Menacing ‘famine weed’ grows more toxic as carbon levels soar

My understanding is that, while plants thrive overall, higher CO2 in the atmosphere is expected to “dilute” the nutrients in farm crops because they will grow too fast[0]. These nutrients may already be impacted by industrial agriculture practices[1]. So it’s still not good news for humans.

[0] https://www.nationalgeographic.com/culture/article/140507-cr...

[1] https://news.utexas.edu/2004/12/01/study-suggests-nutrient-d...

The problem is that not all plants will win there, and probably not the plants we rely on: for the higher CO2 levels to be useful to a plant, it needs to be growth-bound by carbon acquisition.

Guess what no fertiliser I've ever heard of contains? Carbon. Carbon and oxygen are the two things agriculture has no need whatsoever for. If anything, higher carbon level might make agricultural products worse by making the plants grow faster at the cost of nutritional content.

I thought the implication of the article, though, based on their research, was that this plant did not use all of the extra CO2 to grow, but used some of it to produce more growth inhibitor which then cause crops to not grow. i.e. the experiment showed that the extra CO2 does not impact all plants in the same way, and does not necessarily impact plants in a way that is to the benefit of crops.

Citation needed.

I think reading the article always helps.

> The researchers grew two types of famine weed, one invasive and the other non-invasive, and exposed them to the atmospheric levels of carbon dioxide recorded in 1950 and 2020. In the invasive variety, parthenin concentrations peaked at the highest carbon levels

Only if you leave out the paragraph directly afterwards, where they tested it experimentally:

> The researchers grew two types of famine weed, one invasive and the other non-invasive, and exposed them to the atmospheric levels of carbon dioxide recorded in 1950 and 2020. In the invasive variety, parthenin concentrations peaked at the highest carbon levels. The results suggest that modern levels of carbon dioxide have contributed to the noxious weed’s toxicity.

I don't think I understand the point you are making about climate change deniers and conspiracy theorists. It seems to me that the article is consistent with the two points you made.

The implication of the article is that the extra CO2 in the atmosphere gives this plant an extra edge of other plants because the plants use it to produce more growth inhibiting chemicals rather than only growing more. As a result, in the presence of these plants, crops do not get the benefit of the extra CO2, because their growth is inhibited by the extra inhibitors more than the extra CO2 makes them grow.

It's not the case that more CO2 automatically means more plants. Plant growth has lots of components: water, light, nitrogen, etc. Adding more gas to a car's gas tank doesn't make it go faster, unless it's empty. Adding CO2 to the atmosphere doesn't make plants grow faster if that's not the limiting factor.

Instead, adding CO2 can cause it to metabolize differently. It will put growth into different components. In this case, it's a toxin that causes a lot of problems. That's news because people are going to have to deal with additional toxicity from this plant.

So this is novel information that people will need to respond to. That's not really conveyed by the journal article's title, "Recent CO2 levels promote increased production of the toxin parthenin in an invasive Parthenium hysterophorus biotype."

If that reads as feeding conspiracy theorists... honestly, what doesn't feed conspiracy theorists? In the lack of information they're free to simply make stuff up, or repeat things that have been debunked many times. There's just not a lot you can do about it, so I don't think it's worth taking them into account one way or the other.