Between food waste and impacts of agriculture, it's about one-third of our carbon footprint
By University of British Columbia
A new study from the University of British Columbia suggests
that moderation should not be limited to one season. The research found that 44
percent of people worldwide would need to change what they eat if global
warming is to be held below 2 °C.
The study was led by Dr. Juan Diego Martinez during his
doctoral work at UBC’s Institute for Resources, Environment and Sustainability.
He explains what the research revealed and outlines practical diet changes that
could help reduce climate risks.
What did you find?
The analysis shows that about half of the global population,
and at least 90 percent of Canadians, would need to adjust their diets to avoid
the most severe levels of planetary warming. Martinez notes that this estimate
is cautious because the study relied on data from 2012. Since that time, both
greenhouse gas emissions and the global population have continued to grow.
Projections for 2050 indicate that roughly 90 percent of people will need to
eat differently.
The researchers examined data from 112 countries,
representing 99 percent of food-related greenhouse gas emissions worldwide.
Each country’s population was divided into 10 income groups. The team then
calculated a food emissions budget for each person by combining emissions from
food consumption, global food production, and supply chains. These totals were
compared with the maximum emissions the planet can sustain if warming is to
stay below 2 °C.
Why focus on dietary changes rather than, say, flying less?
Food systems account for more than one-third of all
greenhouse gas emissions caused by human activity.
The study found that the top 15 percent of food-related
emitters are responsible for 30 percent of total food emissions. That amount
matches the combined emissions of the bottom 50 percent of the population. This
high-emitting group is made up of the wealthiest individuals in high-emissions
countries, including the Central African Republic, Brazil, and Australia.
While these top emitters contribute heavily, many more
people still consume diets that exceed the recommended emissions limit. This is
why the issue extends beyond the richest groups. Globally, half the population
needs to change their diets. In Canada, all 10 income groups are above the
emissions cap.
Discussions about flying less, driving electric, and buying
fewer luxury goods are valid: We need to cut emissions anyway we can. However,
food emissions are not just a problem for the richest—we all need to eat, so
everyone has the ability to make a difference. For people who both fly
frequently and eat large amounts of beef, it is not an either/or choice:
Reducing both can help.
What changes can we make to our diets?
Start by eating only what you need and finding ways to reuse
leftovers. Reducing food waste lowers emissions, cuts down on cooking, and
makes meals simpler and more enjoyable.
Another key step is cutting back on beef. In Canada, beef
alone accounts for 43 percent of food-related emissions for the average person.
Martinez points out that if countries had followed the commitments set out in
the Kyoto Protocol, beef consumption might not pose such a challenge today. At
this stage, however, food emissions must also decline to avoid the worst
impacts of climate change.
Martinez acknowledges that this shift is difficult. He says,
“I grew up in Latin America where eating a lot of beef is part of the culture,
so I get how much of an ask this is.” Still, he stresses that the evidence is
clear and can no longer be ignored.
Using Everyday Choices to Push for Change
He encourages people to “Vote with your fork.” Individual
choices are a starting point for broader action. As more people talk openly
about how their diets are changing and why it matters, political leaders are
more likely to support policies that improve food systems and reduce their
climate impact.
Reference: “Dietary GHG emissions from 2.7 billion people already exceed the personal carbon footprint needed to achieve the 2 °C climate goal” by Juan Diego Martinez and Navin Ramankutty, 11 November 2025, Environmental Research: Food Systems. DOI: 10.1088/2976-601X/ae10c0
