Rising Carbon Dioxide Levels Could Halve Amount of Water Plant's Release Into the Atmosphere

By Nikki Bruce - 06 Mar 2011 13:16:1 GMT
Rising Carbon Dioxide Levels Could Halve Amount of Water Plant's Release Into the Atmosphere

Enjoy basking in the cool shade of an old oak tree in the height of summer? Well, according to American and Dutch scientists it could soon be a less effective way of escaping the heat from the sun. A new study has found that as a result of rising carbon dioxide levels, plants are releasing less water into the atmosphere.

The report is printed in the new issue of the Proceedings of the National Academy of Sciences and the discovery was made by scientists at Indiana University Bloomington and Utrecht University Netherlands.

According to the scientists, who studied both living plant samples and samples of collections over  100 years old from around the Florida area,  carbon dioxide levels have risen by about 100 parts per million over the last 150 years. This has had an adverse affect on the rate that plants are releasing water into the atmosphere.

In order to release water, plants use a structure known as stomata (similar to pores). This allows them to absorb carbon dioxide from the air, which is then transferred into energy using the plant's natural processes. Part of this process means that the plant releases water into the atmosphere via the stomata, this is also known as transpiring which aids the plants' roots in absorbing water and also helps to cool the plant. Also whilst the plant is cooling, the air around it is often a lower temperature due to the water being released. Therefore if plants are transpiring less, then the traditional respite from the heat, provided by an old oak, might not be what it used to be.

It is thought that the carbon dioxide levels in the air have had an effect on the way plants transpire because it has caused the number and the size of the stomata on each plant to decrease. Plants, and in particular land plants, play a crucial role in both the carbon cycle and the  hyrdrogeologic (water) cycle and it is estimated that if today's carbon dioxide levels double, which is expected, then the amount of water in the air could be halved.