How many trees are there in the world?
Scientists from Yale and 23 other universities have been busy trying to answer this question for us kids from Plant-for-the-Planet. Just a short time ago, in September 2015, they revealed a definitive answer to this question – the earth has three trillion trees! At first glance, this seems like an enormous number. However, scientists also found out that we humans have already destroyed 46%, so almost half, of the trees that there once were. Furthermore, the study shows that we lose around 15 billion trees per year due to deforestation.
How many trees can we plant?
We kids from Plant-for-the-Planet have set ourselves the goal of planting a trillion trees worldwide by 2020 with the help of companies, states, and organisations. Our friends, the scientists, have shown us that there were once around six trillion trees in the world. Unfortunately there are only around three trillion of those left. So, we have enough room for one trillion new trees, without being in competition with agriculture and settlements and without needing to plant in deserts.
Why are trees so important?
Trees do a lot of work for us – they are irrefutably beneficial and super efficient:
Trees are the only extremely economical and super easy way of storing CO2. Scientists from Oxford University have said that planting trees is the best method for taking carbon dioxide out of the atmosphere and for combatting global warming. Trees are very easy to plant and, as years go by, they take CO2 out of the atmosphere and into long-term storage. On average, we calculate that each tree stores 10 kg of CO2 each year. In the tropics this figure is many times higher.
Trees regulate precipitation and are part of the water cycle. A big tree can take up to 370 litres of water out of the ground and release it into the atmosphere in a single day. Additionally, the leaves of trees capture water in the form of raindrops. This water then evaporates and, through cloud formation, causes precipitation in other places. This process is called evapotranspiration. Evapotranspiration causes around 40% of our average yearly rainfall.
Trees cool the earth by contributing to cloud formation. Forests, through the release of isoprene (a certain hydrocarbon), promote the formation of special clouds that cool the earth. The cooling takes place through the so-called albedo effect. Albedo refers to the ability of surfaces to reflect solar radiation. Clouds are one of these surfaces that reflect solar radiation. So, when we can contribute through worldwide reforestation to more solar radiation being reflected into space, we are actively working against the climate crisis.
Trees clean the air. Trees not only take in CO2 and other greenhouse gases like carbon monoxide or sulphur dioxide, but they also give off valuable oxygen. A single tree can take in up to 5 kg of air pollutants a year and produce up to 130 kg of oxygen over the same period.
With one trillion new trees, we would store over a quarter of our current worldwide CO2 output and gain valuable time to achieve the two degree target. For more information on how amazing trees are, click the link below for different studies and publications.