Manuel Enrique Figueroa, from the University of Sevilla, directed the a project that calculated how useful certain tree species were to able to absorb CO2 during their growth process. Growing trees, according to him, is a simple yet effective (up to a certain point, of course) way to achieve this.
The species they studied were from Western Europe, but they affirmed that they could be extended to other species around the world. Do you want to see the rank and how many tons of CO2 they can absorb per year? Follow us after the jump (the picture is from the winner).
The winners are two varieties of pine trees: the Aleppo Pine (pinus halepensis), able to capture an average of 48,000 CO2 kg per year and the Stone Pine (pinus pinea): 27,000 kg CO2 per year. Remarkably, a popular Mediterranean tree such as the Cork Oak (quercus suber) can "only" capture 4,500 kg.
Species planted in cities have lower ratings, in general, because they tend to be smaller trees. A type of ash tree (Melia azedarach) is the best performer: ten trees on a street are able to offset CO2 from 10,373 vehicles per year. The worst performers were Acacias (offsetting just 1,619 cars), Jacarandas (1,405 cars) and Elm Trees (1,320). Take these numbers prudently, they didn't mention the car models and you can presume they didn't use V8s for calculation purposes.