Fires in the Siberian forests - the largest in the world and vital to the planet's health - have increased tenfold in the last 20 years and could again rage out of control this summer, Russian scientists warn.They say they have neither the money nor the equipment to control or extinguish the huge forests fires often started illegally and deliberately in the Russian far east by rogue timber firms who plan to sell cheap lumber to China.
In 2003, one of the hottest summers in Europe, 22m hectares of spruce, larch, fir, Scots pine and oak were destroyed, charred, scorched or in some way affected by fire. On one day in June that year, a US satellite recorded 157 fires across almost 11m hectares, sending a plume of smoke that reached Kyoto 5,000 kilometres (3,107 miles) away.
Forests absorb carbon dioxide from the air and release oxygen. The world's forests are part of the calculations behind the Kyoto agreement, ratified by Russia, Britain and many other nations, but not the US or Australia, to control the greenhouse emissions that fuel global warming.
Forests have also become part of the currency of exchange, called carbon trading, intended to keep economies stable while limiting emissions overall. Most attention has been focused on the steady destruction of the surviving Amazon and Indonesian forests.
But the so-called "boreal" forests of Siberia, slow-growing but huge, are equally vital. They became a global issue in 2003, when so many fires raged in Siberia and the Far East that atmospheric scientists identified their smoke and soot in Seattle, on the far side of the Pacific.
"You should try to protect your forests, because they are the lungs of the planet: they absorb carbon dioxide," said Anatoly Sukhinin, of the Sukachev Institute of Forestry in Krasnoyarsk, the once-closed Siberian centre where the British Council has just opened Zero Carbon City, a touring exhibition on global warming. "It looks to me like these huge forests are currently being devoured by a powerful lung cancer."
Russia's forests stretch almost from the steppes of central Asia to the Arctic permafrost, and from European Russia almost to the Bering Sea. Vast areas are almost pristine, the preserve of migrating birds and the occasional hunter and trapper.
In the north, the trees grow slowly, some reach the age of 400-500 years, and are vulnerable to any disturbance. In the south, the forests become cluttered with dry underbrush, and at risk from electrical storms. But the biggest threats come from climate change and deliberate arson by people intent on illegal logging.
"One factor is global warming, and there is absolutely no doubt that this is happening. Global warming results in more extreme droughts: greater droughts, longer droughts, and more frequent droughts. The other factor is underfunding. We cannot do a good job to preserve and protect our forests," Dr Sukhinin said. "There is very little money to fund such work. We have some equipment left from the old times, we have some organisational support, but we are critically underfunded by the government."
Cooperation with US and Canadian partners means that they get the big picture from US government satellites.
In the enormous expanses of Siberia, they need specialised firefighting aircraft. The government in Moscow has designed and made some, but sells or leases them to other countries. Even when the foresters can identify the areas ablaze, they can do little.
The forests are at risk in early spring - after the dry cold of the Arctic winter - and in high summer, when temperatures soar. Fires in the forests are a threat to oil and gas pipelines, to wildlife and to the permafrost itself. Heat from the blazing underbrush and the parched canopy can disperse the clouds in a fierce thermal updraft, melting the frozen soil and leaving behind a landscape of charred stumps and dripping swamp.
On top of natural hazards, the Russian scientists count the risk of arson.
Paradoxically, forests have become money to burn. Licences to log healthy forest are expensive. But timber merchants and logging companies can buy cheap licences to clear stands of timber in some way damaged by fire.
Forests quickly recover from fires which rage through the underbrush. Many trees have adapted to survive periodic ground-level fire, and flourish on the ashes of their more lowly competitors.
"After a fire, the timber improves and is even better," said Dr Sukhinin. "And that is the time when people can come in, fell the trees, sell the timber to China and get good money.
"The Chinese themselves, they pay well and they pay the same money for timber from affected areas as for timber from unaffected areas - and that is the reason for the arsonists. It's illegal if you don't have a licence."