Global Climate

Trees ARE Carbon

Trees don't just absorb carbon from the atmosphere, they ARE carbon from the atmosphere. Roughly half of a tree's biomass is carbon from atmospheric CO₂, while the rest is mostly hydrogen and oxygen, which comes from water. Except for trace nutrients in the soil, trees don't eat anything. They grow by drinking water and breathing.


A typical tree stores the carbon from 5-10 metric tons of CO₂. (Click to see the calculation)

  • First consider the volume of the wood above ground for two representative trees. We will approximate this volume as a cylinder, with volume in the branches making up for the taper of the trunk as one goes up in height.

    • Tree #1 is 60 ft. tall and has 24 diameter at breast height (d.b.h.) has a volume of 188.5 ft³ .

    • Tree #2 is 75 ft. tall and has 30 diameter at breast height (d.b.h.) has a volume of 368.2 ft³ .

  • The dry weight of oak wood is 34.94 lbs/ft³ [1].

  • Wood is mostly lignocellulose, which is 44.5% carbon, by mass.

  • CO₂ is 27.3% carbon, by mass.

  • A metric ton is 2204.6 lbs.

  • Stored CO₂ [metric tons] = Volume [ft³] × 44.5% ÷ 27.3% ÷ 2204.6

    • Tree #1 contains the equivalent of 4.9 metric tones of CO₂

    • Tree #2 contains the equivalent of 9.5 metric tones of CO₂

A typical human generates 4.5 metric tons of CO₂ per year.

A typical American generates 15.8 metric tons of CO₂ per year.

Gasoline Equivalent

A gallon of gasoline releases 20 lbs of CO₂, when burned.

So, that tree which held 10 tons of CO₂ is equivalent to 1,000 gallons of gas or 27,000 miles driven.

Big Old Trees Matter More

It's tempting to think that a tree's rate of carbon sequestration tapers off as the tree matures and stops growing vertically. This is false. Research shows that trees sequester carbon at an ever-increasing rate as they get older [2,3].

This is why is is imperative to preserve our large trees . Mitigating the loss of carbon sequestration by planting requires an absurd quantity of new trees, as artfully explained here by Bob Leverett.

References

  1. Weights of various woods grown in the united states, Technical Note Number 218 US forest service, July 1931

  2. Leverett, R., Masino, S., Moomaw, W. Older Eastern White Pine Trees and Stands Accumulate Carbon for Many Decades and Maximize Cumulative Carbon. Front. For. Glob. Change, 13 May 2021. Sec. Tropical Forests

  3. Stephenson, N., Das, A., Condit, R. et al. Rate of tree carbon accumulation increases continuously with tree size. Nature 507, 90–93 (2014).

  4. https://www.northeastforestcarbon.org/wp-content/uploads/2022/03/Measuring-Forest-Carbon.Securing-Forest-Carbon-Fact-Sheet5.final_.pdf