For months, Australians have watched the Iran war through one familiar number.

The price of oil.

When Brent crude rises, concern increases about petrol prices.

When it falls, there is an expectation that relief will eventually reach Australian motorists.

But the latest assessment of global energy markets suggests Australia should start watching something else.

Diesel and jet fuel.

The International Energy Agency's August Oil Market Report shows that the disruption caused by the Middle East conflict is increasingly affecting the refined petroleum products upon which modern economies actually depend.

That distinction is enormously important for Australia.

Cars can run on petrol.

But Australia's freight system runs overwhelmingly on diesel.

Farms depend on diesel.

Mining depends heavily on diesel.

Construction machinery consumes it.

Regional businesses depend on it.

And an island nation sitting thousands of kilometres from many of its international tourism and trading partners depends heavily on jet fuel.

The next stage of the Iran energy crisis may therefore be considerably broader than another increase on the petrol-station sign.

The world's oil cushion is being consumed

The global energy system initially proved surprisingly resilient following the enormous disruption caused by the Iran conflict.

Alternative supplies emerged.

Inventories were drawn down.

Governments released or made emergency stocks available.

Trade routes adjusted.

Consumers reduced demand.

The system absorbed an extraordinary shock.

But those buffers are not unlimited.

The IEA says observed global oil inventories have fallen by approximately 410 million barrels since the war began, taking stocks below 7.9 billion barrels.

Meanwhile, Middle Eastern production remained around 8.3 million barrels per day below pre-war levels in July.

The IEA now forecasts global oil supply will decline by approximately 4.3 million barrels per day on average during 2026, producing a projected supply deficit despite weaker demand.

That changes the calculation.

The world has survived the first part of the shock partly by drawing upon its reserves and flexibility.

The longer the disruption continues, the smaller that safety margin becomes.

This is no longer simply about crude oil

There is an important difference between crude oil and the fuel Australians actually purchase.

Crude oil has to be refined.

Refineries turn it into petrol, diesel, aviation fuel and other petroleum products.

A country can therefore theoretically have access to crude while experiencing shortages or elevated prices for particular refined products.

The IEA's latest figures indicate increasing pressure in those downstream markets.

Diesel exports from Russia, the Middle East and Asia have fallen by approximately 20 per cent of global seaborne diesel trade.

Jet-fuel exports from those regions are down by approximately 34 per cent of global seaborne trade.

Refining margins have risen sharply as supplies tighten.

For Australia, those numbers deserve attention.

Australia imports most of the refined petroleum it consumes

Australia is one of the world's great energy exporters.

That can create a misleading impression of petroleum independence.

The reality is very different.

Australian Government energy statistics show that 79 per cent of Australia's refined petroleum consumption is supplied by imports.

Even Australia's remaining domestic refineries import just under two-thirds of their feedstock.

And 99 per cent of Australia's energy imports by energy content are refined petroleum products and crude oil.

Australia therefore remains deeply connected to international petroleum markets.

We export enormous quantities of coal and gas while importing much of the petrol, diesel and aviation fuel required to keep the domestic economy operating.

The Iran war has exposed that contradiction with unusual clarity.

Diesel is the bloodstream of the Australian economy

Petrol attracts public attention because millions of Australians buy it personally.

Diesel deserves at least as much economic attention.

Consider what depends upon it.

Road freight.

Agriculture.

Mining.

Construction.

Emergency services.

Tradespeople.

Regional transport.

Heavy equipment.

Generators.

Commercial vehicles.

A shortage or sustained increase in the cost of diesel does not simply affect people who own diesel vehicles.

It affects almost everybody.

Every supermarket depends upon diesel

Consider an ordinary supermarket.

Most of the products on its shelves have travelled by road at some stage.

Fruit and vegetables leave farms.

Meat travels to processors and distribution centres.

Packaged products travel from factories.

Imported goods leave ports.

Products are consolidated in warehouses.

Trucks then deliver them to supermarkets.

Those trucks require fuel.

If diesel becomes structurally more expensive, freight operators eventually have to recover the cost.

The supermarket receives products at a higher delivered price.

Some increases can be absorbed.

Others eventually reach consumers.

That is how a diesel crisis becomes a grocery-price problem.

Farmers can be hit several times

Agriculture is particularly exposed.

Farmers purchase diesel directly.

Contractors purchase diesel.

Trucks carrying agricultural inputs use diesel.

Trucks carrying produce away from farms use diesel.

Mining and manufacturing operations producing agricultural inputs also consume energy.

The farmer can therefore experience the same international fuel shock repeatedly through different parts of the business.

And farmers often cannot simply increase their selling price to compensate.

Commodity markets determine many agricultural prices.

That makes rising diesel costs particularly damaging when commodity prices are not rising with them.

Mining cannot simply switch fuels overnight

Mining is another major consideration.

Australia's mining industry operates enormous mobile equipment fleets.

Haul trucks, excavators, loaders and other machinery consume substantial quantities of fuel.

Mines can improve efficiency.

Some operations are electrifying equipment.

Technology will continue changing the industry.

But the existing mining economy cannot simply stop using diesel because international supply becomes expensive.

Higher diesel costs therefore affect one of Australia's most important export industries.

Construction faces another cost pressure

Australia is trying to build more homes.

At the same time, the construction industry has been dealing with elevated labour, materials, insurance and financing costs.

Expensive diesel adds another layer.

Excavators consume fuel.

Loaders consume fuel.

Trucks deliver concrete, timber, steel, windows, roofing and countless other materials.

Tradespeople travel between jobs.

Waste has to be removed.

The fuel component may be relatively small at each individual stage.

Accumulated across an entire project, it matters.

Australia hardly needs another reason for construction to become more expensive.

Then there is jet fuel

The IEA's jet-fuel numbers potentially matter even more strategically.

Australia is an island nation.

International aviation is not an optional part of the economy.

Tourists arrive by aircraft.

Australians travel overseas by aircraft.

High-value and time-sensitive freight travels by air.

Business depends upon aviation.

Regional Australia depends upon aviation.

And aircraft remain overwhelmingly dependent upon liquid aviation fuel.

There is no commercially available battery technology about to replace the fuel requirements of long-haul international aircraft.

For the foreseeable future, aviation requires jet fuel.

A 34 per cent disruption deserves attention

A reduction equivalent to around 34 per cent of global seaborne jet-fuel trade from Russia, the Middle East and Asia does not mean Australia will lose 34 per cent of its aviation fuel.

Global markets reorganise.

Alternative suppliers emerge.

Prices change.

Cargoes are redirected.

Demand responds.

But a disruption of that magnitude changes market economics.

Buyers compete for available product.

Shipping distances can increase.

Refining margins rise.

Supply security becomes more valuable.

That can eventually affect the price airlines pay for fuel.

Airlines have several choices — none are painless

An airline confronted with sustained higher fuel costs can respond in several ways.

It can absorb the cost.

It can hedge fuel prices.

It can improve operating efficiency.

It can alter capacity.

It can increase fares.

Usually the eventual response involves some combination of these.

But airlines cannot permanently buy more expensive fuel without somebody ultimately carrying the cost.

Shareholders can absorb lower profits.

Passengers can pay higher fares.

Routes can become less economical.

The economic consequence has to appear somewhere.

Regional aviation may be particularly sensitive

This matters beyond flights between Sydney and Melbourne.

Regional aviation often operates with smaller passenger volumes and fewer daily services.

Some communities depend upon aircraft for business, healthcare, government services, tourism and family connections.

Higher aviation-fuel costs can therefore become a regional economic issue.

A marginal route can become more difficult to operate profitably.

An expensive airfare can discourage tourism.

Businesses can face higher travel costs.

Once again, the energy shock moves far beyond the petroleum industry.

Tourism should be watching closely

Australia's tourism industry has another reason to care.

International visitors already face the considerable cost of reaching Australia from Europe, North America and parts of Asia.

If international airfares rise because of sustained aviation-fuel pressure, Australia becomes a more expensive destination.

Some travellers will still come.

Others may choose somewhere closer.

Those who do come may compensate for a more expensive airfare by spending less after arrival.

Perhaps they stay fewer nights.

Choose cheaper accommodation.

Eat out less frequently.

Reduce discretionary purchases.

An aviation-fuel shock can therefore eventually reach a restaurant in Cairns, a hotel in Sydney, a tourism operator in the Whitsundays or a retailer in Byron Bay.

Brent at US$90 does not tell the entire story

This is why concentrating solely on crude oil can become misleading.

Brent settled around US$88.88 a barrel on Wednesday.

That is elevated but considerably below some of the extreme prices experienced earlier during the conflict.

A casual observer might conclude that the energy crisis is therefore easing.

But crude is only one component.

If refinery capacity is constrained, particular products are scarce and shipping routes remain disrupted, diesel and jet-fuel prices can remain under pressure even without Brent returning to its previous peaks.

Australians should therefore distinguish between the price of oil and the price and availability of usable fuel.

Hormuz still has not returned to normal

The underlying geopolitical problem also remains unresolved.

The Strait of Hormuz has not returned to anything resembling its pre-war role in global energy trade.

Negotiations continue.

Shipping remains severely disrupted.

Attacks around important Middle Eastern maritime corridors have added another layer of risk.

Until reliable commercial shipping resumes at scale, international fuel markets have to incorporate that uncertainty.

Insurance costs matter.

Tanker availability matters.

Shipping time matters.

Security matters.

All eventually become part of the delivered cost of energy.

Australia is already operating under heightened fuel-security arrangements

The Australian Government has recognised the seriousness of the situation.

Australia is currently at Level 2 — “Keep Australia moving” — under the National Fuel Security Plan.

The government has also announced a broader fuel-security response, including a $3.2 billion Australian Fuel Security Reserve, measures intended to increase diesel and jet-fuel reserves to 50 days, support for Australia's two remaining refineries, and feasibility work examining expanded domestic refining capacity.

That tells Australians something important.

Fuel security is no longer an abstract strategic discussion.

Government is already responding to it.

Stockholding requirements have also been adjusted

The government temporarily reduced Minimum Stockholding Obligations for petrol and diesel, with that reduction extended until 30 September 2026.

Such measures are designed to give the fuel industry greater flexibility during extraordinary disruption.

But flexibility does not create new global fuel.

Ultimately Australia still requires reliable physical supply.

The question is how long the buffer lasts

Strategic stocks are extremely valuable during disruption.

That is their purpose.

But they are a bridge.

They are not an oil field or refinery producing indefinitely.

The IEA's warning about falling global inventories is therefore significant.

The world has been using the cushion built before the conflict to compensate for what has been lost during it.

A cushion becomes less reassuring every time it is drawn down without being replenished.

That makes duration increasingly important.

This could become another inflation problem

The economic danger for Australia remains inflation.

Diesel feeds directly into freight and production costs.

Jet fuel affects aviation.

Higher freight costs affect goods.

Higher aviation costs affect travel and tourism.

Businesses eventually attempt to recover those increases.

That is how an energy-market disruption becomes a broader price problem.

The Reserve Bank cannot manufacture diesel.

It cannot refine jet fuel.

It cannot reopen Hormuz.

But if fuel-related costs spread through Australian prices and inflation expectations, monetary policy cannot simply ignore the result.

Australians can pay twice again

The mechanism is becoming familiar.

First Australians pay through higher fuel-related costs.

Then, if those costs contribute to persistent inflation, households and businesses can potentially pay again through interest rates remaining higher than they otherwise would.

That is why the refined-fuel story deserves considerably more attention than another daily movement in Brent.

Diesel and jet fuel connect international energy markets directly with the real Australian economy.

The world has adapted remarkably well

There is another side to the story.

The global energy system has demonstrated substantial resilience.

Suppliers have adjusted.

Trade has been redirected.

Demand has responded.

Governments have intervened.

The catastrophic shortages feared during the earliest stages of the Iran conflict have generally been avoided.

That should not be understated.

But successful adaptation has a cost.

Inventories have been consumed.

Shipping routes have changed.

Refining margins have increased.

Governments have committed billions of dollars.

Consumers and businesses have paid higher prices.

The system working does not mean the disruption has been free.

Australia's next test may not look like the first

The first phase of the Iran fuel crisis was obvious.

Petrol prices surged.

Motorists noticed immediately.

Government reduced fuel excise.

The political response was immediate because the cost was visible on service-station signs around the country.

The next phase could be subtler.

A freight surcharge.

A more expensive airline ticket.

Higher farm costs.

A construction quote.

A regional delivery charge.

A supermarket price increase.

Individually, none looks like an Iran-war story.

Collectively, they can all originate partly from the same global energy disruption.

The Times View

Australia should stop thinking about the Iran energy crisis solely in terms of the international crude-oil price.

The latest IEA assessment shows why.

The world's inventory cushion is being depleted.

Middle Eastern production remains severely constrained.

Diesel and jet-fuel trade has been substantially disrupted.

And Australia imports the majority of the refined petroleum products it consumes.

That creates a different stage of the crisis.

Petrol remains important.

But diesel moves Australia's freight, farms, mines and construction equipment.

Jet fuel connects Australia with the world and many regional communities with the rest of Australia.

Those fuels are not peripheral to the economy.

They are part of its operating infrastructure.

Australia has already begun strengthening its fuel-security arrangements, including plans for larger diesel and jet-fuel reserves.

The latest international figures explain why.

The next Iran energy shock may not announce itself with another spectacular surge in crude oil.

It may arrive quietly — in the cost of the truck delivering our food and the aircraft carrying us across Australia and the world.

And ultimately, Australians will still pay the bill.