Recently there have been calls for tree planting on a colossal scale to capture CO2 and curb climate change. However, whilst young trees are efficient and effective carbon sinks, the same is not so true for mature trees. The Earth maintains a balanced carbon cycle – trees (along with all other plants and animals) grow using carbon, they fall and die, and release that carbon again.

Many pine trees in managed forests, such as the European spruce, take roughly 80 years to reach maturity, being net absorbers of carbon during those years of growth – but once they reach maturity, they shed roughly as much carbon through the decomposition of needles and fallen branches as they absorb. As was the case in Austria in the 1990s, plummeting demand for paper and wood saw huge swathes of managed forests globally fall into disuse. Rather than return to pristine wilderness, these monocrops cover forest floors in acidic pine needles and dead branches. Canada's great forests for example have actually emitted more carbon than they absorb since 2001, thanks to mature trees no longer being actively felled.

Arguably, the best form of carbon sequestration is to chop down trees: to restore our sustainable, managed forests, and use the resulting wood as a building material.