The Northern Hemisphere had a near-record low snow cover in June, especially in western Canada and Alaska, and the drier landscape is likely feeding widespread wildfires this season, scientists said.
Snow cover was low across the Northern Hemisphere. The coverage was 2.1 million square miles, compared to a standard average for the month of 3.63 million square miles, according to data from Rutgers University's Global Snow Lab, which was used in the report.
Western Canada and Alaska had especially low snow cover. Mark Serreze, director of the NSIDC, said that is probably the product of a dry winter and an unusual jet stream that brought on warmer temperatures.
"The way I'm seeing it, the forest fire season you've got right now, it has roots probably going as far back as last winter," Serreze said. "There wasn't much snow on the land and it's been a warm and dry spring and these things all combine."
If the land is dry when lightning strikes, fires are easier to spark, he said.
Alaska wildfires burned over 3.5 million acres as of Thursday, according to the federal-state Alaska Interagency Coordination Center, and is on pace to break the record of 6.59 million acres set in the 2004 wildfire season.
Wildfires are abundant and fierce in British Columbia and other parts of western Canada, pumping out so much smoke that it is visible from space. The fires have choked Vancouver with air pollution that is as bad as Beijing's. In the Northwest Territories, this year's wildfire season is on pace to equal or exceed the record-setting 2014 season, according to the Royal Canadian Mounted Police.
Elsewhere in the far north, in Siberia, this year's wildfires have been deadly. The Siberian Times reported that 33 people were killed in a series of April wildfires and hundreds more were hospitalized; 1,300 homes were lost, according to the Siberian Times and the BBC.
Fires and snow-sparse mountaintops are not the only hallmarks of a drier and warmer era. Arctic ice has been decreasing since satellite records began in 1979, and the NSIDC's June recap is the latest in a long-term downward trend for Arctic sea ice.
Average June sea-ice extent -- the area with at least 15 percent sea-ice coverage -- was the third-lowest since satellite records began, the NSIDC said. Sea-ice extent averaged 4.24 million square miles over the month, about 355,200 square miles below the 1981-2010 average for June, the NSIDC said.
Extent measurements showed what could be seen as a minor recovery from the winter. Earlier this year the ice coverage was hitting record lows during a season when it is usually the most robust; the ice began its annual melt in February, earlier than the usual mid-March melt onset. But the rate of ice loss in June was slower than is usual for the month, the NSIDC said.
Ice loss typically is at its highest rate in July, the year's warmest month, the center said. The minimum extent is reached in September, the end of the melt season.
Inconsistencies this year have made scientists unsure about how to predict sea-ice conditions in the coming months, Serreze said.
"Where will 2015 sit at the end of this melt year? We don't know and the reason is that it depends greatly on the summer weather patterns," he said.
Alaska Dispatch News reporter Yereth Rosen contributed to this report.