The importance of trees in controlling the global carbon cycle is very often neglected. We keep hearing about extensive deforestation projects, forest fires and cutting of thousand years old trees for the properties of their wood or simply because they are in the way of a big highway construction project. But are we really aware of the influence these trees have on our climate?
Scientists have established long ago that forests are the most important component in the carbon sequestration process. Annually, trees remove more carbon from the atmosphere through the process of photosynthesis than they release back through respiration and decomposition.
This is how trees have controlled the levels of carbon dioxide (CO2) in the atmosphere in the past, despite the numerous attempts of humanity to make the challenge for trees harder through burning of fossil fuels.
But, is it possible to estimate exactly how much CO2 is removed from the atmosphere and sequestrated in the soil only by global forests? Unfortunately, the answer remains negative. Even with all the advances of modern technology, scientists are still unable to measure the exact dimensions of forested areas on the planet. The size of individual tree trunks, the weight of the roots, and even the annual change in biomass, still present a problem, despite the numerous satellite remote sensing sensors orbiting the planet.
The best guess is that nearly a third of the total CO2 released in the atmosphere from burning of fossil fuels has been absorbed by trees. Scientists have made quite a few attempts to quantify the so-called carbon “sink” through assessment of change in live biomass, dead wood, organic matter, and harvested wood products in parts of the world.
An international initiative took these factors to estimate forest carbon stocks and fluxes for the years between 1990 and 2007. Although such study is bound to be associated with quite large uncertainties, the team of researchers was able to establish that around 4 billion tonnes of carbon per year is sequestrated by global forests.
In addition, only in the tropics, forests absorb 2.8 billion tonnes of carbon per year, which greatly increases the significance of these areas. Unfortunately, these parts of the world are also associated with the most severe deforestation.
There is no doubt that protecting and preserving the forests is our best bet if we want to mitigate climate change. In theory, everybody knows that, but in practice, we seem to choose not to remember.