Old growth forests as carbon sinks

The traditional wisdom (see papers here) has been that forests sequester CO2 from the atmosphere during their active growing phases (up to year 80 in most broadleaf species) but once maturity has been reached CO2 is no longer absorbed but simply stored.

Now a paper has been published in Nature (2008) which shows that old growth forests accumulate carbon over the centuries not just the active growth phase.

30% of the planet's surface is covered by old growth forests and this research suggests that between 0.8 and 1.8 billion tonnes of CO2 is stored annually.

These forests were also excluded from calculations in the Kyoto protocol. It is now clear that ancient forest sinks need to be included in carbon balance calculations.

It doesn't mean than ancient forests will save us from catastrophic climate change - it does mean that if we don't protect them properly even more CO2 will be released into the atmosphere than we originally thought.