Biochar is biomass burned in the near absence of oxygen and it is basically identical to charcoal, but used for different purposes. It is being widely promoted by various interests as a soil amendment and to sequester carbon, often with little detailed argument or evidence in support of the claims made.
The book "Biochar for Environmental Management" provides of a large collection of articles about biochar by a total of some 50 researchers and specialists from a wide range of universities, government departments and companies. It demonstrates clearly that there are major gaps in knowledge. However, at the same time, some writers speak of biochar as a means to address climate change and propose it for carbon markets, in spite of these knowledge gaps.
Few would deny that agriculture is especially severely affected by climate change and that the right practices contribute to mitigate it, yet expectations of the new climate agreement diverge sharply, as well as notions on what are good and what are bad agricultural practices and whether soil carbon sequestration should be part of carbon trading.