September - carbon storage
Without the capacity for long-term storage of carbon in our peat bogs, forests and oceans, the level of carbon dioxide in the atmosphere would be much higher than it already is today.
Of all the gases contributing to the ‘greenhouse effect’, the most important is carbon dioxide. Its concentration in the atmosphere has risen sharply in recent years, the result of burning of fossil fuels and changes in land use, such as deforestation and the conversion of grasslands to crop production.
Scotland’s biggest store of carbon (other than its coal and oil deposits) is in the peat which makes up our bogs that cover 1.8 million hectares. Almost 2 billion tonnes of carbon are locked up in these bogs. Undisturbed, healthy bogs continue to accumulate carbon at a rate of around 0.25 tonnes per hectare per year. This is, however, a fragile store and when bogs are drained or damaged it can result in the release of 2-4 tonnes of carbon per hectare per year.
Woodlands are also an important carbon store. Although trees store much less carbon than our soils, they capture it more quickly. The average accumulation rate over the life of a commercial forest is around 3 tonnes per hectare per year, some 12 times faster than of healthy bog.
In addition the phytoplankton in our seas capture large amounts of carbon dioxide through their photosynthesis and the production of their calcareous shells. When they die they sink to the deep ocean floor where the carbon dioxide can remain trapped for up to hundreds of years.
