The carbon footprint of air travel to UN climate conferences has increased 25-fold over three decades

The annual United Nations Framework Convention on Climate Change Conference of the Parties convenes thousands of delegates from around the world to negotiate international climate policy, with participation relying heavily on long-distance air travel. Here, we estimate greenhouse gas emissions from travel by Party and Observer State attendees to every conference from 1995 to 2024 using the carbon R package and two datasets: a complete list of individual attendees from the first through the twenty-ninth conference, and global flight-route data (OpenFlights, 2014). Indirect emissions and well-to-tank emissions were included. Total emissions per conference were estimated by multiplying emissions per person per country by the total number of attendees and summing across countries. Emissions totalled 710,282 tonnes of carbon-dioxide equivalent over the study period, increasing by 2500% from the first conference (2959 tonnes) to the twenty-ninth (76,931 tonnes). Emissions per attendee were higher for conferences farther from Europe. Carbon emissions due to air travel have increased by 2500% between UN climate conferences COP1 and COP29, mostly due to increased participation, according to analyses of flight data and conference attendance data.