I still don't fully grasp the climate impact of lumbering (unless its purpose is burning the wood for energy or making space for pastures which is obviously bad). Is cutting down trees and making or constructing something from them good or bad for the climate? Deforestation is supposed to be detrimental for the environment, but Finnish researchers suggest we shift from steel and concrete to wood in our building construction. It's gonna cost us all trees in the world considering the population growth and urbanisation, isn't it?
Oh yes it is very useful.
Let's consider you have an old forest, something in which the trees have grown very large so if you choose to chop them down, you get a very high share of sawlog and very low share of pulpwood.
There are three sustainable things you can do to it:
- Leave the forest there. The trouble is, the forest is already at equilibrium, so any carbon sequestered is matched by carbon dioxide from decomposing. Climate benefit of that particular forest is exactly zero.
- Chop down the forest, and use all of the wood as pulpwood. Financially this is a very poor decision, because pulpwood has a far lower price than sawlogs. However, this is still more sustainable than leaving the forest there, because at least the pulpwood substitutes for packaging materials that would have otherwise been made out of oil (plastics). However, the packaging materials created from the pulpwood are rapidly burned for energy, so they don't retain their carbon for long. So the only climate benefit is from substituting for oil use. At least you get some climate benefit.
- Chop down the forest, attempting to make the sawlog percentage as high as possible. The sawlogs are maximally used for creating permanent carbon sinks and used for furniture, houses, etc. You can expect them to retain the carbon for 100 years. You will still get a small pulpwood share, but that has climate benefits too: it substitutes for oil use. Also you will get sawdust etc that can be burned for energy (substitutes coal use in heating in cold climates), or be used to make biochar (it retains most of the carbon while still producing some energy for heating although less than if it was burned directly to energy).
In cases 2 and 3, you will obviously plant a new forest that during its rapid growth stage is a very efficient carbon sink. By removing the old forest, you retained its carbon maximally, while at the same time created room for new forest to grow. Forest is always limited by room: if there was infinite room on this planet, there would be no climate crisis as we would just plant exponentially increasing amounts of new forest to capture emissions from exponentially increasing fossil fuel use.
So you can see that chopping down the forest and maximizing the sawlog percentage, building something from the wood, maximizes the climate benefit.
Deforestation per se, without replanting trees to compensate for the trees felled, is bad for the environment.
Replacing steel and concrete with lumber/timber from trees for construction purposes is an old concept of sustainability. The manufacturing of steel and concrete is very energy intensive and the manufacturing of both currently produces a lot of carbon dioxide.
In producing steel, currently carbon, in the form of coal, is added to the molten iron ore to remove oxygen from the melt. Basically the chemical equation is iron oxides + carbon gives iron + carbon dioxide:
FexOy + C -> Fe + CO2
There are new processes to produce green steel/iron by using hydrogen instead of coal (carbon) to remove the oxygen from the melt. Such a process would produce water vapor instead of carbon dioxide.
FexOy + H2 -> Fe + H2O
Getting the hydrogen is the tricky part. Currently plans are in place to use electricity from renewables, and hydro electricity to produce hydrogen and oxygen via the electrolysis of water.
The process of manufacturing cement for concrete involves roasting limestone (CaCO3). This produces carbon dioxide.
Using lumber from trees, instead of steel and concrete, avoids the production of vast quantities of carbon dioxide. The tree plantations that were felled to produce construction lumber can eventually be replaced by replanting the forest plantation. This is a more sustainable and less environmentally damaging way of producing construction material.