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Climate-Regulating Forests

and the Trillion-Trees Drive

Motivated by a heightened state of awareness on climate change, tree planting is in high demand. Much attention has been drawn to trees as being efficient and inexpensive sinks for excess carbon dioxide in the atmosphere[i]. In order to find space to accommodate large numbers of trees, deforested areas - where soil and climate conditions allow for spontaneous forest regrowth - have been considered, excluding areas used by agriculture and other non-forest natural ecosystems. The sinking of CO2 is important, but it plays a smaller climate role when compared with the direct, powerful influence that trees have on water and energy cycles.

Trees are 400 million year old, carbon-sequestering technological marvels that offer a myriad of other yet more important services to environmental stabilization

In the hope that the worst effects of climate change be averted in time, considerable resources have started to be poured into tree-planting. But how fast can greening schemes be deployed? What kind of effort is required to counteract the present exponential speed of climate degradation?
All carbon-containing greenhouse gases together answer for around 20% of warming, while water vapor alone answers for up to 80%. Controlling water vapor is thus critically important. Only trees and forests have what it takes to convert water vapor from warming into a cooling agent.

The large-scale planting of trees is within humanity’s grasp. The climate emergency requires a sort of coordinated war effort, targeting appropriate areas.

In 2019, Ethiopia – a country with a population of a little over 110 million – set a world record by planting 353,633,660 trees, or roughly 3 trees per habitant, in just 12 hours of daylight. Applying the same planting rate on a worldwide scale, humanity would be potentially capable of planting 24 billion trees per day or, if there was a global collective effort, one trillion trees could actually be planted in less than two months! But what would happen to those billions of trees after the mad dash planting-day was over?

China is a world leader in planting trees. In the last 30 years, tree saplings were planted there on more than 800,000 km2, an area equivalent to the extent of deforestation in the Brazilian Amazon over the last 50 years. Nonetheless, a study of satellite images indicate that less than 15% of the saplings planted in China grew into a new closed-canopy forest[ii]. High mortality or sprawling, stunted development are common outcomes of greening projects when they are undertaken without careful consideration of climate and eco-hydrological limitations. Random tree planting might well grab the headlines, but it consumes much-needed resources without leading to the climate and environment stabilization we so desperately need.

[i] (Bastin et al., 2019)

[ii] (Ahrends et al., 2017)

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