Current Global Diets And Future Global Warming
Agriculture is responsible for a large amount of global greenhouse gas (GHG) emissions. For example, raising animals is a notorious methane emitter, farm machinery and transportation are associated with significant carbon dioxide emissions, and fertilizer use is a major source of nitrous oxide.
Estimating the precise climate impacts of the global food system is challenging, mainly because each GHG acts differently when it comes to warming the earth. Carbon dioxide and nitrous oxide can stay in the atmosphere for centuries, while methane warms the earth quicker but only remains in the atmosphere for about a decade.
Another research challenge is that many studies use measures of “global warming potential” and “carbon dioxide equivalent” to estimate the GHG emissions of various activities. However, these measures don’t always account for how GHGs change over time. They also look at emissions over a set time period, which can make some GHGs appear more or less impactful than they truly are.
The aim of this study was to provide a more detailed understanding of how our current dietary habits will contribute to global warming by the year 2100, if no changes are made. The researchers collected enough data to build an inventory of GHG emissions for 94 food items, which they broke down into groups — grains, rice, fruit, vegetables, ruminant meat, non-ruminant meat, seafood, dairy, eggs, oils, beverages, and other. They also looked at current food consumption levels across 171 countries per the UN Food & Agriculture Organization.
Once they gathered this data, the researchers modeled the future impacts of today’s food consumption habits through computer simulations of different population growth scenarios. In addition to investigating the overall climate effects, they were able to state which food groups have a bigger environmental impact than others and which mitigations could be introduced to reduce the climate impacts of food.
The findings showed that the current global food system emitted 4,860 million tons of carbon dioxide, 151 million tons of methane, and 9 million tons of nitrous oxide in 2010. If no changes are made to worldwide dietary patterns, global temperatures may increase an additional 0.7°C to 0.9°C by 2100, depending on global population growth. This is largely because of methane, responsible for 60% of the warming caused by food consumption.
Ruminant meat and dairy combined were found to be responsible for over half of the projected warming by 2100, while rice would account for 19%. This is likely to be an underestimate of contributions since it is based on current consumption levels. In reality, demand for meat and dairy products is expected to continue to grow.
According to the authors, if we continue with business-as-usual food patterns, then global temperature increases may exceed the 1.5°C increase as set out by the Paris Agreement for the year 2100. However, the authors modeled potential solutions to reduce the harms threatened by food consumption. These include:
- Changes in dietary habits: By reducing ruminant meat and limiting chicken meat, fish, and egg consumption, expected temperature increases could be lowered by 21% (or 0.19 °C) by the end of the century.
- Reducing food waste: If retail and consumer-level food waste were cut by 50%, end-of-century temperature increases could be lowered by 0.04 °C. However, the authors note that a great deal of food waste happens before it reaches retail and consumers, so finding ways of reducing earlier food waste could prove even more beneficial.
- Improving production processes: By implementing changes to certain harmful food practices (e.g., using technology to improve manure disposal, reduce methane from cows, or change how rice is grown), 25% or 0.2°C of temperature increases may be prevented by 2100.
The study demonstrates that global food consumption, particularly meat and dairy intake, cannot continue at the current rates if we want to prevent climate change. Animal advocates can use this information to campaign for legislation favoring plant-based diets and reducing food waste. They can also remind the public that raising and eating farmed animals is a climate-taxing process, even if efforts are made to improve it. Ultimately, this is yet another study showing the dire need to shift away from meat-heavy diets as a way to protect our planet.