CNN  — 

One morning in early October, a now-familiar scene unfolded on a beach in Western Australia.

A shark had attacked a surfer, who was missing. Authorities sent drones into the sky for aerial surveillance, emergency workers jumped onto boats to scour the area, and medics waited on shore.

Days of searching uncovered the man’s surfboard, but his body was never found. He was counted as Australia’s seventh shark attack victim this year – an alarming spike that hasn’t been seen in the country for 86 years.

This year’s attacks have taken place in a number of different states, including Queensland and New South Wales. Among them is a diver who also went missing in January after a suspected great white attack. His body was never found.

To put this year’s spike into perspective, there were no shark attack deaths in Australia in 2019. The years before that only saw one or two deaths annually. The last time the country had seven shark attack deaths a year was 1934, according to a spokesperson from the Taronga Conservation Society Australia. The highest annual figure on record dates back to 1929, with nine deaths.

“In Australia, (this year is) a bit of a blip,” said Culum Brown, a professor at Macquarie University’s Department of Biological Sciences in Sydney. “And in fact the long-term average is one – one fatality per year. So seven is a long way above that, there’s no doubt.”

That average of one death per year has stayed stable for the past 50 years, the Taronga spokesperson said.

It’s not that there has been a sharp increase in shark attacks in Australia overall – there have been 21 shark incidents this year, which is normal and consistent with previous years. The difference is in the fatality rate.

There are a number of possible explanations – several experts have pointed out that year-by-year figures always fluctuate, and this could be simple bad luck. But there’s another possible culprit: the climate crisis.

As oceans heat up, entire ecosystems are being destroyed and forced to adapt. Fish are migrating where they’ve never gone before. Species’ behaviors are changing. And, as the marine world transforms, sharks are following their prey and moving closer to shores popular with humans.

Australia is a hotspot for global warming

On land, Australia’s climate crisis has led to raging bush fires, extreme heatwaves, and one of the worst droughts on record.

But it has also slammed the oceans with acidification and rising temperatures, which can wreak havoc on entire ecosystems. In particular, Australia’s southeast region is on the front lines of the climate crisis – near-surface waters there are warming at about four times the global average.

The Great Barrier Reef, a vital marine ecosystem along the east coast, has experienced such widespread repeated bleaching that more than half the coral on the reef are dead. Massive stretches of mangrove forests have also died in the past decade.

“Those two ecosystems alone are responsible for a massive diversity in marine ecosystems – so you’re seeing huge ecosystems disappearing and/or moving,” Brown said.

This all means that animals are migrating further south than normal in search of a suitable environment. Species like yellowtail kingfish, which are typically seen in northern tropical waters, are appearing in droves near the southern island state of Tasmania. The common Sydney octopus has shifted from the northeastern state of Queensland down to Tasmania. Even plankton and plant life like kelp are moving south.

These types of “marine tropical vagrants” often travel up and down the coastline, Brown said, riding the Eastern Australian Current famously depicted in the movie “Finding Nemo.” But now, climate change means winters are warm enough for these fish to survive the season – so some species are choosing to permanently stay in the southern waters.

“I spend a lot of time in boats off the coast and this year I don’t remember a year where I’ve seen so many bait fish aggregations so close to the coast,” Brown said. Researchers still aren’t exactly sure what drives the movement of many of these species – but Brown added, “there’s no doubt the sharks are just responding to where the bait fish are.”