CO2 emissions make the planet greener but drier

In Australia l’aumento della copertura arborea provocato dall’anidride carbonica sta riducendo le risorse idriche.

The large quantities of carbon dioxide we emit in the atmosphere contributing to alter global climate, have real effects on trees and plants. In fact, CO2 plays an essential role in the photosynthesis process of these organisms.


Australian forest


On the one hand, CO2 stimulates trees to grow, on the other hand it makes them “thirstier”, leading them to absorb more water from the soil, taking it from rivers. In Australia, water shortage is a serious problem that risks getting worse due to rising temperatures. A study reveals that the country lost about one fourth of its water flows over the past 30 years, a phenomenon that has been exacerbated by plants’ water need linked to their growth, which is stimulated by CO2.


The research, carried out by Anna Ukkola, researcher of the Macquarie University of Sydney, and published by Nature Climate Change magazine, has analysed 190 Australian river basins, examining satellite images and linking water scarcity to the increasing greenery due to carbon dioxide rising levels.


Researchers found that in greener areas there’s less water. In general, the “greening” process triggered by CO2, which registered an increase of 14% since 1980, is responsible of having reduced river flows by 28%.


LEIGH CREEK, AUSTRALIA - JUNE 7:  Stockman Gordon Litchfield from Wilpoorinna sheep and cattle station surveys the bottom of a dry dam on his property on June 7, 2005 in Leigh Creek, Australia. Australia is enduring its worst drought in decades and with the combined affect of increasing temperatures and the El Nino weather phenomenon there appears no sign of abatement.  (Photo by Ian Waldie/Getty Images)
Drought in Australia © Ian Waldie/Getty Images


The research shows that rising CO2 levels can have 2 opposite effects on water resources, depending on the reaction of small pores on leaf surface, called stomata, which allow plants to control CO2 absorption and water loss.


On the one hand it can make plants more resistant and adaptable. By result, they would need lower amounts of water to produce the same surface of vegetation. This would favour farmers that have large amount of water.


However, in Australia’s arid areas, water flows reduction exacerbates the current harsh situation of water resources, and put farmers on their knees, since they rely on streams for irrigation.


fiume in australia
River in Australia


“While there are clearly some positives for growth found by this research, it also shows us that some of our crucial agricultural areas will not see these benefits because of the future impacts of climate change on rainfall,” concluded Ukkola.

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