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Higher levels of CO2 have another major benefit for plants. The stomata are the pores on each leaf that absorb CO2. They have to be larger when the level of CO2 is lower. This allows more evaporation of water. With higher levels of CO2 the stomata are smaller and lose much less water. Some of the most important new plant growth is along marginal areas on the edges of deserts where new plants are making major inroads because they can now survive on much less water.