Fire!

It's the worst summer for forest fires that many Americans can remember. As you read this, an area the size of Oxfordshire is ablaze, and an effort of military proportions has been launched to stem the flames. But what is it like for those who are really feeling the heat?

It's a strange sensation, driving straight through the middle of a forest fire. Imagine sluicing between thick walls of blood-red flame along a narrow mountain road, like some absurd car advert from the 1980s. Entirely surreal. I do my best not to hum the theme song from Top Gun.

It's a strange sensation, driving straight through the middle of a forest fire. Imagine sluicing between thick walls of blood-red flame along a narrow mountain road, like some absurd car advert from the 1980s. Entirely surreal. I do my best not to hum the theme song from Top Gun.

More than 60,000 acres of the Sequoia National Forest in California are burning up before my very eyes. The heat from the flames radiates straight through the car window and makes my cheeks glow. The sky is a swirl of grey and black. Close to the road, the forest is thick with flames and the blackened trunks of pinon pines too scarred to burn any further. Up on the hillsides, where the fire has already done its worst, the ash deposits layering the forest floor and the residual smoke curling up from the tree stumps look like a ghastly parody of an idyllic snowscape by Caspar David Friedrich.

I had expected the whole affair to be noisier, but with windows closed and the air conditioning whirring, there is nothing to be heard but the hesitant crackle of the car radio as it struggles to find a signal.

For several miles, there isn't another vehicle to be seen on the road. "You'd better take it real slow," the fire marshal at the previous checkpoint had told me.

Now, instead of vehicles, there are rows and rows of firefighters on either side of the road, wearing hard hats and brandishing giant spades and rake-like forks, ready to clear the remaining underbrush and dig firebreaks - in case the flames should jump away from the path to which they had, theoretically at least, restricted it.

The firemen, with their blackened faces, wave at me as I pass, just like those old photographs of GIs awaiting their orders at the front in the Second World War. This is already day five of the largest forest fire in California's history. More than 1,500 people have been drafted in - everyone from helicopter pilots to logistics officers to chefs and tent-builders, as well as the firefighters themselves - and nobody looks like they are going any time soon.

By yesterday, the fire was described as just 15 per cent contained. It will take another eight or nine days at least to "contain" the rest, which is to say keep the fire within a controllable area. The flames themselves probably won't die out until the end of the month.

And the Sequoia National Forest fire is merely the most dramatic of a rash of wildfires afflicting 10 states across a vast swath of the American west and south. About 650,000 acres of forest and brush are on fire as you read this, an area larger than the whole of Oxfordshire - with more going up in flames every day because of freak lightning strikes. It is already the worst fire season in the United States for 12 years, and if the dry conditions that have plagued the west this year persist into the autumn, the chances are that park rangers and forestry rangers will have to dig back a lot further into their records to find anything as bad as this.

Here in California, in the southern Sierra Nevadas about 150 miles north of Los Angeles, the fire-fighting effort has taken on military proportions. The Air Force is flying C-130 air tankers to drop flame retardant. Both military and civilian helicopters are spending their days scooping water out of local streams into giant red bladders and then dropping them on key areas - a hazardous operation because the sheer heat of the fire causes the helicopters to rear upwards without warning.

Because of the variable winds and the treacherous terrain, the fight is proving tough. Having begun in an area known as the Domeland Wilderness, the fire has zigzagged this way and that, jumping at least two firebreaks ("slopping over", as the jargon has it), ravaging a Boy Scout's camp, burning down seven buildings in the small mountaintop village of Kennedy Meadows, and forcing the fire-fighting team to abandon its original base camp at True Meadow for another site near the burned-out buildings. Nobody has been badly hurt, although there have been some cuts and minor burns.

Already, firefighters from 19 different city and county agencies have been called in. And they don't mess about: they are capable of digging mile-long trenches at a moment's notice, or razing an area with chainsaws and spades so that a swath of forest can be reduced to level dirt. Next week, a group of Marines from Texas will join them after undergoing a crash firefighting course. Busloads of farmworkers have also made the perilous journey up the hair-pin road from the Mojave desert floor to work as secondary crews.

They congregate around the base camp, or "staging area", where volunteers tend to medical problems, check on water supplies, prepare packed lunches for firemen too busy to return for a mealbreak (even in this internet age, confronting the fire direct is described as "being on line") and - as though a charbroiled forest were not outdoor cooking enough - make barbecue dinners for several hundred at a time.

The locals who have made their home in this remote mountainscape view the invasion with a mixture of awe and bemusement. "This is what you expect when you live up here," shrugs Ed McFarland, who works at the General Store in Kennedy Meadows. "First day, they issued an evacuation order. Well, there are between 35 and 40 full-time residents up here, but only six of us left. And the firefighters are glad to have us. We know our way around. It saves them a lot of phone time."

The store - built, like everything else around here, out of pine lumber - has become the closest thing to a congregating point in the community. Off-duty firefighters make a beeline for the cigarettes, coffee and soda pop, just about the only commodities that aren't available at base camp. Bearded men in braces and dirty jeans sit drinking light beer and dipping potato crisps into bean dip, waiting for information officers to show up with news updates.

A tongue-in-cheek sign outside the shop declares: "Fire Danger High Today!" A steady stream of people files in to use Kennedy Meadow's only readily accessible telephone, a small luxury that didn't exist at all just nine months ago. "And the reason I moved up here was to get away from the goddamn phone," McFarland jokes.

There is much discussion about the cause of the fire. Since its origin was at a crossroads of wilderness trails, the best guess is that campers either tossed away a lit cigarette, or were what the locals call "toilet paper burners". In other words, they tried to get rid of their used paper by setting light to it. "Not a recommended practice," forestry official Carl Maass says drily.

Such carelessness is becoming an increasing problem as the human habitations encroach ever further on the wilderness of the American West. Forest fires never used to matter so much because they could be regarded as a relatively harmless natural phenomenon so long as life and property were not at stake. Now, however, they are resisted at all costs over increasing areas - resulting in far greater fire prevention but also the risk that when the forest does go up in smoke there will be greater quantities of ground brush, dead logs and other "fuels" lying about to stoke the fire.

Add to that problem the fact that this year has been spectacularly dry - after a relatively wet spell over a couple of summers - and the stage is set for a record-breaking fire season.

The most bewildering fire so far was in May, when a deliberately started and supposedly controlled fire (what the experts call a "prescription burn") ran out of control in New Mexico and ended up sweeping through the town of Los Alamos, home to the National Laboratory where the US government developed the atomic bomb. It seems the "burn" was organised by an inadequately equipped National Park Service (the man responsible has since quit his job), in the absence of many local experts who were away fighting other fires.

Much publicity was given to the singeing the top-secret government laboratories took, and the mysterious disappearance of two hard-drive disks containing nuclear secrets. But the fire also triggered a national debate about the desirability of prescription burns, with environmentalists saying it was more important to let nature take its course than to risk disaster through human intervention (the Los Alamos fire came perilously close to two decommissioned nuclear reactors, which could have turned into mini-Chernobyls).

That argument was bolstered by two prescription fires that went wrong in the past year - one in northern California, one in Colorado. But the forestry experts out in the field point out a simple, uncomfortable truth: that if civilisation is to move into the wilderness, then "letting nature take its course" will inevitably lead to human casualties and property losses.

In the Sequoia National Forest, the rangers believe aggressive human forestry management is the only answer - and by that they mean not only prescription burns but also limited commercial logging, which gets a lot of the fuel timber out of the forest.

"Where there are more people, there's more risk," observes Judy Schutza, one of the Sequoia Forest district rangers. "Prescribed fires are risky, but we need them. Sooner or later the forest will burn, and we'd prefer it happened under our own conditions than Mother Nature's."

Not that controlled fires are much on her mind now: as we speak, news comes in of another "slop-over", near the main road back down the mountain. For more than two hours, there is no safe exit from the fire zone. Then, as the evening gloom mingles in with the smoke, the fire marshals give the all clear. The burning areas I had passed a few hours before are reduced to ash and sand, with a few forlorn tree stumps sticking out. The firefighters are still there, sitting by the roadside, still waving. Their enemy has scurried further up the hill; they are in for another long night.