The Tree Carbon Calculator

Why do we need to know how much carbon is stored in trees?

Trees remove carbon dioxide from the atmosphere and store (sequester) it as carbon in the plant material and in the surrounding soil. Over the last 300 years or so, the activities of humans (such as the burning of fossil fuels, and vegetation clearing) have lead to a large increase in the concentration of greenhouse gases such as carbon dioxide in the atmosphere. These greenhouse gases trap longwave radiation from the earth’s surface and heat the planet. Although this is a natural process, and allows the earth to maintain a fairly constant temperature which allows life to exist, scientists believe that this human-induced increase of greenhouse gases will lead to global climate change (‘global warming’), possibly resulting in more extreme weather patterns – more cyclones, floods and droughts. Global warming may be combatted by removing CO₂ from the atmosphere and temporarily (for the tree’s life) storing the carbon, however forests can only offset a relatively small proportion of total greenhouse gas emissions, and so we must also reduce our industrial emissions at the same time.

Want to know more?

• The Greenhouse Effect
• Enhanced Greenhouse Effect
• What is a carbon sink?
• Why are carbon sinks important?
• How can sinks help combat global warming?

  

How does a tree carbon value relate to the amount of carbon I contribute to the atmosphere?

Compare the amount of carbon stored in your tree to the amount of carbon you emit in your day-to-day activities in Australia.

ACTIVITY	CARBON emitted (kg)	CO2 equivalent (kg)
1 year’s use of family sedan sized car	1,200	4,400
1 year’s household electricity consumption	2,200	8066
1 return flight from Sydney to Melbourne for 1 passenger	70	256

On average, in 2000 each individual Australian contributed approximately 7.7 tonnes of carbon (28.2 tonnes of CO₂-e) to the atmosphere.

In total, Australia as a whole contributed 146 million tonnes of carbon to the atmosphere in 2000 (or 535 million tonnes of CO₂-e).

Australia’s heavy reliance on fossil fuels for electricity generation means that this source alone contributes a large proportion (32.7%) of our greenhouse gas emissions to the atmosphere each year. The 9.8 million cars on Australian roads also make up a significant proportion (8.0%) of our greenhouse gas emissions.

Sources of data for these calculations

Explaining CO₂-e (carbon dioxide equivalents)

Different greenhouse gases have differing abilities to warm the planet (“global warming potential”). To enable us to estimate how much a given mass of greenhouse gas is estimated to contribute to global warming, the gas is compared to a baseline of one unit by weight of carbon dioxide (CO₂), and is expressed in “carbon dioxide equivalent” (CO₂-e). Many scientists also calculate the amount of carbon stored as carbon (C). To convert to CO₂ or CO₂-e, multiply by 44/12.

For example, methane (CH₄), another common greenhouse gas, has a global warming potential 21 times that of CO₂.

Australia’s greenhouse gas emissions

The following documents from the Australian Bureau of Statistics website (http://www.abs.gov.au) were used to calculate estimates of an individual’s greenhouse gas emissions:

• 2001 Motor Vehicle Census, Australia (9309.0)
• 2001 Census – Australia’s big picture (2015.0)
• Energy and greenhouse gas emissions accounts, Australia 2001 (4604.0)

Other data sources were:

• National Greenhouse Gas Inventory (2000) Fact Sheets 1 and 2, Australian Greenhouse Office, 2002. (http://www.greenhouse.gov.au).
• National Greenhouse Gas Inventory (2001). “Analysis of trends and greenhouse indicators 1990-1999”. Australian Greenhouse Office.