Short answers, pulled from the story.
One quarter of the world's greenhouse gas emissions result from food and agriculture according to data collected in 2019. The agriculture forestry and land use sectors contribute between 13% and 21% of global greenhouse gas emissions.
A single cow will emit 220 pounds of methane per year. Methane production by animals principally ruminants makes up an estimated 15-20% of global production of methane.
The IPCC Sixth Assessment Report was published in 2022 stating that diets high in plant protein and low in meat and dairy are associated with lower GHG emissions. This report also stated that shifting to diets with higher plant protein shares could lead to substantial decreases in GHG emissions.
Nitrous oxide and methane make up over half of total greenhouse gas emissions from agriculture. Agricultural processes comprise roughly 80% of nitrous oxide emissions and virtually all carbon dioxide emissions tied to land use.
A 2023 study found that a vegan diet reduced emissions by 75%. Changes to a diet less reliant on animal products such as plant-based diets are also effective for reducing greenhouse gas emissions.