Forests - carbon sequestration systems ?

Question

- Is there a standardised system for measuring the carbon dioxide sequestrated by trees?
- If yes do you know anything about the differences between the various forest types in their sequestration rates?

Answer 1

Unfortunately there can not be a standard. The rate of sequestration depends on the growth rate which in turn depends on various factors including species. The usual limiting factor to tree growth is availability of water. An average sized tree uses about 1000l of water per day so over 50 years your tree will need 365 X 50 kilo litres. Once it stops growing it stops sequestering carbon but continues to release water vapour, another greenhouse gas.
Back when it was decided to lower carbon dioxide emissions not much was known about global warming.
Now we know that trees release 10 000 tonnes of water vapour for each tonne of Carbon dioxide sequestered. The water condenses quickly but not quickly enough. The net effect is that forests contribute to warming not to cooling and in the process remove valuable water from catchments. Still they are quite pretty.

Answer 2

The problem with global warming is that it is global. Forests transpire water to cool their relatively dark leaves. Without this they would cook. Naturally this phase change has a local cooling effect in daylight. Moving from the sun into the shade will naturally feel cooler. At night it is very different. Deserts cool very rapidly at night because of a lack of greenhouse gas, water! Forests do not, so they start each day with some of the heat from the day before. This is the essence of the greenhouse effect. Anything that contributes significantly to the global average of greenhouse gasses will promote warming. Water vapour can easily top 4% of the atmosphere; carbon dioxide has risen slowly to 0.04%. Changes in the absolute humidity or percentage of water vapour are the main drivers of the greenhouse effect. Forests absorb more heat from the sun than grasslands or deserts and dissipate this heat by evaporating massive amounts of water, the forest stays cool at the expense of the rest of the globe.
Forests evolved when the earth was much cooler; according to the Ghaia hypothesesis they functioned to warm the earth.
As the sun began to release more light grasslands evolved to counter the warming effect. If you are not into alternative hypotheseis then consider the laws of thermodynamics. Changing one parameter results in another change that tends to counter the first.
Many of us choose to believe that forests are benevolent or at least benign unfortunately nature is seldom like that and what we wish were true doesn't change measurable facts.
It can however lead to "solutions" that become part of the problem. Humans have always done that. That's how we get into such a mess.

Answer 3

Gary K is right about there being too many variables to give a difinitive answer to your question, but I disagree with what he says about forests releasing water vapor causing climate warming. Walk from a dessert into a forest on a hot sunny day some time and you will immediately feel much cooler. The water vapor does keeps the temperature in forested areas more even between day and night. Higher humidity equals more stable temperatures over 24 hour periods.

Answer 4

Thankfully, the US is a non participant in the sequestration program.