Recently, the World Resources Institute (WRI) released a report which they say quantifies the sources of greenhouse gases in the atmosphere (1). Strangely, they cite no studies within it and some of the values they provide differ substantially from those determined in careful studies conducted by others.
Farming, for example, is responsible for far more than the 12.3% of global warming that the WRI claims for it. Study after study indicates that agriculture is responsible for at least a quarter of that warming (see reference 2, which links to many more). If we count methane’s effects over its lifetime in the atmosphere, instead of averaging it over 100 years, it goes even higher than that (3).
Methane emitted today will be mostly gone just 12 years from now, but it is constantly being replenished, making it very reasonable to consider its instantaneous effects, not those from an imaginary disappearance of the gas from the atmosphere. Indeed, methane levels are rising, not falling (4).
We note, also, that the bulk of GHG emissions from agriculture come from animal farming, the growing of feed to support farm animals and deforestation and land use changes necessary for that industry (5).
It is possible that the WRI is estimating only direct emissions, ignoring the myriad other means by which agriculture, for example, contributes to global warming. Their wording indicates otherwise, though.
The methodology they are using should be much more clearly described. As written, their assessment is likely to lead people to seriously underestimate the need for dietary change in mitigating global warming and to make other errors, as well.
So, when you’re considering the effects of agriculture on the climate – and other aspects of the environment, don’t rely only on a single source. Check around and work from sources that reflect and cite a wide variety of high quality studies. Our World in Data* (see reference 2 below), will help you do that! You’ll then be able to form a picture of the subject you’re investigating that more closely reflects the reality of the situation.
1.https://www.wri.org/insights/4-charts-explain-greenhouse-gas-emissions-countries-and-sectors
2. https://ourworldindata.org/environmental-impacts-of-food
4. https://gml.noaa.gov/ccgg/trends_ch4/
5. https://www.science.org/doi/10.1126/science.aaq0216
*Our World in Data is a rigorous online scientific compendium that focuses on large global problems including poverty, disease, and climate change.The research team is based at the University of Oxford.
