International tourist arrivals grew by 6% to 1.4 billion last year, ahead of previous forecasts.
The UN World Tourism Organisation had predicted in 2010 that the milestone would no be reached until 2020.
However, the “remarkable growth” in tourism in recent years has brought it two years ahead.
Stronger economic growth, more affordable air travel, technological changes, new business models and greater visa facilitation around the word have accelerated growth in recent years.
The UNWTO forecasts international arrivals to return to growth of 3%-4% this year, more in line with historic trends.
The global economic slowdown, uncertainty related to Brexit, as well as geopolitical and trade tensions may prompt a “wait and see” attitude among investors and travellers, the organisation said.
It noted emerging trends such as the quest for ‘travel to change and to show’, ‘the pursuit of healthy options’ such as walking, wellness and sports tourism, ‘multigenerational travel’ as a result of demographic changes and more responsible travel.
Secretary-general Zurab Pololikashvili added: “Digitalisation, new business models, more affordable travel and societal changes are expected to continue shaping our sector, so both destination and companies need to adapt if they want to remain competitive.”
The Middle East (up 10%), Africa (7%), Asia and the Pacific and Europe (both 6%) led growth in 2018.
Arrivals to the Americas were below the world average with a rise of 3%, according to the latest UNWTO world tourism barometer.
Pololikashvili said: “The growth of tourism in recent years confirms that the sector is today one of the most powerful drivers of economic growth and development.
“It is our responsibility to manage it in a sustainable manner and translate this expansion into real benefits for all countries, and particularly, to all local communities, creating opportunities for jobs and entrepreneurship and leaving no one behind.
“This is why UNWTO is focussing 2019 on education, skills and job creation.”
International tourist arrivals in Europe reached 713 million in 2018, a rise of 6% increase over an “exceptionally strong” 2017.
But results in northern Europe were flat due to the weakness of arrivals to the UK.