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Deforestation, Lumber And Carbon Emissions


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Some thoughts on an early Monday morning after I returned from an earth science conference in which much was made of deforestation and carbon emissions (rightfully so). During one session of this conference, lumber use (i.e. logging) got a very bad rap when it came to carbon emissions, because (as is well known) trees remove CO2 from the atmosphere - and add oxygen - as long as they are alive. But I decided to do some research of my own this morning to check their numbers when it came to logging.

To start:

Total global forest cover = 3,869,455,000 hectars or 3.87e+13 square meters as of year 2000 (http://www.mongabay.com/general_tables.htm)

Annual forest growth = 500 grams/square meter on average (http://www.rff.org/documents/RFF-DP-97-37.pdf)

When multiplied by global forest cover, annual forest growth = 1.94e+16 grams/yr.

Annual global deforestation = 7,317,000 hectars or 7.32e+10 square meters annually during 1990-2005 (http://rainforests.mongabay.com/deforestation.html)

Average growing forest density is 800 grams/square meter so:

Annual global deforestation = 5.85e+14 grams/yr.

Average annual global lumber harvest = 53 grams/m2 (http://www.rff.org/documents/RFF-DP-97-37.pdf).

When multiplied by the rate of deforestation we get:

Annual lumber harvest = 3.88e+12 grams/year.

This assumes that lumber is harvested uniformly from all areas that are being deforested - so it is probably an overestimate of the amount of timber that is being converted into lumber, because hauling logs from forest to sawmill requires roads (but agricultural deforestation does not).

OK - (drum roll) - so the annual production of lumber (3.88e+12 grams/year) is 0.66% of the total mass of forest that is being cut down on a yearly basis. And this is probably an overestimate. This means that something like 99% of the world's forests are cleared for agriculture or ranching - meaning, the wood is burned.

Interestingly, the proportion of forest cleared by logging (estimated above) is at least 10-20X less than estimated by one environmental group (http://rainforests.mongabay.com/0803.htm).

Burning of wood releases ~1000 kg of CO2 per cubic meter (dry). So for each guitar you make (1-2 board feet per instrument) you keep 3-6 kilograms of CO2 out of the atmosphere (so please do not burn your guitars when you're done with them!).

Commentary welcome.

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