(CNN) - Let's journey back to a different time. One that feels far away. Early January 2020.
Travelers were gearing up for another booming year of adventures -- from visits to Japan for the Olympics to cruises galore. But while we aimed for another year of far-flung trips, environmental activists continued their warnings about a growing climate catastrophe and the role travelers were playing.
Some people had been heeding their calls and trying to plan more sustainable trips. Tips on going green from CNN Travel and other sites were popular reading then.
But for the most part, travel projections were for more of the same. We couldn't let problems such as emissions and overtourism keep us at home -- we had a world to see in 2020!
Meanwhile, a new and different kind of threat -- one that couldn't be so easily swept aside -- was about to be unleashed. Reports were coming out about a new, mysterious virus in the interior of China. It wasn't SARS. It had infected dozens of people. But what was it?
We had no idea that our world and the travel industry with it were about to be turned upside down.
A disquieting quiet
Almost in the blink of an eye, everything changed because of that new virus. It swept the globe.
Countries closed their borders. The Summer Olympics were postponed. Cruise ships desperately searched for harbors to let passengers off. Airports were nearly empty. Beach resorts were deserted. Amusement parks became ghost towns. Covid-19 and coronavirus soon became household words.
Then, we noticed something rather nice -- a silver lining of sorts -- during the spring shutdown.
In normally polluted cities such as Los Angeles, skies were clearer. So was water -- people could see marine life in Venice's normally turgid, busy canals. To our delight, birdsong became easier to hear.
There seemed to be a cause and effect at work. And it raised a lot of questions.
Did the sudden drop in global travel really have an unexpected benefit for the environment? Are there ways to keep the perceived benefits going if or when the virus is under control? And perhaps most importantly, can we return to roaming the world one day but be better stewards of our planet while doing so?
As with everything else involving the pandemic, the answers are hard and complicated.
Emissions and carbon footprints
One statistic -- a seemingly small number -- had big things to say about tourism and its effect on the environment before the pandemic: 8%.
That's how much tourism contributed to global greenhouse gas emissions, according to a groundbreaking study from researchers at the University of Sydney and the University of Queensland Australia in May 2018. (Greenhouse gas emissions trap heat in the atmosphere and cause the planet to warm quickly.)
That was some four times higher than previously estimated. And the majority of this carbon footprint (the total amount of greenhouse gases we generate with our actions) came from high-income countries.
The study also found the fast rise in tourism demand was "effectively outstripping" the technological improvements the industry was making toward reducing its carbon footprint. The study didn't have a sunny outlook going forward, either.
"We project that, due to its high carbon intensity and continuing growth, tourism will constitute a growing part of the world's greenhouse gas emissions."
Everything goes out the window
No one knew in 2018 that we'd have a history-making coronavirus pandemic in 2020. That threw everything out the window about where we thought we'd be.
The quarantines and shutdowns caused unprecedented slowdowns in the air transport and tourism industries, according to a July 2020 study from the University of Sydney. It found that overall global emissions dropped by 4.6%. That happens to be the largest drop in history.
But while the environment got a break, the world's economy got slammed. Transport and tourism have been the worst-hit sectors, the study found.
Arunima Malik of the University of Sydney's School of Business and Physics and one of the authors of the study, put it this way in the study: "We are experiencing the worst economic shock since the Great Depression, while at the same time we have experienced the greatest drop in greenhouse gas emissions since the burning of fossil fuels began."
Small countries hit hard
Ya-Yen Sun, senior lecturer at the University of Queensland Australia's School of Business and another author on the studies, told CNN Travel that countries heavily reliant on tourism have been devastated.
"We know tourism is one of the largest [economic] sectors in the world. It contributes about 10% of the global GDP and one in 10 jobs are related to tourism," Sun said.
Smaller nations that don't have diversified economies have taken the hardest hits. Sun said tourism counts for more than half of national GDP in places such as Macau, Aruba and the Maldives.
Sun also pointed out a lot of tourism jobs are offered to women, youths and low-income people. When the world suddenly stopped traveling, "those disadvantaged people then lost their jobs, lost their income. ... We are very concerned about these patterns."
And all of this puts us -- seemingly -- on the horns of a dilemma where either tourism and jobs or the environment and our health come out on the losing side.
As Malik noted in the study, previous financial shocks showed that without structural change, the environmental gains we're seeing now are unlikely to be sustained during a recovery.
'You don't have any simple answers'
Is there any hope at all? Can the tourism industry and economies bounce back but keep the environmental impact lower?
"The problem, of course, is you don't have any simple answers," said Jennie Germann Molz, professor of sociology and anthropology at the College of the Holy Cross in Worchester, Massachusetts. "A lot of tourism destinations have given over such a large part of their economy to the tourism infrastructure that they are dependent on it."
But can we revive tourism in a cleaner way? Take the airlines, for example. Technology innovations are being made to reduce the industry's environmental impact.
Scientists at the Massachusetts Institute of Technology are studying ways to modify nitrogen oxides emissions, which they say is the worse culprit. A study from Imperial College London is looking at how changing airplanes' altitude could help eradicate contrails. And Delta Air Lines plans to become carbon neutral over the next decade by buying offsets and investing in tree-planting programs.
But Sun told CNN Travel these efforts so far haven't been able to offset voracious demand, at least before the pandemic.
"We always thought that technology could offset certain levels of our consumption, [but] basically, technology does not really help much," Sun said. "Even though the aircrafts are becoming more energy efficient, they have to run more frequently."
Try a train
Peter Miller, a scientist at the Natural Resources Defense Council, said flying is one of the worst ways to travel from a carbon emissions standpoint.
"If you're going between DC and New York, and you have the option for how to travel, flying that short-haul flight is the worst of the three options," he said in a CNN Business article. "Driving is not as bad, especially if you have a fuel-efficient car. The train will generally be the best."
But why the focus on aviation when it accounts for only 2% of global greenhouse gas emissions? Sun's reply: "I think what's important is the annual growth rate, which is now 5%."
"People tend to travel more frequently. And the other thing we identify is that people tend to travel to a distant destination. They want to travel further. You have to rely on aviation, which is the elephant in the room," she said.
Malik added, "There is no easy solution to this. And any strategy that we implement, I would think we need to take into account the economic, social and also the environmental side of things. But again, there's no silver bullet."
The cruise industry
Pre-pandemic, more and more eyes were also looking toward the growing cruise industry and its effects on the environment.
Just one example: A report released in 2019 from the sustainable travel group Transport & Environment said the big ships had an oversized environmental effect compared with cars.
It said that over the course of 2017, Carnival Corporation, a cruise operator that encompasses 10 cruise line brands, emitted nearly 10 times more sulfur oxide around European coastlines than all 260 million European cars.
The cruise industry counters it's exploring new technologies to leave less pollution in its wake.
Carnival said in 2020 it was working on reducing emissions by delivering "the second cruise ship in the world to be powered by liquefied natural gas both at sea and in port" as well as in investing in fuel-cell and battery technology.
Norwegian cruise company Hurtigruten said in 2019 it was changing to hybrid cruises as part of a mission to reduce the company's environmental impact.
The Cruise Lines International Association said in 2019 the industry is investing in onboard wastewater treatment plants and high-tech hull coatings and design to reduce water resistance and save fuel. It also committed to having up to 25 ships powered by liquified natural gas in operation by 2030.
Meanwhile, ships in some parts of the world are returning to the business of ferrying passengers, with Covid-19 precautions in place. Environmentalists are sure to keep a close watch on their emissions numbers as they start back up.
Do we just quit flying and cruising?
The short answer from Bruce Poon Tip, founder of small-group travel company G Adventures based in Toronto, Canada: No.
"I think that travel is such a great gift to the world," Poon Tip told CNN Travel. "I think there's better ways in which we can do it for sure ... whether it's carbon capture or whether it's some kind of alternative fossil fuel for flights or electric planes."
Sun offered other ideas.
She noted some governments have offered financial relief to struggling airlines since the pandemic hit. She thinks that could come with promises from the companies "to make good progress in cutting back in carbon emissions."
Sun also emphasizes approaches beyond curtailing emissions at the source.
"The best alternative is not to ask the aviation company to reduce emissions, but rather a consumer-driven strategy which is transferred to other land-based transport," Sun said. "So instead of flying, the best option is to go by bus, go by rail or even your own car."
She also echoed Poon Tip's thoughts about not entirely cutting out flying -- especially to remote destinations -- but making better use of the miles we do fly.
"We can reduce our carbon emissions once arrived at that destination. One good way is to choose one particular destination per trip instead of traveling to multiple places."
More ways to reduce our carbon footprint
Sun pointed out the carbon footprint of food production as well. She said we could consider more vegetarian meals on trips, as meat production is tougher on the environment.
"The other thing we can do is to purchase something that's made locally."
A study published July 10 by Stefan Gössling of Lund University in Sweden and James Higham of University of Otago in New Zealand offered more suggestions -- and an alarm, saying the world has "30 years to decarbonize its economy."
It makes a case for developing domestic tourism markets -- something that Covid-19 has actually sped along. It also notes that the United Kingdom has introduced "significant air passenger duties" and suggests more governments consider carbon taxes, which could help create longer stays.
Overtourism: Too much of a good thing
Where you find emission and pollution problems, you often find the scourge of overtourism.
From dense urban centers such as Amsterdam to isolated historical sites such as Machu Picchu, destinations were struggling with being too popular before the pandemic.
"Tourism scholars have been kind of ringing the alarm bell about the environmental and cultural impact of mass tourism for decades, but in recent years, it has just ratcheted up to the point of what we've been talking about in terms of overtourism," Molz of Holy Cross said.
"So, destinations are pushed beyond their capacity to welcome visitors -- to the point that the reason tourists want to go to these places is kind of lost in the hustle."
In the pandemic, the residents of Amsterdam got their city back. But it came with loss of revenue and pandemic's toll on health and lives.
Can we find the sweet spot?
Along with Venice, Dubrovnik, Bangkok and countless other tourist destinations, Amsterdam is thinking about ways to reach that sweet spot between too few tourists and too many.
"I think it will take a pretty strong political will to do it. Amsterdam is always kind of at the forefront of these innovations," Molz said. "And I think that they are trying to implement policies to encourage local residents back into the city center and the kinds of economies that support local residential life as opposed to tourist life."
Molz also touts other ways to travel -- putting investments in "youth and student exchange programs, which tend to be low impact." She also likes elder hostel or other exchanges "where it's not just city hopping for like weekend getaways."
"Sustainability wise, those kinds of exchanges are low impact," she said. "The longer you can stay in a place ... the more meaningful the experience is for the tourist."
Case study: Dubrovnik
The coastal city of Dubrovnik, Croatia, is called the "Jewel of the Adriatic" and is where some scenes of the TV series "Game of Thrones" was shot. It's also a case study of a city that has grappled with the pros and cons of being a highly prized destination.
Jelka Tepšić, the deputy mayor of Dubrovnik, told CNN Travel how they have been coming to terms with the situation.
Managing cruise ship arrivals has been a key element. In 2019, the city signed a "memorandum of understanding" with the Cruise Lines International Association to better schedule ships coming in and dropping off big groups of travelers all at once.
The pandemic naturally put all of that to a halt. But in "normal times," Tepšić said it's not possible to have more than two cruise ships or 4,000 passengers at the same time in the harbor. And that makes for a better experience for passengers and city residents.
She said the city is also focusing on more domestic and regional travel, hoping to draw in fellow Croatians more as well as neighbors from Montenegro, Bulgaria, Romania, Macedonia and Slovenia. That fits in with the "travel bubble" concept that has arisen during the pandemic, though it remains to be seen how well that concept will work.
The city is trying to ease its reliance on tourism by courting IT companies and more filming, she said. And it's promoting eco-friendly activities beyond its old walls.
"You can walk around easily if you prefer hiking, for example. There are islands in the vicinity and there are some zones which are not still discovered," Tepšić said.
Travel that makes a difference
G Adventures founder Poon Tip yearns to wander -- but on new terms.
"I want people to be carefree again. To travel again. But I don't necessarily think we should be fighting to get back to normal as an industry," Poon Tip said. "I think the travel industry was in a very dangerous place just prior to the pandemic where the destination was no longer relevant."
He saw a situation less about human connections and more about luxury and energy-consuming razzle dazzle.
"People booked travel because of amenities. And so tour operators were in a race to supply more and more amenities for people ... Broadway shows, indoor zip lining, carousels, go kart racing, 10 different restaurants to choose from every night. All these things became so critical, the destination became irrelevant."
Poon Tip said you can travel and help local economies, the working poor and still be a friend to the environment.
For instance, he suggested staying family-run and local hotels versus big chains. And said go out to eat at different places with locally sourced foods instead of just dining on an all-inclusive package.
"We do have an opportunity to rethink, because now that we're forced to start travel slowly again and we have to honor social distancing, we can't just crowd people in overnight. Everything has to be gradual," he said.
"We have the opportunity to say, hang on a second. Venice can be beautiful. We can still have thousands of tourists in Venice, but we can't have hundreds of thousands of tourists in Venice. We have to regulate it somehow."
Poon Tip's got hope for the future. "I'm having conversations with CEOs of cruise ships and airlines who would never have cared that I existed before, but ... those dialogues are happening now. And it's pretty exciting."
Terrible as it's been, the pandemic has brought world tourism to the crossroads of opportunity -- where there is a new chance to take the path that treasures instead of trashes the planet.