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.

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.

Let me be more clear. The tone of the article and the menacing on the Title made me uncomfortable. I don't understand why we have to resort to fear instead of reason on important issues.

It's an invasive species. It's called "famine weed" because it can cause a disastrous collapse in crops.

https://en.wikipedia.org/wiki/Parthenium_hysterophorus

> It infests pastures and farmland, causing often disastrous loss of yield, as reflected in common names such as famine weed.

It aggressively colonises disturbed ground. It is one of the hundred most invasive species in the world. It causes huge losses in crop production.

https://www.cabi.org/isc/datasheet/45573

> arthenium hysterophorus is an annual herb that aggressively colonizes disturbed sites. It is considered as one of the ‘100 most invasive species in the world’ by the IUCN

> In India, the yield losses are reported as up to 40% in several crops and a 90% reduction of forage production (Gnanavel, 2013). Parthenium hysterophorus is now being reported from India as a serious problem in cotton, groundnuts, potatoes and sorghum, as well as in more traditional crops such as okra (Abelmoschus esculentus), brinjal (Solanum melongena), chickpea and sesame (Kohli and Rani, 1994), and is also proving to be problematic in a range of orchard crops, including vineyards, olives, cashew, coconut, guava, mango and papaya (Tripathi et al., 1991; Mahadevappa, 1997; Gnanavel, 2013).

They are not fear mongering. This is a calm, evidence based, bit of research about a very worrying species.