Despite the many challenges in achieving complete decarbonization of our energy supply, succeeding in that Herculean task would solve merely two-thirds of our greenhouse gas emissions problem. This chapter addresses how we might tackle the other third. Topics covered include: fugitive methane emissions from fossil fuel production; CO2 emissions from both traditional and industrial biomass combustion; emissions of CO2, methane, and nitrous oxide from the agricultural sector; CO2 emissions from land use changes and the forestry sector; the full range of greenhouse gas emissions from the industrial sector unrelated to energy; and the ongoing release of methane from our waste streams. Tackling these diverse and myriad emission sources will greatly tax the ingenuity and budgets of humanity.