2019 was a turbulent year for the aviation sector - to put it mildly.

The arrival of the Boeing 737 MAX had been expected to boost profits at airlines around the world and so its grounding after two fatal crashes put many of those firms under intense pressure.

"Boeing and the aviation industry had gambled very heavily on the 737 MAX being the next big thing, the advanced sales were enormous," said Eoghan Corry, editor of industry publication Travel Extra.

"Once that was grounded growth in the aviation industry came to a halt and it didn't take long for that to impact directly on Irish passengers and indeed on Irish tourism."

Irish customers suffered most through the end of transatlantic services from Norwegian Air and WOW Air.

Perhaps less obvious, however, were the services that never arrived at all.

"Air Canada were due to launch a new service from Toronto into Shannon, that didn't happen," said Niall Gibbons, CEO of Tourism Ireland. "That was a blow from a regional perspective not to have that particular flight."

Tourism Ireland is predicting modest growth for this year - owing in part to these kinds of cuts - as he warns of "choppy waters" in the international market.

Part of the reason for that is the lack of new capacity that is coming to replace what was lost - another consequence of 737 Max grounding. But other issues are at play too.

Coronavirus is like to have a negative impact on tourism worldwide - while Brexit continues to cloud over the Irish market, despite Britain's formal exit finally taking place last week.

Meanwhile there's another growing global trend - so-called flight-shaming; where people avoid taking flights due to the carbon footprint involved.

For an island nation heavily reliant on tourism any shift away from air travel would be a big problem - something that Tourism Ireland is keenly aware of.

"There is a risk that's there and I think what we'll have to utilise our image as a green, clean destination," Mr Gibbons said. "Ireland is a viewed as a place that's environmentally very positive, warm and engaging, and I think we'll have to use those assets to our advantage over the coming years."

According to Clare Dunne, managing director of the Travel Broker, customers aren't for the most part expressing much of a concern about carbon.

But almost all of the travel firms she deals with are preparing for it to become a big issue.

"We haven't had very many people looking to see what are they doing but the companies themselves - the suppliers themselves - are all working really hard," she said.

"Everybody's aware of it and they're all working on sustainable fuel, all of the airlines are trying to reduce waste onboard, reduce plastics on board, reduce the weight of the aircraft so they use less fuel and use more fuel-efficient aircraft," she said.

"Most companies are doing something," she stressed.

Others are focusing their energies on ethical projects - like employing disadvantaged people or ensuring that small communities benefit from the tourists they bring to their countries.

She says the industry ultimately needs to keep working on reducing its environmental impact - while also highlighting the other ways in which its impact is positive

"Obviously I'm biased, I work in the travel business, but I think we have to travel," she said. "We don't want to go back to the days when we didn't get off this island - we need to see new people, new places and experience different places.

"I think it's vital for the development of Ireland as a country to be able to get out there and meet new people... and we can't get off the island unless we're going to swim, we need to fly or we need to go on a ship," she added.