[1] The outbreak in the Rocky Mountain National Park in Colorado began in 1996 and has caused the destruction of millions of acres/hectares of ponderosa and lodgepole pine trees.

However, unusually hot, dry summers and mild winters in 2004–2007 throughout the United States and Canada, along with forests filled with mature lodgepole pine, led to an unprecedented epidemic.

At high elevations, where summers are typically cooler, life cycles may vary from one to two years Female beetles initiate attacks.

On the tree exterior, this results in popcorn-shaped masses of resin, called "pitch tubes", where the beetles have entered.

Warm summers and mild winters play a role in both insect survival and the continuation and intensification of an outbreak.

Adverse weather conditions (such as winter lows of -40°) can reduce the beetle populations and slow the spread, but the insects can recover quickly and resume their attack on otherwise healthy forests.

The infestation, which (by November 2008) has killed about half of the province's lodgepole pines (33 million acres or 135,000 km2)[17][18] is an order of magnitude larger than any previously recorded outbreak.

The United States forest service predicts that between 2011 and 2013 virtually all 5 million acres (20,000 km2) of Colorado's lodgepole pine trees over five inches (127 mm) in diameter will be lost.

Due to temperature changes and wind patterns, the pine beetle has now spread through the Continental Divide of the Rockies and has invaded the fragile boreal forests of Alberta.

One milliliter chitosan per 10 gallons water was applied to the ground area within the drip ring of loblolly pine trees.

[29] The outbreak of mountain pine beetles in the early 2010s, ten times larger than previous outbreaks,[30] created dead pine stands representing a potential fire hazard, prompting the BC government to direct fuel management activities in beetle areas as recommended in the 2003 Firestorm Provincial Review.

The combination of warmer weather, attack by beetles, and mismanagement during past years has led to a substantial increase in the severity of forest fires in Montana.

They concluded by 2020, the pine beetle outbreak will have released 270 megatonnes of carbon dioxide into the atmosphere from Canadian forests.

According to a 2016 study from the Pacific Institute for Climate Solutions rising levels of carbon dioxide may cancel out the pine beetle impact in British Columbia by 2020.

[39] Hydrologists from the University of Colorado have investigated the impacts of beetle-infested forests on the water cycle, in particular, snow accumulation and melt.

They concluded that dead forests will accumulate more snowpack as a result of thinner tree canopies and decreased snow sublimation.

These thinned canopies also cause faster snowmelt by allowing more sunlight through to the forest floor and lowering the snowpack albedo, as a result of needle litter on the snow surface.

The celebration began as an artistic response to environmental change caused by mountain pine beetle infestations in the Black Hills.