The 5% Burning Rule Australia Scrapped and What It Teaches Us

Quick summary

• After its worst bushfire disaster, Australia set a target to burn 5% of public land yearly.

• It dropped that target in 2015, judging blanket area goals a blunt tool for reducing risk.

• Burning near homes protects them; effectiveness varies by place and shrinks sharply in extreme fire weather.

• The lesson for Britain is to concentrate on smarter policy design.

A simple number is a tempting thing in policy. It is easy to set, easy to report against, and easy to defend in front of a committee.

After Australia's worst bushfire disaster, one such number came to dominate the debate about how to manage fire — and the story of what happened to it is worth Britain's attention as our own wildfire risk climbs.

Where the 5% came from

On Black Saturday in February 2009, bushfires in the Australian state of Victoria killed 173 people. The Royal Commission that followed made a raft of recommendations, one of which became famous: the state should aim to burn at least 5% of its public land every year — around 390,000 hectares — as a rolling fuel-reduction target.

The logic was straightforward. Reducing the fuel available to a fire reduces how fast and how fiercely it can spread. Set a big annual burning target, the thinking went, and you steadily lower the risk across the landscape.

Why they dropped it

By 2015, Victoria had abandoned the hectare target. It replaced it with a "risk-based" approach, measuring success not by how much land was burnt but by how much the modelled risk to people and property was reduced — a metric it called residual risk, with a goal of cutting statewide risk to 70% or less of its untreated maximum.

The reason for the switch matters more than the switch itself. Peer-reviewed analysis had shown that a blanket area target is a blunt instrument.

The most reliable way to protect a house is to reduce fuel close to it: a large modelling study of the Black Saturday losses (Gibbons and colleagues, 2012) found that treating fuels near homes offered far more protection than treatment further away.

A percentage target, by contrast, can be met most cheaply by burning large, remote areas that do little to protect anyone — hitting the number without moving the risk.

The wider evidence on how much burning "buys" is mixed. Researchers describe the trade-off as leverage: how much wildfire area you avoid for each hectare you treat. A landmark study of 50 years of burning in south-west Australian forests found real, useful leverage there (Boer and colleagues, 2009).

But when researchers compared many landscapes, they found leverage was often much lower, and in some places close to absent (Price and colleagues, 2015).

In the Sydney region, for instance, it took around three hectares of prescribed burning to reduce the area burnt by wildfire by one. Fuel management helps, but how much it helps depends heavily on where it is done.

Two honest complications

The switch to risk-based measurement is far from a tidy success story.

First, a risk-based target is only as good as what is done under it. Measuring risk more cleverly does not reduce risk unless enough of the right work still happens on the ground; the metric can improve while the outcome does not.

Second, and more sobering, effectiveness falls away when conditions turn extreme. Modelling of the 2019–2020 "Black Summer" fires found that under those conditions the residual risk of area burnt and house loss roughly doubled regardless of how much prescribed burning had been done — and only very high treatment rates, well above anything achieved historically, made much difference at all.

Fuel management can moderate fire behaviour and aid suppression on an ordinary bad day. On the worst days, its protection shrinks.

What applies to Britain

Australian numbers can't be lifted straight onto a British hillside. These findings come from eucalypt forest, unlike Britain's rain-fed blanket bog. The nearest parallel is dry upland heath, not deep peat — where rewetting and restoration lead, with cutting, grazing and firebreaks alongside.

What does apply is the policy design lesson. Australia's experience is a warning against governing fuel management by a single, satisfying number in either direction — whether an arbitrary target to burn more or a blanket assumption that less is always safer.

The defensible approach measures the risk in a particular place, targets the work where it protects most, and is honest that no amount of it removes the danger in the worst weather.

Key Takeaway

Australia set a headline target to burn 5% of public land a year, then dropped it because area targets are a blunt tool — burning in the wrong places to hit a number does little to protect homes.

The transferable lesson for Britain is about how you design and measure fuel-management policy, rather than copying Australia's burning or its figures, which come from forests unlike UK peat.

Why this matters

As Britain builds its own approach to rising wildfire risk, the clearest lesson from Australia is to measure and target fuel management by the risk in each place instead of a single headline number that can flatter the paperwork while leaving people no safer.