Trees and plants, in general, are being used by the planet as one of the ways of keeping its temperature constant. A normal tree can evaporate almost 38 L of water daily, acting as a natural air conditioner for it’s surroundings. So trees, are important not only for their ability to keep the carbon dioxide in check, but also to keep the atmosphere at a lower temperature (through evaporation).
However, when the level of carbon dioxide is too high, it makes the pores from which the leaf perspires to close, hence making the entire process slower than usual. A study made by the researchers from Carnegie Science Institute, SUA, shows that more than 1/4 of the warming caused by the high levels of CO2 from the atmosphere is due to this effect.
These effects were known for a long time, according to the co-author of the study, Ken Caldeira, from the Global Ecology Department. Together with their colleague Long Cao, they saw that there isn’t too much light shed on the case that carbon dioxide can harm the planet, and through its effect directly on the plants.
Some older studies, made by Chris Field and Joe Berry, also from Carnegie, have indicated that the effects are major: “There is absolutely no doubt that carbon dioxide decreases cooling through evaporation of the plants and that this slow cooling process adds up to global warming”, said Cao. “This effect might have caused a significant warming even if carbon dioxide wouldn’t have been a greenhouse gas”.
In their model, the researchers have doubled the carbon dioxide concentration from the atmosphere and have registered the warming’s magnitude and geographic model through different factors. What they’ve discovered regarding the warming up of a certain area, was that on a planetary scale, the effects of plant’s evapoperspiration occupy approximately 16%, and the green house effect the rest. In some regions however, like parts from North America orEast Asia, these effects can represent more than 25% from the total warming.
“If we think that doubling the carbon dioxide causes 4 degrees Celsius extra, in a lot of places three from those degrees come from the carbon dioxide effect from the atmosphere, and one comes from the direct effect it has on plants.
The model presented by the Carnegie researches shows that the excess of CO2 will increase in most areas. Water that comes from different forms of precipitations will not pass thorough it natural process of evaporation within plants, and will flow directly in streams and rivers. None of the older models have provided surface flows as being caused by the changes of evapoperspiration caused by the high levels of carbon dioxide.
Studying the way plants respond to different concentrations of carbon dioxide, might help climatic predictions, and improve the representation of different climate models on the globe.