co2 and plants

10 August 2019
Climate change

A few weeks ago, Weather Eye in The Times of London had a short piece beginning, 'something strange is happening to plants: their leaves seem to be growing thicker. And the cause is increasing amounts of carbon dioxide in the  air.' You may be a keen gardener, or even a farmer or small holder, and you might have noticed this. On the other hand you might not have noticed anything unusual as we are talking about a very thin layer of thickness. Never the less – it is a nice story. Plants, we are told, have become a bellweather for increasing co2 levels becuse they use the gas for photosynthesis, capturing it and turning it into food using sunlight and water. Without co2 plants would die – and so would we. In other words, co2 is a vital ingredient of life on Earth.

The problem, we are informed, is that once plants get thicker leaves they do not appear to cool the air as much as when water evaporates through leaf pores. The hypothesis then is that more co2 is left in the atmosphere instead of being absorbed and stored by plants – according to a study in the journal Global Biogeochemical Cycles. This is something that has been logged by examining old herbareum species which  seem to have fewer pores – going back over the last 200 years. Conveniently, this is roughly the beginning of the industrial revolution in a small corner of the world. One might also note that it is roughly the same point that global temperatures came fully out of the Little Ice Age. Weather Eye usually has a more nuanced approach but in this case seems to support the article down to the last full stop. The theory is that more co2 in the atmosphere leads to fewer pores in plants and more luxuriant growth. One may also hypothesize that co2 also causes more plants to grow – which is why less pores are necessary. One also wonders why the positive benefits of more co2 are not broadcast in media (print and air waves). After all, farmers pump co2 into their greenhouses, (plastic or glass), in order to achieve a greater crop yield. Yet, the media appear to demonise co2 as if it was a poison, taking a cue of course from the environmentalist lobby. Yet the science is quite clear. It is a fact that co2 is beneficial. The idea it is going to warm the planet is a theory that has yet to be proved. It is more logical to look at the Earth as system that has evolved over millions of years. In that scenario co2 would have been part and process of that evolution.

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