Thousands of wildfires engulf broad expanses of Russia each year, destroying forests and shrouding regions in acrid smoke.
Northeastern Siberia has had particularly massive fires this summer amid record-setting heat. Many other regions across the vast country also have battled wildfires.
Some factors behind Russia's endemic wildfires and their consequences:
In recent years, Russia has recorded high temperatures that many scientists regard as a clear result of climate change. The hot weather has caused permafrost to melt and fueled a growing number of fires.
The vast Sakha-Yakutia region of Siberia has had a long spell of extremely hot and dry weather this summer, with temperatures reaching 39 degrees Celsius (102 degrees Fahrenheit) and setting records for several days. The heat wave helped spark hundreds of fires, which so far have scorched more than 1.5 million hectares (3.7 million acres) of land, making it the worst-affected region in Russia.
The fires have shrouded Yakutia's cities, towns and villages in thick smoke, forcing authorities to briefly suspend flights at the regional capital's airport. The Defense Ministry deployed transport planes and helicopters to help douse the flames.
Fedot Tumusov, a member of the Russian parliament who represents the region, called the blazes "unprecedented" in their scope.
The forests that cover huge areas of Russia make monitoring and quickly spotting new fires a daunting task.
In 2007, a federal network to spot fires from aircraft was disbanded and had its assets turned over to regional authorities. The much-criticized change resulted in the program's rapid deterioration.
The government later reversed the move and reestablished the federal agency in charge of monitoring forests from the air. However, its resources remain limited, making it hard to survey the massive forests of Siberia and the Far East.
Neglect of fire safety rules
While some wildfires are sparked by lightning, experts estimate that over 70% of them are caused by people, from carelessly discarding cigarettes to abandoned campfires, but there are other causes.
Authorities regularly conduct controlled burns, setting a fire to clear the way for new vegetation or to deprive unplanned wildfires of fuel. Observers say such intentional burns often are poorly managed and sometimes trigger bigger blazes instead of containing them.
Farmers also use the same technique to burn grass and small trees on agricultural lands. Such burns regularly get out of control.
Activists and experts say that fires are often set deliberately to cover up evidence of illegal lumbering or to create new places for timber harvesting under the false pretext of clearing burned areas.
Activists in Siberia and the Far East allege such arson is driven by strong demand for timber in the colossal Chinese market, and they have called for a total ban on timber exports to China.
Officials have acknowledged the problem and pledged to tighten oversight, but Russia's far-flung territory and regulatory loopholes make it hard to halt the illegal activity.
Critics blame the 2007 forest code that gave control over timberlands to regional authorities and businesses, eroding centralized monitoring, fueling corruption and contributing to illegal tree-cutting practices that help spawn fires.
Russian law allows authorities to let wildfires burn in certain areas if the potential damage is considered not worth the costs of containing them.
Critics have long assailed the provision, arguing it encourages inaction by authorities and slows firefighting efforts so a blaze that could have been extinguished at a relatively small cost is often allowed to burn uncontrolled.
"They eventually have to extinguish it anyway, but the damage and the costs are incomparable," said Mikhail Kreindlin of Greenpeace Russia.
In addition to destroying trees, wildfires also kill wildlife and pose a threat to human health by polluting the air.
Carbon emissions from fires and the destruction of forests, which are a major source of oxygen, also contribute to global warming and its potentially catastrophic impact.
This year's fires in Siberia already have emitted more carbon than those in some previous years, according to Mark Parrington, a senior scientist at the European Centre for Medium-Range Weather Forecasts.
He said the peat fires that are common in Siberia and many other Russian regions are particularly harmful in terms of emissions because peat has been absorbing carbon for tens of thousands of years.
"Then it's releasing all that carbon back into the atmosphere," Parrington said.
While pledging adherence to the Paris agreement on climate change, Russian officials often underline the key role played by their forests in slowing down global warming. However, regular wildfires have the opposite effect, dramatically boosting carbon emissions.
"They emphasize that huge areas are covered by forests but neglect the effect of greenhouse gas emissions resulting from fires," Greenpeace's Kreindlin said.