The global food system is an important contributor to greenhouse gas emissions that are responsible for climate change. Animal agriculture is responsible for a large share of the food- system emissions, both directly and through the production of animal feed.(1) Limiting global warming to the goals set forth by the international community will not be possible without rapid phasing out of animal-source food.(2)(3) Given population growth, is there a path for food system development that can be consistent with global demand for calories and protein without jeopardizing climate goals? Here we show that the rapid adoption of alternatives to animal-source foods, such as plant-based, cultured, or fermentation-derived, is consistent with climate goals, especially when combined with the transition to healthier diets and agricultural yield improvements.(4) Alternatives must achieve parity with animal-source foods, which means matching their price, taste, and other attributes. Delaying the introduction of alternatives at parity, even by a few years, makes a big difference in total greenhouse gas emissions from the food industry. To our knowledge, this is the first study to quantify greenhouse gas emissions across a variety of scenarios involving the transition from animal-source foods to alternatives in a global context and across all food groups. Moreover, we carefully model the transition to alternatives using conventional product adoption modeling. Our results point to the urgent need for large-scale acceleration of innovation in alternatives to animal-source food to achieve parity as soon as possible in order to allow for rapid adoption of such alternatives in time to limit global warming to 1.5 degrees C by 2100 with a 66% probability. For such acceleration, policy interventions analogous to those provided for alternative energy are needed to create innovation-friendly environment