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.”
One of the fundamental problems for understanding how a "trace" gas can have such a large impact is that most people don't understand how delicately balanced our ecosystem is. Consider that the orbits of Jupiter and Saturn, over 100,000-yr cycles (i.e., Milankovitch cycles), cause sealevel to go up and down 400 ft! That is a delicately-balanced system!
Evan @6,
Your make a good point about the sensitivity of our amazing planet’s global climate conditions. It has prompted the following thoughts regarding attempts to ignore or dismiss CO2 impacts ...
The warming impact of increased levels of CO2 have been understood for more than 125 years. And the natural causes of glaciation and inter-glacial periods, like the Milankovitch cycles, have been reasonably understood for more than 80 years.
A challenging understanding, an inconvenient truth, is that human CO2 impacts causing global warming may be helpful in the future but are not helpful now. Those distant future actions could make the next natural glaciation event more ‘livable’.
The next glaciation is expected to naturally happen about 50,000 years from now. But studies, like the one reported in the Carbon Brief in 2016: Human emissions will delay next ice age by 50,000 years, indicate that the human caused increased CO2 levels have likely delayed the next glaciation by 50,000 years. That is nothing to be proud of. It was Too Much Too Soon.
It would be ‘great’ if lots of easy to access fossil fuels were still available for future humans to use to limit the negative impacts of future glaciations.
Fossil fuels are undeniably non-renewable. Future generations cannot benefit from burning them as much as current generations do. Rapidly ending fossil fuel use would leave more ‘limited resources’ for the benefit of future generations and reduce the climate change harm done to people today and to future generations. However, the ‘competitive marketplace’ fails to ‘naturally’ develop towards those understandably ‘great’ objectives. In fact, there is ample evidence that the marketplace developed, and continues to develop, misinformation efforts against the development of such ’helpful external influences on the marketplace’.
The undeniable marketplace efforts against learning to be less harmful and more helpful to Others clarifies what competitive free market activity can be expected to accomplish. The fundamental market function is managing the distribution and benefits from the use of scarce resources. It develops replacement alternatives as resources become scarcer. However, the marketplace will only seriously develop replacements that are less expensive than the increased cost of the activities that rely on scarcer resources (note political efforts to reduce the costs of fossil fuels).
More importantly, the market is unlikely to care to reduce harm or ensure that harm done is repaired. Limiting harm done, and avoiding the challenge of getting the beneficiaries of harm done to repair the damage done, requires external influence to make the more harmful ways less popular, more difficult, and more expensive.
Hopefully efforts to limit the success of misinformation, not just regarding climate science, will result in more helpful and less harmful political action. It is common sense that political actions need to be less likely to cycle in ways that are significantly negative for the future of humanity. However, limiting the sensitivity of political actions to harmful misunderstandings is likely less certain than improving the understanding of the sensitivity of the climate on this amazing planet to the impacts of human activity.
Scientific understanding is certain to be constantly improving the ability to develop sustainable improvements and limit harm done - The politics of popularity of beliefs is not certain to develop sustainable improvements or limit harm done.