impact on climate as a greenhouse gas.
Nitrogen and oxygen make up around 99% of the atmosphere, but neither traps heat. Less than 0.05% of the atmosphere is made up of greenhouse gases, which do.
Without greenhouse gases, the Earth would be too cold to support most life, with average temperatures 2° F below zero (-18° C).
On the other hand, increasing greenhouse gas concentrations elevates temperatures. Human activities such as fossil fuel burning have raised CO2 concentrations from 280 parts per million in pre-industrial times to 424 parts per million in 2024. Over the same period, the planet has warmed 2° F (1.3° C) on average.
Climate scientists agree that emissions of CO2 and other greenhouse gases are responsible for this observed rise in temperature despite their relatively low concentration in the atmosphere.
Go to full rebuttal on Skeptical Science or to the fact brief on Gigafact
This fact brief is responsive to conversations such as this one.
Sources
NASA Carbon Dioxide
MIT Climate Portal How do greenhouse gases trap heat in the atmosphere?
Columbia Climate School You Asked: If CO2 Is Only 0.04% of the Atmosphere, How Does it Drive Global Warming?
NASA Steamy Relationships: How Atmospheric Water Vapor Amplifies Earth’s Greenhouse Effect
EIA Energy and the environment explained
Carbon Brief State of the climate: 2024 sets a new record as the first year above 1.5C
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Carbon dioxide is a trace gas, but to put that in perspective, the amount of CO2 in the atmosphere is not physically insubstantial.
Focusing on parts per million to the exclusion of actual amounts is employing a mathematical sleight of hand. A sleight of hand that suits those who don't accept the scientific orthodoxy behind the 'warming' role of CO2.
Which is why "trace" amounts of CO2 supports the massive amount of plant life on land and in water.
Noel:
An illustration of why ppm is a bad set of units to look at the radiative effects of CO2 forms part of the discussion in this blog post I did a few years ago. (To toot my own horn.)
https://skepticalscience.com/from-email-bag-beer-lambert.html
Nicely stated Noel.
"Which is why "trace" amounts of CO2 supports the massive amount of plant life on land and in water."
Thanks for the reminder Bob of your very interesting and illustrative paper.
Yes, indeed, Evan (and Noel).
It is always interesting to see how the contrarians can both argue that "CO2 is a trace gas" and can't possibly imagine that it can have any effect - yet at the same time they argue that the CO2 effect is saturated, so adding more can't have any additional effect. And then turn around and do the "CO2 is plant food" dance.
If Elon Musk wanted to give me 0.04% of his net worth, I'm sure I could live a long and wealthy life on "trace money".
Noel Yrrep,
In addition to your well presented questioning of the questionable claims made-up by people who are resistant to learning how CO2 levels in the atmosphere significantly affect the global average surface temperature, the ‘hard of learning’ would struggle to explain:
How the surface is so much warmer than it would be without ‘trace amounts of ghg’ in the atmosphere. What evidence-based, independently verifiable, alternative understanding do they offer?
Some might claim that God made it this way, in a way that humans cannot ruin, therefore, it is not necessary for people to understand how it works. Others may claim that the activity in free market capitalism (the developed economy) will naturally be the best way to identify and solve any developed or developing problems if it is free from external observation and influences. Still Others may claim that popularity of a belief justifies it. And some may claim that everyone's personal opinion is as valid as any other opinion.
Those would be arguments based on orthodoxy (which means ‘the right opinion’).
Science is not a matter of opinion. Science, done scientifically, develops evidence-based improved understandings of what is going on.
So I would recommend that instead of “...those who don't accept the scientific orthodoxy behind the 'warming' role of CO2.”, you should say something like “...those who resist improving their awareness and understanding of the scientifically developed knowledge regarding the 'warming' role of CO2.”