Climate Change’s Threat to the Glorious Redwood, Both Here and Afar

The Australia Letter is a weekly newsletter from our Australia bureau. Sign up to get it by email. This week’s issue is written by Meghan Dansie, a freelance reporter in Melbourne.

Framed by native eucalyptuses and ferns in a shady glade near Victoria’s famed Great Ocean Road, a group of Californian giants rises into the Australian sun.

In 1936, Victorian foresters planted a group of California redwoods — the tallest living species on Earth — to gauge their viability for the commercial logging industry. They grew too slowly to be sustainable logging fodder, so they were left alone to drink in the adjacent Aire River and grow ever taller in the cooler climate of the Otway Ranges National Park.

But as the last week of catastrophic flooding in New South Wales and Queensland has shown, environmental stability in Australia is no longer something to rely on.

The lives, wildlife and homes lost in the flooding render a clear picture of exacerbated climatic cycles. This time La Niña, last time El Niño. Footage contrasting this year’s floods with the 2019-20 Black Summer bush fires paints a devastating picture of an Australia already living with the extremes of climate change.

Visiting a towering forest of redwoods, you get a sense of strength and survival in the face of change. They can live for hundreds and even thousands of years in the right environmental conditions, which allow them to survive hot summers, cold winters, wet and dry spells.

Stefan Arndt, a researcher at the School of Ecosystem and Forest Sciences at the University of Melbourne, said that trees like the California redwoods have evolved in a “very specific climate on the Californian coast.” They grow well in cool, humid conditions such as those found in the Otway Ranges, where they take up moisture directly from fog into their leaves.

Professor Arndt said that while the redwoods could cope with occasional heat waves and controlled “cool burns” by tapping into underground water sources, the increased fire risks of climate change posed an “existential threat.”

This week, the Intergovernmental Panel on Climate Change released its sixth report on the current and future effects of climate change. The 2,600-page report, seven years in the making, dedicates a whole chapter to the severe effects of climate change in Australasia. It shows that the Earth is currently heading for warming of over 2 degrees Celsius, largely driven by governments’ slow divestment from fossil fuels.

The week before, a United Nations report estimated that the global risk of highly devastating wildfires could increase by up to 57 percent by the end of the century. It predicts that extreme fires will increase in frequency and spread, even in areas previously unaffected by wildfires.

So what does this mean for the future of iconic tree species such as the redwood?

When wildfire swept through California’s oldest state park in 2020, the old-growth redwoods, among the oldest living trees on Earth, emerged largely unscathed.

However, Professor Arndt said that as wildfires become more frequent and more severe, this is less likely to remain the case, with the secondary effects of hotter, drier conditions also weakening the trees’ ability to bounce back from a fire.

Andrew McKinnon, Parks Victoria’s chief ranger for the Colac Otway region, said that the region had not been exposed to a large fire since the Ash Wednesday fires of 1983, which killed 75 people.

But Mr. McKinnon said that a catastrophic fire in the Otway region that exposes the redwood stand “is not a matter of if, but when,” as more frequent natural disasters result from more severe climatic cycles.

For now, the California redwoods grow healthy and tall in their Australian home, competing for canopy space with the tallest flowering species in the world, the Australian mountain ash. Mr. McKinnon said he believed that growing tree populations outside their native environment could act as a safeguard.

“Diversity needs to be maintained, ideally in its natural habitat, but if that natural habitat is being compromised, then I think it’s imperative that we save that species,” he said.

However, both Professor Arndt and Mr. McKinnon agree that safeguarding survival is no replacement for making every possible effort to tackle climate change now, while it is still possible.

For the thousands of Australians currently affected by “never-before-seen” flooding, the recent international reports simply formalize a reality already being lived.

Now for this week’s stories: