CARBON SEQUESTRATION AND CARBON SINKS

A carbon sink is a reservoir that stores more carbon than it releases, over an indefinite period of time. The main natural carbon sinks are plants, the ocean and soil. However, carbon sinks can be made artificially, for example, by capturing CO2 and storing it in the ground or ocean bed. Carbon sequestration is this process of capturing and storing atmospheric carbon dioxide, long-term. It is one method of reducing the amount of carbon dioxide in the atmosphere. The aim is to either mitigate or defer global warming and avoid dangerous climate change.

CARBON GEOLOGICAL SEQUESTRATION

This is where biochar comes in. If biomass is not converted to biochar it naturally degrades, contributing to greenhouse gases. Instead, biochar may be added to soils with the intention to improve soil functions and to reduce emissions from biomass otherwise naturally degrading into greenhouse gases. Furthermore, when natural ecosystems are converted to agricultural land, most carbon in the soil is lost to the atmosphere, as soil microbes decompose. If biochar is returned to agricultural land it can increase the soil's carbon content permanently and would establish a carbon sink for atmospheric CO2.

DOES IT REALLY WORK?

Studies of the unusual fertility of soil in the Amazon suggest that indigenous populations thousands of years ago produced a kind of biochar. 'Slash-and-burn' methods use open fires to reduce biomass to ash, whereas 'slash-and-char' uses low-intensity smouldering fires covered with dirt and straw, for example, which partially exclude oxygen. Slash and char, rather than releasing CO2 into the atmosphere, sequesters carbon for thousands of years. While subsea and rock sequestration are currently very new technologies: high tech and high risk, soil sequestration is more down to earth. Making minor changes to agricultural methods could make the world of difference.