The image shows an aerial view of the wildfires in Russia's Siberia. Massive forest fires are a common occurrence in the region, but the magnitude of this year's blazes has reached an exceptional level with fears of a long-term effect on the environment.

More than 3.2 million hectares (7.9 million acres) were on fire on Monday alone, mainly in the vast regions of Yakutia in the north and Krasnoyarsk and Irkutsk in Siberia, authorities said. The fires, triggered by dry thunderstorms in temperatures above 30 degrees Celsius (86 degrees Fahrenheit), were spread by strong winds, Russia's federal forestry agency said.

The picture shows a woman taking part in firefighting exercises for volunteers at the Mechta [Dream] forest summer camp outside Moscow. Russian authorities have been slow to declare emergencies and firefighting efforts have been scaled back over economic concerns. The lackluster response has prompted residents to post pleas for help and demands for action online.

The fires could exacerbate climate change, warn experts. Greenpeace says almost 12 million hectares have been burnt this year, causing significant CO2 emissions and reducing the future capacity of forest to absorb the carbon dioxide. Some scientists posted satellite images from NASA showing the clouds of smoke reaching Arctic areas.

The smoke from the wildfires has affected not only small settlements, but also major cities in western Siberia and the Altai region as well as the Urals such as Chelyabinsk and Yekaterinburg, and disrupted air travel. The image shows how the smoke has enveloped the city of Kemerovo in southern Siberia.