General · 21st February 2007
Does burning wood for heat increase global warming? On Cortes, probably not.
The most important consideration is whether you are using wood faster than grows back each year. On Cortes, right now, we aren't.
NATURAL CARBON CYCLE
Trees are part of the natural carbon cycle. Regardless of what you do with a single tree, all it's carbon is going to be recycled back into the atmosphere eventually. A ten year old alder that has just fallen will probably be fully released in less than a decade. A prime tree that will live another 200 years will not release all it's carbon for several centuries. If you cut more wood than grows back each year then you are increasing the CO2 in the air in the short term. You are also increasing global warming in the short term. The long term all depends on how many trees grow back.
ROTTING VS BURNING
Once a tree is down, both burning and rotting will release most of its carbon into the atmosphere as CO2. When trees rot, they are eaten by micro-organisms that release C02 in the process. Rotting takes much longer than burning. A rule of thumb is a fallen tree takes about as long to rot as it took to grow. Smaller diameter wood that is already down is probably the closest in impact to just rotting.
New research shows that at least for some forests, as much as 90% of the carbon is locked in the soil...not the trees. Heavy cutting of trees exposes this soil carbon to sun and water and it all starts to rot fast. So heavily logging an intact, shaded forest quickly releases far more C02 than just what is in the trees.
SOOT AND MELTING GLACIERS
Again new research is suggesting that tiny particles from smoke may be settling on glaciers and darkening them enough to significantly speed up their melting. On the other hand soot in the air may have a cooling effect.
GETTING MOST HEAT PER CO2
Burning dry wood with lots of oxygen produces the most heat per pound of CO2. The newest wood heaters with catalytic inserts or gasification systems that re-burn the smoke also dramatically increase heat per pound of CO2 released.