The crop residues that lie scattered across thousands of farmlands globally could be a brilliant secret weapon against climate change.
By turning these leftover husks, roots, and leaves into carbon-sequestering biochar, we could lock away up to 7 percent of total global greenhouse gas emissions for the next 100 years. That's roughly the equivalent of the aviation and shipping industries' combined annual emissions.
This extraordinary finding from a recent new study shows, in fact, that the potential of repurposed crop residues is so powerful that countries like India could use it to lock away the equivalent of over 40 percent of their current greenhouse gas emissions.
Largely, crop residues are either left to degrade on farmland, or they are burned, heaving emissions into the atmosphere. And yet the technology does exist to turn this raw material into biochar. Plenty of studies have shown biochar’s potential on small scales - but until now, the worldwide potential of farm waste, produced at industrial scales, was unknown.
As a national measure to mitigate greenhouse emissions - perhaps as part of countries’ nationally determined contributions towards our global climate goals - biochar could hold clear promise. At a global scale, the researchers’ more conservative estimates show that we could lock away at least 3 percent of worldwide emissions with this one approach, using this widely-available resource that might otherwise just be burned.
We urgently need to draw down excess carbon dioxide, the researchers say: “Making biochar from crop residues is one of the few tools we have that can do this at scale without competing for land.”