Positive Side of Carbon-dioxide....???

Yes, at first sight it can surprise. This is Nature, it has a deep meaning behind its every move....Same is with the CO2. The increasing levels of CO2 in the atmosphere has the big positive effect other than increasing global-warming. What is it???

In high school, we learned about 'photosynthesis' in which CO2 plays a major role. The main factors which affects this process are -- favorable temperature, the level of light intensity, and availability of CO2. The increased concentration of photosynthesis in the atmosphere can affect the growth of plants by affecting its rate of photosynthesis. It is hidden secret in the climate change debate that the vegetation and plants can actually benefit greatly from increased CO2 levels.

How?

There are plenty of examples to show that if CO2 levels increase more than the present 360ppm, then most plants would grow faster and larger because of more efficient photosynthesis and a reduction in water loss. Higher levels CO2 can benefit the plants in several ways.Some of them are -- 

-- greater resistance at extreme temperatures.

-- better growth at low light intensities.

-- improved root/shoot ratios.

-- less harm from air pollutants.

-- more nutrients in soil as a result of more nitrogen fixation process.

There are two important reasons for this productivity boost...First, superior efficiency of photosynthesis and second, sharp reduction in water loss per unit area of leaf. The pores (stomata) of leaves are the respiration channels of the plants but they are also responsible for the transpiration or moisture loss from plants which leads to the need of more water to the plants. Higher levels of CO2 partially closes these pores hence lowering the moisture loss, it can be quite significant in the arid climates.                             

The biggest variation differences in response to CO2 in plant species are among -- C3, C4, and Crassulacean Acid Metabolism or CAM -- each with a different pathway for photosynthesis fixation of carbon dioxide.Most green plants, in forests that account for two thirds of global photosynthesis, algae, and most major food crops are C3 plants.C3 metabolism allows them to respond most dramatically to higher levels of CO2.

Cereal grains with C3 metabolism, including rice, barley, wheat, oat, and rye  show yield from 25%-60%. Rice (the most eaten food in the world) has shown increase in mass with less water and higher CO2 levels. The benefit C4 plants receive is from higher CO2 levels is reduced water loss by about 33% through leaf pores (stomata). The examples of C4 plants are corn, sugarcane, sorghum, millet, some tropical grass and etc. These plants grow under higher temperatures and limited soil moisture, they can show high yields of 10-55% even when there is low rainfall.

Evidences

In most green plants, productivity continues to rise up to CO2 concentrations of 1000ppm and above. In an indoor garden with the carbon dioxide amount increased from an ambient level of 300ppm to a high level of 2000ppm can nearly double plant growth. Experiments have shown that plants can handle up to 10,000ppm of CO2 with no ill-effects on maintaining all plant resources at maximum and at a temperature not exceeding 30deg.

Department of Energy(DoE) examined the responses to elevated carbon-dioxide levels in gum trees. DoE pumped tonnes of CO2 into the plots, raising concentration of CO2 in the trees. The average increase was 24%. Fine root and wood production has also increased. These fine roots are very important for water and nutrient absorption.

A Russian study from 1961-1998 found that as carbon dioxide increased the forest increased at same rate. Pine trees grown for 2yrs at 600ppm, grow more than 200% faster than normal. Trees and seedlings grown under controlled environments or in open top simulating the outdoors have shown remarkable growth responses to elevated levels of CO2. Michigan State University has produced plantable trees in months, rather than years, by subjecting seedlings to 1000ppm CO2 under optimal conditions.

A standard  practice for laboratory scientists working with algae cultures to conduct their research in CO2-enriched environments. They cut costs by shortening their season and better crops. For over 100 years, nurserymen around the world have been adding carbon dioxide to their greenhouses to raise the yields of vegetables, flowers, and ornamental plants. These vegetables are tomato, cucumbers, lettuce, show early maturity, more no. of fruits, bigger size and reduction in riping time. Greenhouse grown flowers including roses, have shown early maturity with longer stem, long-lived and more colorful flowers. Increase in yield is 9%-!5%.

Good or Bad

So far we have seen that increase in carbon dioxide concentrations increases plants growth and its abundance. Its still early time and somewhat misleading to say that, if CO2 is good plants, its good for environments also. Research says, higher level of CO2 in atmosphere promotes to trees more rapidly, resulting in more no. of trees and therefore wood per year, but, with the higher temperatures there are also more pests.

Researchers and scientists says that doubling of CO2 would increase plant productivity by growing faster, bigger in size, increase in leaf size and thickness, more stem height, branches and seed production. No. of fruits and flowers would be also on a rise. Root system would also improve by nitro-fixation.

Out of 21 of the most important crops 17 falls under C3 category, and C3 are mostly trees. Since, C3 plants benefits more than C4 from higher carbon dioxide levels so, we can expect reforestation and enormous expansion of biomass. C3 plants includes rice, wheat, barley, chickpeas, potato, field beans, soybean, banana, coconut, sugar beet etc. On the other hand, 14 out of 18 most noxious weeds are C4 plants, and C4 grows slow with higher CO2 levels.

Plants and trees (forests) directly and indirectly produce 95% of the food, for human beings and also for birds and animals. Birds and animals are totally depended on the plants for their food. The increase in plants would also control or rather regulate the population of animals. 

Increase in carbon dioxide concentrations may not be good for environment. But, We don't know how far or to what extent, all  the predictions and assumptions made related to higher level of CO2 are true. We do not know any optimal level of CO2 should be in atmosphere. Many predictions and assumptions made in the early centuries have proved wrong about the ecological system and existence of earth itself. But, increase in plants means more forestation, more no. of trees, resulting more food production and the decline in food prices can be expected. If the no. of trees increase, the nature itself could balance the temperature levels keeping the environment clean and cool. But, again, CO2 also contributes to rise of temperature levels and it we can't afford to ignore this...