Last week we showed that the IPCC does, in fact, know that rising CO2 levels are leading to global greening. So the fact that they avoid mentioning it in their summaries can’t be blamed on ignorance. They discuss it in Working Group I Chapter 2, which is focused on observed changes to the climate system. But what about Chapter 3, which focuses on human-caused changes? Here, alas, they revert to habit and can’t think of anything helpful to say, except for a weirdly coded admission that it’s happening.
The code works by focusing the discussion on the “seasonal amplitude” of the annual CO2 level. Here’s what they say in the Chapter summary (p. 427):
“The main driver of the observed increase in the amplitude of the seasonal cycle of atmospheric CO2 is enhanced fertilization of plant growth by the increasing concentration of atmospheric CO2 (medium confidence). However, there is only low confidence that this CO2 fertilization has also been the main driver of observed greening because land management is the dominating factor in some regions.”
The “seasonal amplitude” refers to the fact that the average level of CO2 in the air worldwide cycles down during the Northern Hemisphere (NH) summer and up during the NH winter. And the reason it does so is that there’s more land in the NH than in the Southern Hemisphere (SH), and during the NH summer as plants grow they pull CO2 out of the air and build plant biomass.
Northern Hemisphere summer is Southern Hemisphere winter, of course. So during this part of the cycle SH plants are dying, releasing their stored CO2. But because there’s less land in the SH there’s less plant matter, and not enough release of stored CO2 to offset the amount being gobbled up in the greening NH. But come winter the reverse is true: NH plants die and release their CO2 stores and there aren’t enough plants in the SH to gobble it all up. Hence the seasonal swings in total levels of CO2 in the air every year.
So what has any of this background detail to do with global greening, or their verbal dancing around the topic? Simply that global greening is another way of saying there’s been an increase in the number and size of plants on Earth, and therefore the annual cycle of CO2 levels gets a bit larger each year. That’s what the IPCC is getting at, very obliquely, by referring to “the observed increase in the amplitude of the seasonal cycle of atmospheric CO2”. But it’s a deliberately obscure way of saying what in plain, honest English would be “there are more plants and the Earth has greened.”
Moreover, just in case someone does connect the dots and realize what they just squeezed out through gritted teeth, they throw in a claim that no one is quite sure if CO2 gets the credit because there are other factors that might be driving increased greening, such as land use changes. Despite the fact that if it’s the amplitude of the CO2 cycle that means CO2 is at the heart of the whole process.
As too often, they will make use of uncertainty wherever it helps them dismiss inconvenient truths. But the fact that there are other possible explanations for warming and much uncertainty about how important they are doesn’t cause them to express any doubts that CO2 is the only possible cause. Which really ought to cause an observed increase in the amplification of the suffusion of facial tissues with haemoglobin… if these people were the sort who blush when caught.
Yes. So true when it comes to the 'greening" of the planet. Some college kid asked me: "what do you mean by "greener earth"?" I said: you know, more plants."
I have not seen the latest IPCC. I'm hoping I can find it somewhere online.
I have been mentioning you (John) and your website (CDN) Alot lately. Even been referring people to the NOAA website too.
Some stop taking to me when they see that things coming out of NOAA don't actually fit their narrative. Some get mad, not sure if it's at me, you or their own constitutes after seeing like "The 97% Myth".
Wishing you all well. And keep up the good work.