"But it's just plant food!"

I touched on this particular point in my last post on the subject but I think it deserves its own post.  Global warming deniers often scoff at the notion of regulating carbon dioxide by pointing out that it's plant food.  If CO2 is plant food, how can it be bad?  Plants are good so feeding them must be good too, right?  So is it true?  Is CO2 plant food?

Yes, it is.  Carbon dioxide is plant food and plants do grow better with more of it, as anyone with a greenhouse could probably tell you.

Well OK, matter settled!  CO2 is plant food so more of it in the atmosphere will be good!

Well, no.  Actually, it would be very bad.  As with most overly simplistic statements, it doesn't quite measure up to the complexities of real life.  I'll get to the science in a bit but you really don't need a PhD to figure this out, all you need is a garden.  Having a garden will soon disabuse you of all overly simplistic notions about plants, I guarantee it!  For instance, a garden will teach you that:

a) Not all plants are the same!  There are plants you want - like pumpkins and daisies and roses and tomatoes - and plants you don't want - like poison ivy, weeds, thorns and burrs.

b) The plants you want require a lot of care and attention while the plants you don't want seem to thrive under any condition.

c) Lots of things can destroy your garden - too much heat, too much cold, not enough water, too much water, not enough fertilizer, too much fertilizer, pests, weeds... It's a fairly long list!

So, once you've learned these basic things while gardening, ask yourself again if you think more plant food would be good or bad.  Hint:  It won't just be the plants you want getting it.  See if YOU take steroids you become stronger than everyone else.  If EVERYONE takes steroids then all the people that used to kick your ass will still kick your ass but now they will have more muscles to do it with!

Global warming is terrible for plants.  The US Global Change Research Program, a high level cooperative research effort by combined agencies of the federal government, has several “Key Messages” about climate change effects on agriculture:

• Many crops show positive responses to elevated carbon dioxide and low levels of warming, but higher levels of warming often negatively affect growth and yields.

• Extreme events such as heavy downpours and droughts are likely to reduce crop yields because excesses or deficits of water have negative impacts on plant growth.

• Weeds, diseases, and insect pests benefit from warming, and weeds also benefit from a higher carbon dioxide concentration, increasing stress on crop plants and requiring more attention to pest and weed control. 

• Forage quality in pastures and rangelands generally declines with increasing carbon dioxide concentration because of the effects on plant nitrogen and protein content, reducing the land’s ability to supply adequate livestock feed.

• Increased heat, disease, and weather extremes are likely to reduce livestock productivity.   

So not only will the plants we like face stronger weeds, they will face more pests.  In warmer weather the pests will also live longer with no winter cold to kill them off.  Added to that will be the damaging effect of the extra heat drying up the plants and evaporating the water.  And when all that extra evaporated water comes down there will be too much of it which is once again very bad for the plants you like.


So in a nutshell, when it comes to more CO2 in the atmosphere the bad far outweighs the good.  Plants need a lot more than just more "plant food".  They need a nurturing environment.  If you don't believe me, go plant a garden.