|Clear-cut at Ausjaurliden, Norrbotten. Seen from road 45, Photo: BM|
Wood can be used to replace energy-intensive materials like concrete, and biofuels from forestry can replace fossil fuels. This is how the forestry industry argues that forestry can help save us from climate change.
A lot of energy is needed to make paper and pulp products - over 20% of Sweden's energy is used in the forestry industry. These products typically have short lifespans and do not store carbon for a longer period like a wooden house can do. Over 80% of all forest products in Sweden are in this category.
In intensively managed forests, soil scarification and fertilization are used routinely. Soil scarification after clear-cutting leads to increased carbon emissions from the soil. The older the forest, the more carbon is stored in the soil. It can take more than 100 years for the carbon stocks in a forest to return to the state before harvest. Fertilization may increase the rate of carbon sequestration initially but does also contribute to large emissions of nitrous oxide (N2O). Nitrous oxide is a 300 times more potent greenhouse gas than carbon dioxide which can offset the cooling effect from forest carbon sequestration.
Replacing fossil fuels with forest-based bioenergy is not necessarily a good idea either, in part because such biofuels are not carbon-neutral, and in part because we need to reduce our energy consumption anyway. Cutting down forests in order to, for instance, continue to drive around in cars in cities is not sustainable since we have to stay inside all planetary boundaries at the same time.
The time aspect is important. If a forest is harvested and is used to produce paper or biofuels, carbon is released to the atmosphere and it takes many decades for new trees to sequester the amount of carbon which was released. Managed forests store less carbon than old natural forests as well. Fossil fuels are non-renewable and contribute with "new" carbon to the carbon cycle but biofuels are at least as bad for the climate, yielding the same amount of greenhouse gases. The atmosphere does not differentiate between the origin of the carbon dioxide. In a 100 year perspective biofuels may have even larger climate impact than fossil fuels. Within a few decades tipping points may be reached if we do not cut down drastically on releasing greenhouse gases now.