Climate science on trial

In late May, the Federal Court ruled that the Minister for Environment has a duty of care to shelter future generations from the effects of climate change. The case took into account evidence presented by an independent expert witness, Dr Karl Mallon, who quantified how climate change will impact today’s children.

Mallon’s analysis – which, among other things, found that climate change will cost each young Australian up to $245,000 over their lifetime – was instrumental in Justice Bromberg’s ruling.

The court established that independent expert opinion was necessary to gauge the extent to which climate change would harm Australian children. Mallon was approached to act as the expert based on his work at consultancy firm Climate Risk, which advises governments and businesses around the world about how extreme weather and climate change may affect built assets and communities.

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Fast facts: Sharma v Minister for the Environment

• The case was brought to court by eight teenagers and their litigation representative, 86-year-old nun Sister Marie Brigid Arthur.
• They were attempting to block a proposed extension to Whitehaven’s Vickery mine in northwest NSW by running a negligence case.
• Although the injunction to stop the mine wasn’t granted, the judge ruled that the Minister for Environment has a duty of care to protect future generations from harm.

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“It’s the first time I’ve been an independent expert in a court case, and it was an interesting learning curve,” Mallon says.

What was unexpected, he says, was the difference in communication styles. In science, it’s all about the evidence base – “you’re not believed because of who you are, even if you’re Einstein”.

But in a court case, it’s all about an individual’s opinion.

“You can support your opinion,” Mallon adds. “We just did what we always do, which is provide a supporting report with all of the evidence, all the analysis, all the mathematics – but in the end a lot of it was: ‘You’re the expert, what’s your opinion?’ And that was quite confronting.”

Mallon and his team prepared a report based on a series of questions given to him by the court, revolving around: “What would be the future harm to children in Australia from climate change?’

The team set out to provide answers that were quantifiable.

“I’m a big fan of numbers,” Mallon says. “Rather than saying ‘climate change is going to be bad and it’s going to cause harm’, what we do as a business is to say, ‘well, how much harm? What kind of harm?’”

They decided to focus on financial and physical impacts on young people (aged 0–18 in 2020), based on what they thought the court would understand and consider.

“While the range of possible mechanisms of harm is wide and complex, I have confined my opinion to losses of family wealth in housing, losses of income due to worker productivity and economic impairment, and the health impact of increased heat-stress,” Mallon explains in the report.

Using Climate Risk’s sophisticated software, the team drew on the Intergovernmental Panel on Climate Change’s high-end emission scenario (RCP8.5, the only one consistent with increasing coal production) along with atmospheric modelling.

They calculated, for example, that the average loss to the value of family homes by 2030 will be $41,000–85,000 per child; that rising temperatures will cause productivity dips that will result in a whole-working-life loss of about $75,000; and that approximately 20% of young people today will be hospitalised for heat stress during their senior years.

What’s particularly interesting about the case is that Mallon’s credibility as an independent expert, and therefore his opinion, wasn’t questioned in court. His evidence was accepted wholesale.

Previously, in the eyes of the law, the science was up in the air, but now the Federal Court has said it’s a no-brainer.

Even Greta thinks it’s a great result.