Trees and plants are known for their ability to draw carbon dioxide out of the atmosphere, and up until recently, the net-global forest sink was estimated to be around 1.1 Petagrams (1015 g) of Carbon annually from 1990 – 2007. This has to take into account the additional carbon emitted due to land-use change and deforestation, however a new study determined that tropical forests are actually a significantly large carbon source rather than a carbon sink. This not only poses a problem for future atmospheric CO2 predications, but also disrupts current plans for curbing greenhouse gas emissions set by the Paris Climate agreement.
Putting aside whether or not countries will stick to these emission agreements, most nations expected the land sector to mitigate up to a quarter of their total pledged reductions by 2030. This drastic change in data now presents the issue of how to compensate for the extra carbon which countries initially expected to be absorbed naturally by vegetation. Dr. Alessandro Baccini states that the unexpected rise in human activity within forested areas has increased deforestation at a much faster rate than was predicated and is one of the leading factors for the substantially greater levels of carbon emission. Ultimately land degradation and disturbances accounts for 69% of the total carbon lost from tropical forests.
Changes in carbon density from 2003 – 2014. Source: Baccini et al (2017)
With such a drastic change in the overall outlook on the world’s net carbon exchange, “negative emission techniques” are being analyzed in greater detail in attempt to shift tropical forests back towards being a carbon sink. Two of the most common methods currently being used to replenish the carbon density within tropical forests are reforesting areas which have experienced heavy degradation as well as expanding current foliage areas (afforestation). Both of these methods aim the increase the rate of carbon withdrawn from the atmosphere and the total capacity for carbon the forests can retain. Estimates for these techniques suggest an average removal of 3.7 tons of CO2 per hectare of forest per year with an associated cost of $20-100 per ton.
Additionally, a relatively modern carbon-capture technique uses “Biochar” to offset CO2 emissions. Biochar is essentially a charcoal made from burning biomass while the supply of oxygen is cut off. This process named pyrolysis prevents the carbon accumulated in the matter before burning from breaking down at a normal rate. The resulting biochar is added to soils which helps distribute nutrients and water all while limiting carbon release into the atmosphere. This is a fairly primitive carbon storage technique, but its estimated that up to 4.8 billion tons of CO2 can be sequestered using biochar each year.
These are only a few examples of carbon reducing strategies, but seeing as the carbon is building up in the atmosphere at even quicker rates than have been predicted, more creative and drastic steps need to be taken to handle the issue in time. In terms of efficiently reducing/storing carbon and cost effectiveness, what other strategies could be pursued to help offset the carbon flux? Also, what implications could this have on future environmental policy including international agreements?