Increasing amount of planet-warming greenhouses gases such as carbon dioxide in the atmosphere has been linked to man-made climate change, which threatens to alter ecological systems as we know it.
Dryer Amazon, Wetter Indonesia And Africa
A new study now predicts another set of phenomena that may happen as a result of increasing amount of greenhouse gas in the atmosphere.
Climate models used in the study, which was published in the journal Nature Climate Change, predict that the rise of atmospheric greenhouse gases could lead to a dryer Amazon rainforest and wetter woodlands in Indonesia and Africa in the future.
"Nearly all models from the Coupled Model Intercomparison Project Phase 5 predict a strengthening zonal precipitation asymmetry by 2100, with relative increases over Asian and African tropical forests and decreases over South American forests," the researchers wrote in their study, which was published on April 27.
Study researcher Gabriel Kooperman, from University of California, Irvine, and colleagues showed how a seemingly small process impacted by the amount of carbon dioxide in the atmosphere can have significant effects.
Transpiration
Transpiration is a process by which plants absorb and distribute water through the roots and release water vapor through the leaves.
The stomata on the leaves open and close when plants take in the carbon dioxide that they need for growth, as well as release water vapor.
With higher amount of carbon dioxide, stomatal opening is not as wide and this can result in reduced amount of water evaporating into the atmosphere.
Drought And Increased Rainfall
Kooperman and colleagues said that the effect of this plant-level process, is magnified across the rainforest, and this can lead to atmospheric changes that can affect the flow of moisture and the way winds blow from the ocean.
As the forest evaporate less moisture into the air because of higher amount of carbon dioxide, Kooperman said that fewer clouds form above the Amazon. The mechanism can lead to drought unique for the Amazon as well as increased rainfall over forests in Central Asia.
Reduced evaporation can also result in warming over Indonesian islands, which include Java, Sumatra, and Borneo, that are encircled by humid air above the surface of warm ocean.
"You'll get a stronger contrast in heating over the islands compared to the nearby ocean, and so it will enhance a natural ocean-land breeze, pulling in more moisture from these neighboring ocean systems to increase rainfall over the forests," said Kooperman.
