During my discussions with a lot of climate change sceptics I’ve often heard that CO2 is plant food. And that putting more in the atmosphere is a good thing for plants, as they will grow faster and produce more food.
Which is a very good point. As you can see from the video from CO2Science, plants can indeed grow a lot faster if you give them more CO2. And this is exactly what a lot of growers do in their greenhouses. They add CO2 to stimulate the growth of their crops and increase their yields.
So what people are saying with this argument is that it’s just another fertilizer, like nitrogen. So you should get the same benefits if you increase a nutrient. But, with nitrogen we do see that there is a point where if you add to much nitrogen, the plants get more susceptible to pests. As they will grow so fast they cannot develop their defences properly or fast enough. And there’s even a point where to much nitrogen will kill plants.
So does this also happen with CO2 or do we just get the benefits from it?
Fortunately scientists are researching this very question. They did research on for example soybeans, grains and maize to see how plants respond to the increase in CO2 in the atmosphere. And most importantly, they did this in test fields outside of greenhouses. Where plants are subjected to the same environmental stresses as any other crop.
For example for soybeans they found that if they simulated the atmospheric content of CO2 predicted for 2050, that’s 550ppm, that the plants defences are weakened. Pests were able to eat more of the soybean plant, produce more offspring, and subsequently do more damage to the plant.
If you look at the research results for grains they found that if you subject them to the same CO2 levels this can reduce the protein contents of grains by up to 20%. As the higher CO2 levels reduced the plants ability to absorb nitrogen from the soil.
So increasing CO2 levels in a greenhouse does act as a fertilizer and gives yield advantages as those plants are protected from pests and the elements. But as soon as you expose plants to increased CO2 levels outside a greenhouse the results we see tell a different story. As current research indicates that positive effects are reduced, or offset, by environmental factors.
And these are just some of the effects of a plants direct exposure to an increase in CO2. I also haven’t included all the other effects an increase in CO2 will have on our ability to produce crops. As climate change will shift hardiness zones, change rainfall patterns and expose plants more and more to heat stress. There is a real chance we might loose the ability to produce crops in areas that are very productive at the moment. Like the american midwest.
These effect can have serious consequences for the amount of food we can produce. If we continue to increase atmospheric CO2 this will have as a consequence that we need to continually develop new technologies and crops to deal with it. And the question remains if we can do that fast enough to deal with those changes.
With the past decade as the warmest decade on record we are now starting to see the effects of climate change on our ability to produce food. Especially with 2010 already being one of the hottest years on record despite a solar minimum and a la nina.
And this is just one of the worst cases this year as we’ve had crop damages around the world. And with current projections on a business as usual scenario there’s a real risk that for example the United States will face another dust bowl.
These are serious issue we face, and for which we can take action that will prevent worse and can reverse the effects. The question is, will we respond fast enough.