A report on the future of travel and tourism, co-authored by a travel agency called Intrepid Travel and The Future Labs Institute, posits a future deeply impacted by climate change and restrictions on tourist travel to combat it.

From the report (pardon the length, emphasis added):

"Carbon Passports

A personal carbon emissions limit will become the new normal as policy and people's values drive an era of great change.

As demonstrated by a worldwide tourism boom, the frequency at which we can fly is once again seemingly unlimited.

Conscience and budgets permitting, we feel free to hop on planes from one place to the next. But this will change. 'On our current trajectory, we can expect a pushback against the frequency with which individuals can travel, with carbon passports set to change the tourism landscape,' says Raymond [Martin Raymond, Future Laboratories co-founder]