From CLIVE HAMBLER
The idea that rainforests are a sink for carbon dioxide is very well
established among teachers and schoolchildren, to judge by applicants to
study biology at Oxford over the last two years. This view is reinforced
by statements such as ‘as we chop down the rainforests, we reduce the size
of the sink’. (Forum, 1 February). Is this true, or do they merely store
carbon?
Carbon fixation clearly occurs in a rainforest as trees grow. But plants
and animals in forests also respire, die and decompose, liberating the carbon.
Some carbon is being stored without oxidation beneath some of these forests,
but are the quantities and timescales of such fossilisation of carbon significant
compared to the rate of release from fossil fuel and biomass combustion?
Like pupils and teachers, I would like to believe that the greenhouse
effect presents an argument for protection of intact forests, but I am unsure
of the relative scale and rates of the processes involved. Until sufficient
data exist to clarify whether the forests are effectively neutral with regard
to the short term carbon budget, we should not risk causing confusion and,
worse, crying wolf.
Clive Hambler University of Oxford
Advertisement
