Canada is having its worst fire season in modern history. The fires have burnt more than 20 million acres, casting hazardous smoke over parts of the U.S. and stretching Canadian firefighting resources thin. Public officials and news headlines have declared the fires as “unprecedented,” and in the modern-sense they are. But researchers who focus on the history of wildfire in Canada’s boreal forests say the situation is not without precedent. …Canada’s boreal forests have a long history of major wildfires, research shows. In fact, scientists believe the country’s boreal forests burned more in the past than they do today. …Normand Lacour, a fire behavior specialist with Quebec’s fire prevention agency said he’s seen wildfire seasons lengthen by about six weeks since he started his firefighting career 35 years ago — a trend that he expects to continue.