Radical realism. A managed decline of fossil fuel production. The countries that signed the Paris Agreement pledged to keep global warming below 1.5 degrees Celsius. In order to comply with that objective, there is a maximum amount of CO2 we can emit. This is our carbon budget. However, there is a huge gap between how much fossil fuel we can burn and how much fossil fuel countries and companies are planning to extract. Burning all the oil, gas and coal embedded in existing fields and mines would by far exceed that carbon budget. And even if global coal use ended overnight, burning all the oil and gas in developed reserves would still push global warming beyond 1.5 degrees Celsius. We are beyond the point where we can phase out one fossil fuel at a time. If we want to keep global warming below 1.5 degrees Celsius, we need a managed decline of fossil fuel production. That means, first, stopping new fossil fuel exploration and extraction immediately. Second, shutting down existing fossil fuel extraction projects. Third, committing to a just transition by affording fossil dependent workers and frontline communities a viable future. Radical realism for shifting towards an economy powered by clean energy means ending fossil fuel production through a governmentally managed decline of fossil fuel exploration and extraction.