The Numbers Behind the Growth
Global tourism emissions climbed from 3.7 gigatonnes in 2009 to 5.2 gigatonnes in 2019, according to a comprehensive study published in Nature Communications. That represents a 40% increase over the decade, pushing tourism's share of worldwide emissions from 7.3% to 8.8%.
The annual growth rate of 3.5% for tourism emissions outpaced overall economic expansion by more than double during the same period. Every dollar spent on travel generates 30% more carbon than the average economic activity, and four times more than the service sector as a whole.
While the pandemic briefly interrupted this trajectory in 2020 and 2021, the rebound has been swift. At current rates, tourism emissions will double within two decades.
Where the Emissions Come From
Aviation accounts for half of all direct tourism emissions, making it the most stubborn obstacle to meaningful change. Decades of industry promises about technological fixes have failed to materialize at the scale needed to offset surging demand.
Ground transportation powered by petrol and diesel contributes 17% of the total, while utilities such as electricity supply add another 16%. The pattern is clear: technology improvements are happening, but they cannot keep pace with the expansion in travel volume.
The study, which draws on data submitted directly by 175 governments and uses the UN-endorsed measurement framework for sustainable tourism, represents the most detailed accounting of travel-related carbon yet compiled.
A Concentrated Problem
The concentration of emissions among a small group of nations is striking. The United States, China, and India together were responsible for 39% of total global tourism emissions by 2019, and they drove 60% of the growth during the study period.
Expand the view to the top 20 countries, and you capture three-quarters of all tourism emissions. The remaining 155 nations share just a quarter of the footprint. Per-capita differences now span a hundredfold gap between the highest and lowest emitters.
The US alone carried a tourism carbon footprint of nearly one gigatonne in 2019, equal to 19% of the global total. That breaks down to roughly three tonnes per resident, placing it 12th globally in per-capita terms but first in absolute scale.
The UK ranked seventh as a destination, producing 128 megatonnes and 2.8 tonnes per resident. Australia, at 82 megatonnes, came in 14th overall but eighth per capita at 3.4 tonnes, largely driven by the long distances inherent in reaching and leaving the country.
New Zealand showed a similar pattern, with 3.1 tonnes per resident. Both nations face the structural challenge of geography: international visitors and outbound travelers alike must undertake long-haul flights that carry outsized carbon costs.
What Needs to Change
The UN Environment Programme has set clear benchmarks: global emissions must fall 42% by 2030 and 57% by 2035 to keep warming within 1.5 degrees under the Paris Agreement. Tourism, moving in the opposite direction at speed, presents a widening gap between ambition and reality.
For the first time, tourism appeared on the agenda at COP29 this year. UN Tourism acknowledged the 8.8% emissions share and framed the moment as a turning point toward action. Yet the study's findings underscore how steep the climb remains.
Four pathways emerge from the research. First, measure emissions rigorously to pinpoint the sectors driving growth. Aviation, energy supply, and vehicle use must move onto a 10% annual reduction path through 2050.
Second, define what sustainable growth actually means. The 20 highest-emitting destinations need national strategies that set thresholds and avoid excessive development.
Third, shift the market mix. Encouraging domestic and short-range travel while actively managing demand for long-haul flights offers the most direct lever for change. That could involve regulation, pricing, or both.
Fourth, address inequality. The social cost of carbon falls unevenly across countries, and controlling the relentless expansion of long-haul air travel aligns with a fairer distribution of both opportunity and burden.
The Policy Challenge
Technology alone will not solve this. Efficiency gains in aircraft design, fuel composition, and operational practices have been swamped by the sheer volume of additional flights. The same dynamic plays out across ground transport and energy use.
The purpose of the research, according to the team, is to give policymakers and industry leaders clarity about the scale of the problem. Evidence is no longer the missing piece. What comes next is political will, regulation, and a willingness to make choices that slow growth in some areas while redirecting it toward lower-impact alternatives.
The study's scope, spanning 11 years and drawing on government data from 175 nations, provides a baseline that was previously unavailable. It also makes the stakes harder to ignore. If tourism continues on its current trajectory, the sector alone will consume a growing share of the shrinking carbon budget the world has left.
