This might come as a shocking revelation to many of you. Quite a sizeable amount of population clearly underestimates the imminent threat that global warming poses, assuming the more quantity of carbon dioxide is beneficial for the plants. But as the old saying goes, “anything in excess is bad”. And now various recent researches show this to be quite true.
Earlier, it was assumed by a majority of people, even many scientists that higher percentage of carbon dioxide in the atmosphere would provide better nourishment for the plants. This hypothesis is only partially true i.e. the assumption cannot be based on solely the increase of CO2, without taking the other factors that also depend on it for consideration.
A study shows that excess of carbon dioxide reduces the rate of transpiration of plants. This is so because the stomata openings of the leaves, used for exchanging both gases, and water vapour get smaller. As the lesser volume of water gets evaporated by the leaves, the lesser volume is absorbed from the ground, thus causing an increase in runoff water.
Due to increasing pollution, ground-level ozone volume has been found to increase as well. O3 or ozone is only beneficial in the upper layers of atmosphere and is toxic at lower levels. Its reaction with increased CO2 causes damage to the internal tissues of the leaves. This leads to decreased growth of the plants as well photosynthesis.
Another study shows the effect carbon dioxide would have on plants if its concentration is doubled, which is expected to occur in the next hundred years. In this study, the plants were grown with the concentration of CO2 to be 610 parts per million as opposed to the present 340 ppm. Plants in the former condition were found to produce no more weight of vegetation than the ones today. Furthermore, it was found that plants exposed to higher carbon dioxide content formed massive amounts of starch grains on their uppermost leaves. When starch grains get accumulated in the chloroplasts, it hinders its functioning and slows down photosynthesis. It basically causes the leaves to exhibit abnormal behaviour. Also, the amount of nitrogen in the leaves was found to be a bit lower than the present concentration.
Increased carbon dioxide has also created a problem of land fertility degradation. This excess CO2 has increased the fine root structure of the plants. This leads to almost doubling o f the carbon dioxide in the soil in which they grew, leading to the loss of important nutrients of the soil.
Quality of food crops is affected as well due to increased CO2 levels. For e.g-It inhibits the ability of the wheat crops to convert nitrates to proteins. Trace elements are affected as well, with the percentage of iron decreasing and that of lead increasing. This would have a drastic impact on the overall health of the world, half of which is already iron deficit. Excess lead is quite dangerous for the human body. There is an overall decrease in the quality of the food crops.
There are many other indirect ways that excess CO2 has an adverse impact on the growth of crops. With increased levels of carbon dioxide, plants would require a higher quantity of fertilizers to compensate for the degrading soil fertility. A higher production of artificial fertilizers would be required to keep up with the crop production. This, in turn, would put a higher pressure on the other natural resources such as natural gas, driving their prices up as well.
As we know, global warming has been increasing the earth’s overall temperature. This escalation would eventually cause an increase in the number of deserts worldwide, disturbing the whole ecosystem that would try to migrate towards the pole for optimum conditions.
Another interesting thing that has been observed is that with increased carbon dioxide levels, the defences of the plants go down. They become more susceptible to insects. It has been compared with the conditions that were prevalent around 55 million years ago, when there was a rapid jump in global carbon dioxide levels. Researchers have found it to be the reason for increased foraging of the plants by insects.
In conclusion, many studies have been conducted regarding this topic and all of them show more-or-less the same result-our earth can simply not handle any more levels of CO2. Many scientists even speculate that the plants might be near their saturation point already where they cannot remove the carbon dioxide any faster than they are doing right now. In the coming future, the amount would become too much for even the plants to reduce global warming. Hence, it is the best if we start to keep a check on the amount of carbon dioxide that is being released into the environment due to various human activities. Just another sign that tells us the impending threat of global warming.