The CO2 problem in six easy steps (2022 Update)
10 JUL 2022 BY GAVIN 43 COMMENTS
One of our most-read old posts is the step-by-step explanation for why increasing CO2 is a significant problem (The CO2 problem in 6 easy steps). However, that was written in 2007 – 15 years ago! While the basic steps and concepts have not changed, there’s 15 years of more data, updates in some of the details and concepts, and (it turns out) better graphics to accompany the text. And so, here is a mildly updated and referenced version that should be a little more useful.
Step 1: There is a natural greenhouse effect.
The Earth’s Energy Budget (NASA)
The fact that there is a natural greenhouse effect (that the atmosphere restricts the passage of infra-red (IR) radiation from the Earth’s surface to space) is easily deducible from; i) the mean temperature of the surface (around 15ºC) and, ii) knowing that the planet is normally close to radiative equilibrium. This means that there is an upward surface flux of IR around \sigma T^4 (~398 W/m2), while the outward flux at the top of the atmosphere (TOA) is roughly equivalent to the net solar radiation absorbed (~240 W/m2). Thus there must be a large amount of IR absorbed by the atmosphere (around 158 W/m2) – a number that would be zero in the absence of any greenhouse substances. Note that this IR radiation is sometimes called longwave (LW) radiation to distinguish it from the shortwave (SW) radiation coming from the sun.
Step 2: Trace gases contribute to the natural greenhouse effect.
https://www.realclimate.org/index.php/archives/2022/07/the-cos2-problem-in-six-easy-steps-2022-update/
