Pace of adoption of alternatives to animal-source foods is an important factor in reaching climate goals.

The global food system is a significant contributor to greenhouse gas emissions that drive climate change. Animal agriculture accounts for a large share of food-system emissions, both directly and through the production of animal feed. Global population growth and rising incomes imply a further increase in demand for animal-source foods if current trends persist. Limiting global warming to the targets set by the international community will not be possible without the rapid reduction of a substantial share of animal-source foods. We show that the rapid adoption of alternatives to animal-source foods, such as plant-only diets or plant-based, cultured, or fermentation-derived analogs to animal products, can be consistent with climate goals while satisfying global demand for calories and protein. Importantly, timing is crucial: the longer the delay in adopting alternatives, the larger the share of the diet that must shift away from animal-source food by 2050 for the food system to remain within its carbon budget.