Recently an argument has been going around the sceptic community that CO2 does not trap heat because there is too little of it in the atmosphere. CO2 comprises only 400 parts per million of the atmosphere, that is only 0.04%. Only about 4 atoms in every 10,000 are absorbing heat so their effect must surely be negligible.
This argument is quite wrong because it ignores the radiation cross-section of CO2 which is huge in the infrared range, as it is for other tri-atomic molecules such as ozone (O3) and water vapour (H2O). Think of three balls (the atoms) connected by two springs (the chemical bonds). There are a large number of ways that these springy, bouncy things can vibrate and their frequencies of vibration are in the infrared range of wavelengths. They act like antennas sucking in radiation as it goes past and converting it to mechanical vibration (i.e. heat). By comparison the di-atomic molecules of N2 and O2 which make up the bulk of the atmosphere don’t vibrate in the infra-red because there are no vibrational modes to take up the energy. For infrared radiation the tri-atomic molecules look like soccer balls in a background of sand grains: not many of them absorb a lot of radiation.
The issue with CO2 is the opposite: there is so much CO2 in the atmosphere that the absorption band is already saturated; adding more CO2 makes very little difference. The climate modelers get around this problem of making CO2 the bogeyman with a gigantic fudge. It is called “water vapour positive feedback” whereby extra H2O is arbitrarily added to the model to do the heavy lifting when it comes to changes in radiation absorption.
Here are some valid arguments in refutation of the Climate Change meme:
- Met balloons measure the temperature gradient of the atmosphere all over the world many times a day. The observed temperature gradients fit a thermodynamic model. They do not fit a radiation transport model.
- The bomb test curve shows that CO2 in the atmosphere is in approximate equilibrium with the ocean. 98 percent of CO2 is in the deep ocean. It comes out of the ocean in regions of upwelling currents and is absorbed back again by diffusion. Of recent increases more than 80 percent are due to this upwelling and human activity less than 20 percent. Since the beginning of the Industrial Revolution we have only contributed one percent of the total CO2 in the ocean-atmosphere system.
- Variations in upwelling currents cause variations in both atmospheric CO2 and global temperature over time. Some of these variations are most likely caused by changes in volcanic activity on the ocean floor. More than 80 percent of the world’s volcanoes lie beneath the ocean. These effects are unacknowledged by climate scientists and ignored in their models.
- Climate models have no predictive power. They don’t work.