The Intergovernmental Panel on Climate Change has released Climate Change and Land, a special report on how land management and use interacts with climate change, after the report was approved by the world’s governments. It emphasises the vital role that land use plays in climate change, both as a carbon source and carbon sink, with around 23% of total greenhouse gas emissions between 2005-2016 coming from agriculture, forestry, and other land use activities carried out by humans, though in net terms the effect is less than half of that. With the need to maintain food supplies to a growing global population, and also to preserve biosecurity, there are some limits to the cultivation of energy crops and afforestation for the purposes of reducing carbon emissions and storing carbon dioxide. However, both energy crops and afforestation will play important roles in action against climate change, and the message from the chairs of the IPCC working group struck a cautiously optimistic tone. One co-chair, Hans-Otto Pörtner, said that “land already in use could feed the world in a changing climate and provide biomass for renewable energy, but early, far-reaching action across several areas is required.” Soil erosion is one important risk which will increase with more intense rainfall, reducing the suitability of land for use, but another IPCC representative said that “sustainable land management is a way to protect communities from the detrimental impacts of this soil erosion and landslides’, though he added that “there are limits to what can be done, so in other cases degradation might be irreversible.” As with all climate change impacts, they are more severe with higher rates of global average temperature rises. At 1.5^oC, there is “an increase in risks from dryland water scarcity, fire damage, permafrost degradation and food system instability”, which at 2.0^oC become “very high risks related to permafrost degradation and food system instability”. However, coordinated action “can simultaneously improve land, food security and nutrition, and help to end hunger”, according to the press release.

For the combustion industry, most interest in the report will be associated with energy crops and afforestation, the latter of which is becoming an emissions offsetting strategy for companies such as Eni. The report states that, if applied “at scales necessary to remove CO₂ from the atmosphere at the level of several GtCO₂/yr, afforestation, reforestation and the use of land to provide feedstock for bioenergy with or without carbon capture and storage, or for biochar, could greatly increase demand for land conversion”, but that “integration into sustainably managed landscapes at appropriate scale can ameliorate adverse impacts”. A scale of use of several million square kilometres “could increase risks for desertification, land degradation, food security and sustainable development”. Eni’s plan for planting around 8.1 million hectares of forests would be 81,000 square kilometres, meaning that if the limit was something like 2 million square kilometres of land planted with forests, about 25 such projects would be possible. This is far under the suggestion from researchers at ETH Zürich earlier in the year that 17 million hectares of land could be planted with forest, but given it is thought that the world is currently losing trees on a net basis, whether 2 million or 17 million square kilometres of land could be planted with trees might be a question for a future year.