The world’s 2.5 billion poorest people - small farmers living at the far fringe of the developing world – and their billion or so slightly better off neighbors burn 10.5 billion metric tonnes (tonnes) of crop waste annually. Smoke from their fires reddens the sun, closes airports, shuts schools and governments – and kills millions of people (World Health Organization (WHO). who.int/health-topics/air-pollution#tab=tab_1). Their fires release 16.6 billion tonnes of CO2, and emit 9.8 billion tonnes CO2e, 1.1 billion tonnes of smog precursors and 66 million tonnes of PM2.5. (Akagi et al., Atmospheric Chem Physics 4039-4071, 2011; Environmental Protection Agency, epa.gov/ghgemissions/understanding-global-warming-potentials; Food and Agriculture Organization, FAOSTAT, http://www.fao.org/faostat/en/#data) [See Attachments 1–3. For details of the Attachments, please see the section below entitled “Availability of data and materials.”]. No one yet has stopped the burning. Seminars, health warnings, bans, threats, jailings, shootings – nothing has worked, because not one has offered farmers a better alternative. This is the story of how Warm Heart, a small, community development NGO, learned enough about small farmers’ plight to collaborate with them to develop the technology, training and social organization to mobilize villages to form biochar social enterprises. These make it profitable for farmers to convert crop waste into biochar, reducing CO2e, smog precursor and PM2.5 emissions, improving health and generating new local income – in short, to address the big three SDGs (1, 2 and 3) from the bottom.