An alternative would be to collect wood material at a constant rate and then store it. Recently, it was argued that this large-scale planting action may also have a negative total climate effect since the greening of open land areas will reduce the albedo of the earth. Also, a possibility is modified harvest and management. Taking advantage of photosynthesis in forests requires global schemes for reducing deforestation in combination with planting and replanting programs. The annual sink of the world’s forests has been estimated to be about 2.4 GtC. However, the latter alternatives may involve high risk for unexpected drawbacks. Two other alternatives could be a large scale deployment of artificial photosynthesis, or to increase the carbon uptake of the oceans by adding active absorbers. Another option is to increase the carbon uptake by letting forest stands grow for longer periods. One alternative is to use the photosynthesis to increase the carbon sink by increased magnitude of the world’s forests. It is therefore important to consider alternative options. To contribute at this scale, the sequestrated amount of carbon by industrial CCS has to be of order 1 GtC/year or more, while the total amount of carbon stored so far is only a few tens of megatonnes, ie., a few per mille of the necessary amount. Hence, the new energy sources need to deliver up to 5 terrawatts (TW) or above. The scale of the problem should not be underestimated: to reach the less than two degree goal of IPCC, the annual CO \(_2\) emissions must be reduced from the current level of 10 GT of carbon per year (GtC/year) to 5–6 GtC/year by 2050. The cost of the capture process itself is estimated to be in the range of 40–70 euros/tonne CO \(_2\), depending on technology. Industrial CCS requires energy and costly facilities and the captured gas has to be transported and stored in stable geological formations. For CCS, a range of alternatives exist, each with its particular challenges. CO \(_2\) free energy requires a significant build-up of nuclear and/or renewable power production, which involves large initial economic investments. It will require a transition to CO \(_2\) free energy sources in many applications, and/or CCS from facilities such as fossil-based power plants. When also considering the projected population and consumption growth, the CO \(_2\) reductions needed are daunting. The results of this study indicate that carbon harvest from forests and carbon storage in living forests have a significant potential for CCS on a global scale.Īccording to the intergovernmental panel on climate change (IPCC), a reduction of the anthropogenic emissions of CO \(_2\) to the atmosphere is necessary to avoid global warming beyond two degrees. In addition, a large amount of wood, 11.5 GT of carbon per year, could be extracted for reducing CO \(_2\) emissions by substitution of wood for fossil fuels. The numerical experiments show that under a hypothetical scenario of globally sustainable forestry the world’s forests could provide a large carbon sink, about one gigatonne per year, due to enhancement of carbon stock in tree biomass. Here we develop a new simulation model to assess the global carbon content in forests and apply the model to study active annual carbon harvest 100 years into the future. The potential contributions from forests, forest products and other low-tech strategies are less frequently discussed. Discussions about limiting anthropogenic emissions of CO \(_2\) often focus on transition to renewable energy sources and on carbon capture and storage (CCS) of CO \(_2\).
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