How bad is conference travel for climate change?
Spoiler: Quite bad
Conference travel in the U.S. emits 3% of all the carbon emitted by the United States each year.
A story in three numbers
To calculate this estimate, we need three key statistics:
Number of conference trips taken each year in the U.S.
Average amount of carbon dioxide emitted per trip
Percentage of total carbon emitted by the U.S. each year
Let’s take a look at each one.
Trips to U.S. conferences each year: 85 million
According to a 2016 study by the Events Industry Council, approximately 85 million conference trips were taken annually in the United States before the COVID-19 pandemic (Oxford Economics, 2016). This does not include travel for business meetings and other meetings—only conferences and trade shows (i.e., conferences with exhibit halls). And according to the Events Council’s 2023 report, we’re almost back to pre-pandemic levels of conference travel, so let’s assume 85 million trips.
Carbon emitted per trip: 2 metric tons
The figures for carbon emitted per traveler vary quite a bit, depending on where the conference is located and where attendees are coming from. International flights typically emit much more carbon than domestic, because the United States is geographically isolated from most other countries. Moreover, air travel is the most prevalent mode of transportation for international attendees.
Gattrell and colleagues analyzed the carbon emissions from attendees to four large medical conferences, some in the U.S. and some in Europe. They found a range in the average carbon emitted per traveler, from 1.2 to 4.2 metric tons. Across all four conferences, the average was 1.7 metic tons.
According to an analysis published in 2020 in Nature, the American Geophysical Union’s conference in San Francisco—with 28,000 attendees, a large conference with people coming worldwide—emitted the equivalent of 80,000 metric tons of carbon dioxide. This means the average attendee emitted 2.9 metric tons of carbon.
(BTW, the studies cited above used metric tons (1000kg) as their unit, which is almost the same as a ton (2000 lbs).)
Carbon for conferencing: 170 million metric tons
Using 2 metric tons of carbon dioxide emissions as the average for each conference trip and 85 million trips, we get an estimate of 170 million metric tons for conference travel each year.
What does all this add up to?
Conference travel = 3% of all U.S. emissions
According to the U.S. Environmental Protection Agency, the nation emitted 5.6 billion metric tons of carbon dioxide in 2021 (after accounting for carbon sequestration from the land sector).
That means that conference travel alone is roughly 3% of all emissions coming from the United States. These gatherings for 3-4 days are responsible for a notable fraction of all the carbon emitted by the country.
Anyone from Chicago?
Here’s another way to look at it: 170 million metric tons is more carbon than the entire city of Chicago and its surrounding suburbs emit in a year.
What can we do?
Hold virtual conferences some of the time. Even just alternating between virtual and in-person conferences would cut the climate emissions in half. The good news is that virtual conferences are getting better and better, with spatial platforms that allow people to mix and mingle, activities that pull people into engaging discussions, and thoughtful social norms that make everyone more comfortable turning on their camera and interacting. Will you join us?
Josh Gutwill is Co-Director of the Clean Conferencing Institute.
