David Karoly is an academic with a meteorological background. He is also one of Australia’s leading climate alarmists. He recently had a Q&A in the media, presenting key points which he asserted proved humans were causing climate change. Every point he made was wrong, plainly and evidently wrong. This is without even considering that the current climate and the slight changes in temperature and increases in atmospheric CO2 have proved to be beneficial to the world with increased plant growth and agricultural output at record levels. Such considerations of course would disrupt the gloom and doom narrative of the alarmists.
The first point Karoly asserts is that CO2 is at record levels. The current level is about 415ppm. Karoly says this is the highest CO2 has been for 3 million years. This is wrong. Past CO2 levels are measured from ice cores in Greenland and the Antarctic. The further you drill down and retrieve ice the further back in time you go. The ice core records show a remarkably even record of past CO2 with the range being between 172 and 300 ppm as the famous Luthi et al paper shows.
This is wrong. The ice core record has a major problem: preferential fractionation. The problem is that while it is true the ice cores have air including CO2 trapped in them, the weight and pressure of the ice above squeezes out these gases giving an unreliable record. This process of squeezing is called fractionation. The preferential comes into play because CO2 is squeezed out first. The result is the historical record of CO2 is too low and smooth. A technical discussion of this for those who are interested is here.
A more accurate record of past levels of CO2 is through plant stomata. Stomata are microscopic pores found in leaves and the stem epidermis of plants. They are used for gas exchange. The stomatal density in some C3 plants will vary inversely with the concentration of atmospheric CO2. A good discussion of the greater accuracy of stomata over ice cores is here. A visual depiction of the differences:
A longer period comparing stomata to ice core records:
There is a further aspect to Karoly’s wrong information: past temperatures. We are currently in an interglacial with warmer temperatures. There have been interglacials before:
The second point Karoly makes is a key one. Karoly says the increase in CO2 levels today are due to human emissions. This is the crucial central point of alarmism. If CO2 levels were natural it would not matter if CO2 did cause temperature to rise – it doesn’t, at least to anywhere the extent alarmists claim – because nature was doing it. In fact the CO2 rise is natural. The starting point for this is the IPCC report, AR4, Figure 7.3:
Some of these arguments were clever but ultimately hollow. Karoly appears to have invented a new one when he claims human emissions of CO2 are decreasing levels of oxygen in the atmosphere. This appears to be a variation of the old isotope argument and seems equally specious.
Fortunately, two papers were released by top-notch atmospheric scientists who refute, hopefully finally, the argument that CO2 levels are due to human activity. Hermann Harde and Ed Berry both wrote papers in 2019 which address all the claims by the alarmists and then refute them using basic physical laws and properties ( I should add that professor Bob Cormack developed a similar proof before both Hermann and Ed wrote their papers). Ed sums up the idea:
The simple model shows the ratio of human to natural equilibrium levels is equal to the ratio of their inflows. This means natural CO2 emissions cause 392 ppm of today’s CO2 level and human CO2 emissions cause only 18 ppm, for a total of 410 ppm today. If all human emissions were totally stopped and natural emissions remained constant, the level of CO2 in the atmosphere would fall by only 18 ppm in about 20 years.
This is not only consistent with physical laws and observations but also the IPCC’s own conclusions as shown in Figure 7.3. If humans only emit 3% of all CO2 emissions, humans can only be responsible for 3% of the increase in CO2 totals. So Karoly is wrong on point 2.
The third point Karoly uses is probably the simplest. The Diurnal Temperature Range (DTR) is the difference between the maximum and minimum temperatures over a 24 hour period. The maximum temperature occurs during the day, the minimum at night. Alarmism predicted that the rate of increase in the minimum temperature would be greater than the maximum temperature because global warming continued at night. If this were happening the DTR would be decreasing as nights warmed faster than days. So simple as that and Karoly thinks it is happening. Let's check the BOM:
3 strikes for Karoly. When is the alarmist scare going to end?