A rash of fires has transformed the incredible forest of Siberia from a vast "sink" that absorbs carbon dioxide and releases oxygen into a cause of global warming.
"Suddenly, since 2000, fires have occurred frequently" in the taiga forest in Siberia, said Masami Fukuda, a Hokkaido University professor of snow ice science.
The forest accounts for a fifth of the world's woodland and covers slightly less than 4 billion hectares.