Johannes Lehmann studies biochar and its Brazilian precursor, Terra Preta, which the Indigenous peoples created thousands of years ago by charring household waste and burying it. This creates extremely fertile black soil, which does not degrade for many centuries, but sequesters carbon in the soil indefinitely. Today’s farmers can benefit from biochar as an “amendment” to their soil. This is useful both as a way of improving the productivity of farming (so as to feed the extra billions of humans who will be born in this century), and a way of removing carbon from the atmosphere and sequestering it permanently. Biochar has been found to be the most cost-effective and beneficial agricultural method for combatting climate change. However, it can be mis-used, so the user must follow the instruction on the labels. Unfortunately, there is almost no market for biochar yet, since the general public has not become familiar with its benefits. One proposal is to require fertilizer manufacturers to include a certain percentage of biochar to their product, since this will enable the farmer to use less fertilizer, though biochar itself is not a fertilizer. it simply enables more of the nitrogen, phosphorus, and potassium to be retained in the soil.