For the planet, the year without tourists was a curse and a blessing.

With flights canceled, cruise ships mothballed and vacations largely scrapped, carbon emissions plummeted. Wildlife that usually kept a low profile amid a crush of tourists in vacation hot spots suddenly emerged. And a lack of cruise ships in places like Alaska meant that humpback whales could hear each other’s calls without the din of engines.

That’s the good news. On the flip side, the disappearance of travelers wreaked its own strange havoc, not only on those who make their living in the tourism industry, but on wildlife itself, especially in developing countries. Many governments pay for conservation and enforcement through fees associated with tourism. As that revenue dried up, budgets were cut, resulting in increased poaching and illegal fishing in some areas. Illicit logging rose too, presenting a double-whammy for the environment. Because trees absorb and store carbon, cutting them down not only hurt wildlife habitats, but contributed to climate change.

“We have seen many financial hits to the protection of nature,” said Joe Walston, executive vice president of global conservation at the Wildlife Conservation Society. “But even where that hasn’t happened, in a lot of places people haven’t been able to get into the field to do their jobs because of Covid.”

From the rise in rhino poaching in Botswana to the waning of noise pollution in Alaska, the lack of tourism has had a profound effect around the world. The question moving forward is which impacts will remain, and which will vanish, in the recovery.

more than 10 percent, as state and local governments imposed lockdowns and people stayed home, according to a report in January by the Rhodium Group, a research and consulting firm.

The most dramatic results came from the transportation sector, which posted a 14.7 percent decrease. It’s impossible to tease out how much of that drop is from lost tourism versus business travel. And there is every expectation that as the pandemic loosens its grip, tourism will resume — likely with a vengeance.

Still, the pandemic helped push American emissions below 1990 levels for the first time. Globally, carbon dioxide emissions fell 7 percent, or 2.6 billion metric tons, according to new data from international climate researchers. In terms of output, that is about double the annual emissions of Japan.

“It’s a lot and it’s a little,” said Jason Smerdon, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory. “Historically, it’s a lot. It’s the largest single reduction percent-wise over the last 100 years. But when you think about the 7 percent in the context of what we need to do to mitigate climate change, it’s a little.”

United Nations Environment Program cautioned that global greenhouse gases would need to drop 7.6 percent every year between 2020 and 2030. That would keep the world on its trajectory of meeting the temperature goals set under the Paris Agreement, the 2016 accord signed by nearly 200 nations.

“The 7 percent drop last year is on par with what we would need to do year after year,” Dr. Smerdon said. “Of course we wouldn’t want to do it the same way. A global pandemic and locking ourselves in our apartments is not the way to go about this.”

Interestingly, the drop in other types of air pollution during the pandemic muddied the climate picture. Industrial aerosols, made up of soot, sulfates, nitrates and mineral dust, reflect sunlight back into space, thus cooling the planet. While their reduction was good for respiratory health, it had the effect of offsetting some of the climate benefits of cascading carbon emissions.

For the climate activist Bill McKibben, one of the first to sound the alarm about global warming in his 1989 book, “The End of Nature,” the pandemic underscored that the climate crisis won’t be averted one plane ride or gallon of gas at a time.

“We’ve come through this pandemic year when our lives changed more than any of us imagined they ever would,” Mr. McKibben said during a Zoom webinar hosted in February by the nonprofit Green Mountain Club of Vermont.

“Everybody stopped flying; everybody stopped commuting,” he added. “Everybody just stayed at home. And emissions did go down, but they didn’t go down that much, maybe 10 percent with that incredible shift in our lifestyles. It means that most of the damage is located in the guts of our systems and we need to reach in and rip out the coal and gas and oil and stick in the efficiency, conservation and sun and wind.”

herd of Great Orme Kashmiri goats was spotted ambling through empty streets in Llandudno, a coastal town in northern Wales. And hundreds of monkeys — normally fed by tourists — were involved in a disturbing brawl outside of Bangkok, apparently fighting over food scraps.

In meaningful ways, however, the pandemic revealed that wildlife will regroup if given the chance. In Thailand, where tourism plummeted after authorities banned international flights, leatherback turtles laid their eggs on the usually mobbed Phuket Beach. It was the first time nests were seen there in years, as the endangered sea turtles, the largest in the world, prefer to nest in seclusion.

Similarly, in Koh Samui, Thailand’s second largest island, hawksbill turtles took over beaches that in 2018 hosted nearly three million tourists. The hatchlings were documented emerging from their nests and furiously moving their flippers toward the sea.

For Petch Manopawitr, a marine conservation manager of the Wildlife Conservation Society Thailand, the sightings were proof that natural landscapes can recover quickly. “Both Ko Samui and Phuket have been overrun with tourists for so many years,” he said in a phone interview. “Many people had written off the turtles and thought they would not return. After Covid, there is talk about sustainability and how it needs to be embedded in tourism, and not just a niche market but all kinds of tourism.”

In addition to the sea turtles, elephants, leaf monkeys and dugongs (related to manatees) all made cameos in unlikely places in Thailand. “Dugongs are more visible because there is less boat traffic,” Mr. Manopawitr said. “The area that we were surprised to see dugongs was the eastern province of Bangkok. We didn’t know dugongs still existed there.”

He and other conservationists believe that countries in the cross hairs of international tourism need to mitigate the myriad effects on the natural world, from plastic pollution to trampled parks.