Anyone in the Cairns tourism industry who might be feeling a sense of panic about the largest destruction of coral on the Great Barrier Reef since divers first strapped on snorkels is not letting it show.

The north-eastern Australian city – a global holiday destination where the natural wonder’s name festoons everything from the signs greeting airport arrivals to the local casino – is celebrating a storming tourist trade over the last 12 months.

Nearly three million people visited in the year ending 31 March, according to Tourism Tropical North Queensland, including an 11% bump in overseas visitors to 830,000 and a 33.5% surge in domestic tourists.

However, chief executive Alex de Waal says this “extraordinary” spike would have been even bigger had it not coincided with global publicity about the deteriorating state of the reef. The reef has been in the media as never before over the past year because the coral is in mortal danger. Bleaching caused by climate change has killed almost 25% this year and many scientists believe it could be too late for the rest.

The publicity surrounding this has unfolded in three waves, each one spawning bitterly contested accounts of Australia’s stewardship of the reef, pitting politicians, scientists, conservationists and even TV show hosts against each other.

First there were the UN deliberations that came down against listing the reef as “in danger” last July, which flagged rather than foreclosed the wider attention. Then there was David Attenborough’s Great Barrier Reef documentary series last December, which was taken in Australia as either a warning about or an endorsement of its care. And then at the close of an Australian summer that seemingly would never end, warm El Niño waters started poaching corals, leading to 93% of its individual reefs showing signs of bleaching – the stark white state that indicates coral is on life support.

The worldwide reporting of this event – at least in terms of its popular reception – is as great a concern to some Cairns tourism operators as the bleaching itself. De Waal says it wasn’t long before it became apparent there was a perception overseas “that 93% of the reef was dead”.

“The fact of the matter is, people in travel agencies around the world are asking the question, ‘Is it still worthwhile going to the Great Barrier Reef because we’ve heard that it’s died?” Try as the Australian government might – with efforts including having the UN drop from a conservation report all mention of the continent out of concerns for how it could affect tourism – public perceptions are hard to manage. One visitor to Cairns, Cyril Mathieu, of Annecy in France, says something that might turn a tourism boss’s face a shade of bleached coral.

Healthy coral photographed near Cairns last year. Photograph: Alamy

“They want to close it to tourists, right?” says Mathieu, 25, who has been out on the reef three times over his 18-month stay in Australia. “I think it was on the internet, maybe it was a rumour. If it’s getting whiter and whiter, maybe it makes sense.”

Mathieu may be thinking of the Maldives, where earlier this month it was reported that the government is considering closing the reefs as coral bleaching has now reached its waters.

The confusion over how much of the Great Barrier Reef is affected has not helped matters, says De Waal. The perception that 93% of the reef is dead, he says, is “absolutely false”. It is in fact 22% of coral on the reef that has died.

But De Waal may be worrying unnecessarily. On a sunny day in Cairns last week there was little evidence the negative message was keeping people away. Canadians Audrey Tremblay, 20, and Patricia Caya, 21, both about to spend three days on a boat on the reef, said they had heard no concerns about its condition back home in Montreal. “We don’t learn about Australia much from the news,” said Caya. Nor are these concerns on the radar at Golden Holidays Travel, one of the operators servicing the booming 225,000-strong Chinese tourist market. It is the “planeload after planeload” of Chinese tour groups in particular that have kept recent trade strong, according to local officers, even during the traditional lull in the wet season.

“There’s no panic here,” says one. “Sometimes we can’t get people on the boats, they’re that full.” UK visitors are also up and will “go through the roof” the more play the Attenborough series gets, he says. One tour operator, Down Under Dive, spent a rumoured $8m late last year on a new catamaran with hydraulic arms that can lower 60 people at a time into the water.

Eighty per cent of the coral death is confined to the more remote top third of the reef, north of Cairns, so little if any of this destruction will be seen by day-trippers off the city’s coast. “What we’re seeing is not really anything out of the ordinary,” says Jeff Cameron-Smith from Reef Magic Cruises – a “medium sized” diving operator that services 60,000 clients a year and employs more than 50 staff, including four marine biologists who run coral surveys. In one example of the coral recovering, he tells of a “stark white anemone with a Nemo, a bright orange clownfish still sitting inside” that was photographed returning to colour after just two weeks at the company’s Moore Reef dive site, just off Cairns.

Despite these positive noises coming from the coastline, however, De Waal says he has no doubt that “without the reef discussions, the [visitor numbers] would have been stronger”. Cameron-Smith acknowledges the “devastation” occurring further to the north and the fact that bleaching is a major concern, adding: “If you had no reef, you’d have no Cairns, you’d have no North Queensland pretty much, as far as tourism goes. The reef is the draw card.” He says he was also disturbed by recent feedback from tourism package wholesalers about the perception in Europe of threats to the reef.

“I actually said to one, ‘How is this perceived – as Australia destroying the reef? Or is this [being seen as] a global warming issue?’

“He said: ‘It’s you guys. It’s Australia because you guys are dumping dredge spoil on reefs, because you’re doing this and that, you’ve got shipping channels going through the reef, your water quality’s not great.’ All of which is totally untrue.”

Dying and dead coral after bleaching at Lizard Island, north of Cooktown, on the Great Barrier Reef. Photograph: the Ocean Agency

Some Cairns operators have reportedly refused to take journalists out on the reef to inspect bleaching for fear of feeding more negative publicity. One group has even refused to take the leaders of the Australian Greens to bleached coral sites during the current federal election campaign, and dismissed their efforts to link the coral damage to climate change and the coal industry.

But operators in a $6bn-a-year reef tourism industry, who are largely yet to test their political voice on Australian climate policy, might still emerge with a different consensus on the issue.

Cameron-Jones says: “I don’t know what as an operator or as an industry we can do about climate change in the short term. It has to be a whole world approach.”

Bleached and dying

Coral bleaches when the water surrounding it is too warm for too long. The situation is made worse if there is limited cloud cover and a high level of UV radiation blasts the coral.

Stressed coral polyps expel the colourful algae living inside them and the transparent coral reveals a white skeleton. As the algae gave the coral 90% of its energy, the coral starves. Unless temperatures quickly return to normal, the coral dies, seaweed takes over.

The first recorded bleaching was in 1911 in the Florida Keys, followed by the Great Barrier Reef in 1929. In 1979 came the first “mass bleaching”. Every year since, bleaching has been reported somewhere; 1998 was the worst yet, 2016 may be more severe.

Since 1998 there have only been three mass bleaching events on the Great Barrier Reef. In 1998 and 2002, 40% of the reefs escaped bleaching. The present event is said to be five times stronger than the previous two.

The latest event began around Hawaii in 2014. In early 2016 it spread to the Great Barrier Reef, where 93% of 3,000 reefs were hit by bleaching. One study linked the bleaching to the rise of global warming in the 1970s.