Tourists could turn their back on traditional destinations and even opt to stay at home, the meeting on tourism and climate change was told Tuesday.
"Damage to tourist sites could cause severe job losses and economic disruption. The consequences for some destinations could be very serious," Secretary General of the United Nations World Tourism Organisation (UNWTO) Francesco Frangialli said.
"Climate change is not a remote future event for tourism," he added.
Holidaymakers could be discouraged from going away as they considered the potential environmental impact of their lifestyles and as some destinations lose their allure.
Tourism is said to account for five percent of all greenhouse gas emissions that are blamed for global warming, the bulk caused by transport.
Global warming poses a threat to coastal areas, which risk being overwhelmed by algae as a result of warmer seas, while ski resorts, particularly at lower altitude, are already suffering from less snowfall.
Shardul Agrawala of the Organisation for European Cooperation and Development (OECD) said the European Alps were particularly sensitive. Since the 1980s, warming in the Alps has been three times the global average.
An OECD report last December said an additional warming of one degree Celsius would lead to a 60 percent decrease in the number of "naturally snow-reliable" ski areas in Germany. Under a four-degree warming, practically none of those areas would remain viable ski resorts.
The 450 delegates attending the conference from governments, the tourism industry and environmental organisations, were told adaptation was a necessary step and would have to go hand in hand with mitigating efforts to reduce greenhouse gas emissions.
Sri Lanka announced at the meeting that it intended to become the first carbon neutral destination. The tiny country reliant on long haul travellers said it hoped to use its vast tropical forests that absorb carbon to offset its emissions.
It is the second international conference on tourism and climate change and is expected to set the agenda for a ministerial tourism meeting in London in November ahead of the UN Climate Change Conference scheduled for Bali, Indonesia in December.