“Now it’s more CO2 that will threaten crops“. But plants love CO2! Anthony Watts is confused by this UC Davis press release. Apparently “Rising CO2 levels threaten crops and food quality”. What’s confusing about this, Anthony:
…findings from previous research by Bloom and colleagues suggested that elevated levels of carbon dioxide decreased photorespiration and inhibited nitrate assimilation in plant shoots.
Oh, maybe that ‘whole CO2 is good thing’ isn’t going to stick, even though the partisans at CO2Science.org have an “amazing video”.
Wott's Up With That? 
This is a study that finds that, “Rising levels of atmospheric carbon dioxide interfere with plants ability to convert nitrate into protein…”
WUWT counters this with a CO2Science.org video. The cowpea plant is a ‘nitrogen fixer’, that gets its nitrogen from the air.
More generally, the skeptics aren’t able to see the elephant in the room. Increasing CO2 will raise the temperature, and change the climate, where the crops are grown.
For an overall view see Wikipedia’s ‘Climate change and agriculture’
http://en.wikipedia.org/wiki/climate_change_and_agriculture
Also see the Crock of the Week video: ‘Don’t it make my Green World Brown’
This isn’t particularly new. The Jasper Ridge Project run by Stanford came up with similar results as far back as 2002, but trying to get denialists to accept the reality is a ‘mare. It just doesn’t compute and they fight the very notion of too much CO2 being bad for the comparatively young grass species.
We seem to be bringing the ideal conditions of the Holocene to a more certain end as each decade goes by, and there are many out there who don’t mind cutting off their own noses and everybody else’s in spite of. I’m not sure if the coming age will be known as the Dunning-Kruger, the Dittohead, or the Agnotoligical Age; when stupid people ruled the Earth.