Sometimes someone brings up an argument in the comment section that’s interesting enough to deserve dissection. Not every argument people bring up against climate change is idiotic, some errors are understandable.
Here is an example:
Flat wrong. Total lie. Plant life thrives up to and beyond 12000ppm, higher than any known previous atmospheric levels. We know this because commercial greenhouses go to the cost of installation and management of risks for systems that boost it this high, to make their crops grow better.
I have some basic sympathy for this error. I wrote that our plant life is adapted to the level of CO2 it experienced during the Holocene. So how is it possible then, that we raise CO2 levels in greenhouses, to benefit from higher yields? Doesn’t that contradict the whole idea of agriculture suffering when CO2 concentrations increase? Can’t we just turn the whole planet into a giant greenhouse and watch our agricultural yields explode?
Well, to understand the error, you have to understand that in a greenhouse, human beings control basically every aspect of the environment. It’s basically the most capital intensive method of food production that we have. This allows plants to grow very rapidly, under conditions of high carbon dioxide. We create the perfect environment to use higher carbon dioxide concentrations to our own advantage. Consider some of the ways in which we intervene for our plants in a greenhouse:
-You regulate the temperatures, to avoid any extremes the plants can’t deal with.
-You protect the plants from harmful UV radiation, with the glass.
-You keep out any nasty insects that might want to eat your plants, through the physical barrier and by spraying pesticides.
-You keep out the weeds that might compete with your plants, through the physical barrier and by spraying pesticides.
You spray a bunch of fungicides so that no fungi threaten the plants in your greenhouse.
-You give the plant every nutrient when it needs, it has constant access to water, nitrogen and anything else it might need.
And so although the plant became more vulnerable, because it is focused on utilizing carbon dioxide to the detriment of everything else, it doesn’t suffer under the vulnerability, as we create the conditions in which it’s not confronted with the kind of threats it’s vulnerable to.
Take a look at how a plant becomes more vulnerable when exposed to higher CO2 concentrations and how you don’t see these circumstances in greenhouse plants.
-Temperature extremes. Plants become more vulnerable to freezing damage under higher CO2 concentrations. The same temperature causes more frost damage under high CO2 conditions as it does under low CO2 conditions. But in your greenhouse, they don’t experience such conditions of course, you make sure they don’t experience any cold.
-UV radiation. Some plants become more vulnerable to UV B radiation induced damage when you raise CO2 concentrations. You don’t notice this in the greenhouse, because it’s blocked by the glass.
-Pest predation. You generally don’t let pests into your greenhouse. That’s a good thing, because with more CO2, your plants generally produce more of the compounds insects like to eat and generally less of the nitrogen based compounds they use to produce alkaloids toxic to insects. Hence we see that insect predation increases. This is seen for tomatoes too, but it’s not a concern in your greenhouse, because you spray pesticides there.
-What about weeds? Well, this one is easy. You can just look at which plants evolved under low CO2 concentrations and which ones under higher CO2 concentrations. Almost all the plants that we use as staple crops are grasses that evolved to specialize in surviving under low CO2 concentrations. Some like Maize show the rare C4 carbon fixation mechanism, that allows them to capture CO2 even when atmospheric concentrations are very low. The advantages they have over weeds disappear as the CO2 concentration in the atmosphere increases.
-Fungal predation. I personally think this is the biggest problem you will run into. Stem rust, one of the main pathogens for our wheat, becomes more damaging under higher CO2 concentrations.
-Nutrient availability. In your greenhouse, you tweak the nutrient mixture of your plants to make sure they get whatever they need to grow as fast as possible. But in the real world they run into nutrient limitations as you boost CO2 levels. Low phosphorus availability halves the effect of elevated CO2 on plant growth.
So I think I made my point clear: Elevated CO2 is generally great to boost plant growth in greenhouses, where you can tweak every other variable too, to make sure the plant can use the elevated CO2. It’s not so great in the real world, where your plants have to deal with climatic extremes, competition with insects, competition with other plants and competition for nutrients.
It’s kind of similar to how you could feed a chicken in a farm to become as fat as possible to boost your food production, if you don’t have to worry about the ability of the chickens and the rooster to defend themselves from birds of prey.
When you look at the 20th century, it’s clear that food production has so far benefited a lot from increased carbon dioxide concentrations. This doesn’t necessarily mean it will benefit from further increases in the future however. In addition, the benefits we’ve enjoyed from higher CO2 concentrations so far depend on the other successes we’ve had:
-We control the nutrient input, whatever the plants need is what they get from us.
-We spray a cocktail of pesticides, to make sure no weeds, fungi or insects can mess with our plants.
-We rapidly breed whatever disease-resistant variety we can find and spread it around the world.
-We spray fungicides for all the fungal pathogens.
In other words, whatever damage we have already done to our ability to engage in pre-industrial methods of agriculture, is currently being obscured by the industrial technology we’re using to boost food production!
Greenhouse production of food works great with higher CO2 concentrations, but it’s not very sustainable. Some of the Dutch greenhouses right now are sitting empty, they’re not growing tomatoes because the cost of energy is simply too high. Next year we will start to see the same problem for fertilizer, as the factories that produce it were shut down. Eventually we won’t be able to produce herbicides, pesticides and fungicides anymore either.
And then once you have to produce your food the way a medieval peasant had to produce it, you discover: Nature is not cooperating!
You will find yourself asking questions like:
Why do I have so many insects? Answer: Your winters don’t get cold enough anymore, so they don’t die in droves during winter.
What the fuck is happening to my wheat? Answer: It’s called stemrust, it spreads like wildfire if you don’t have the right resistant breed and pesticides available.
Why is my maize overgrown by weeds? Answer: As an efficient carbon utilizing C4 plant, Maize doesn’t benefit as much from higher CO2 concentrations as the weeds that surround it do.
Agriculture emerged in the Holocene, because the conditions for it were right. Now that the conditions are no longer right for agriculture, it will gradually start to die out again.
Perhaps you should have listened to the autistic (ZOMG!) Swedish girl after all.