A few weeks ago, Joe Fontaine stood in the middle of one of Western Australia’s eucalyptus forests, on another hot and dry day, deprived of the usually harsh background noise of bird calls.
“I could hear this scratching sound coming from the trees,” says Fontaine, a forest ecologist at Murdoch University in Perth.
As they loosened the bark, a handful of beetle larvae “about the size of your little finger” ate away the dead and dying wood. “When the trees are stressed, the beetles get the upper hand,” he says.
Above Fontaine the canopy turned brown. Trees that are more than a century old are barely alive. Some of these giant jarrahs may survive, but others will not.
It’s a scene recreated in coastal forests and scrub that stretches for more than 1,000 km (620 miles) in the state’s south-west, following drought and baking heat.
Many of these ecosystems are dominated by eucalyptus trees such as jarrah and marri, and coastal shrublands dotted with banksias, the likes of which are found nowhere else on earth.
Photos of dead and dying shrubs and trees flood Fontaine’s inbox. One of the first signs came in February, when Perth’s street trees began dying after a record number of days above 40 degrees Celsius. The city experienced the driest six months – from October to March – since measurements began.
In 2010 and 2011, similar scenes occurred in the southwestern eucalyptus forests of the state — a die-off event that prompted more than a dozen investigations. Drought-stricken forests were hit by fire years later, releasing carbon dioxide, and raising concerns that the forests could turn into a source of carbon rather than a store.
Dr. Katinka Ruthrof, a senior research scientist at the state government’s Department of Biodiversity, Conservation and Attractions, says the current mortality has similar characteristics to that of 2011. The department is assessing the damage using images from satellites, fixed-wing aircraft and drones , along with field checks.
“Some plants can survive and resprout if conditions improve, but many plants can die,” she says. “This depends on how long the dry season lasts.”
Ruthrof says changes to the structure and composition of habitats for some species would have a flow-on effect, including providing habitat and food sources for wildlife.
Dr. Mark Harvey, curator of spiders, centipedes and millipedes at the Western Australian Museum, says the south-west is home to hundreds of invertebrate species found nowhere else.
“The southwestern corner of Western Australia has been isolated from other parts of the continent for the past three million years. This allowed species to develop in isolation.”
Those species have been accustomed to humid conditions for thousands of years, he says.
“We are quite concerned about this reclamation. If the animals don’t have a coping mechanism, such as digging, to escape the heat, they literally die.
“They are dying out locally. They have nowhere to go. It will take thousands of years to recolonize, even if the habitat becomes good again. The prognosis is not good.”
Fontaine says seeing the death of brush and forests is “disturbing” and he is concerned about wildlife.
“I’m going for leather now to make people say ‘oh shit, we need to document this,’” he says.
Clear climate signal
Fontaine’s colleague at Murdoch University, atmospheric scientist Dr Kerryn Hawke, says the region’s trees and plants are used to a Mediterranean climate with cold fronts from the ocean to the south, which bring good rainfall in winter.
But studies have shown that these fronts are moving further south, away from the coast.
She says: “These fronts don’t reach as far north anymore, and that means we’re seeing less frontal rain showers, and when they do reach us, it’s not as intense. And we are seeing more and more very hot days as a result of climate change. The vegetation is simply not used to so little precipitation.”
Over the past 12 months, much of the west of the state has experienced rainfall that has been well below average and in some places the lowest on record, while temperatures have been among the highest on record.
“It’s a perfect storm of temperature and rainfall. But what was striking was the heat we had very early,” she says, pointing to heat waves in September and November.
The conditions in recent months are part of an apparent drying that scientists have seen in the region since the 1970s.
Compared to the period from 1901 to 1960, cool season rainfall has declined by 20% over the past twenty years. Very wet years have almost completely disappeared.
About half of this change is attributed to rising greenhouse gas emissions, which could be an underestimate, according to a study led by scientists at the Bureau of Meteorology.
Even with rapid reductions in greenhouse gas emissions, the study suggested, the drying trend would likely continue for the rest of this century.
Dr. Michael Grose, a climate scientist at the Australian government’s Commonwealth Scientific and Industrial Research Organisation, says scientists saw a drying trend as early as the 1970s.
“It is one of the clearest and strongest signals of average rainfall anywhere in the world,” he says.
Fire and fear
There appears to be little relief on the horizon, with forecasts for the next three months suggesting more warm and dry weather is on the way.
Fontaine says with so much dead vegetation, the risk of wildfires increases.
Firefighters will have to be careful, he said, as they conduct prescribed fires to reduce the risk of larger, out-of-control fires.
About 430km south-east of Perth is Walpole, where David Edmonds runs a beef and orchid farm while volunteering with the Walpole-Nornalup National Parks Association.
He grew up in Walpole and has seen parts of the bush – including giant 90 meter karri trees – turn brown this year.
“The rain didn’t stop until very early. The dieback is really becoming apparent on the granite outcrops,” he says.
“It’s sad. You worry whether this is a one-off or something that happens more often. We can’t water the trees.”