How the Heat Dome Stole Christmas

I’m not normally concerned about having the perfect home — though I’m also not normally interviewing Mr. Christmas Tree himself from my living room, with a scraggly, disco-lit Nordmann fir in the background of my Zoom shot.

A high-quality tree should have “up-turning branches, so they’re not drooping,” he was telling me. “They have really nice dark green needles” and “what I would consider to be a uniform density, all the way to the top of the tree.” As he talked, my eyes slid to the corner of my computer screen, where I noticed that the topper on my rather limp and gappy specimen was also crooked.

But in the true spirit of the holiday season, Gary Chastagner — a plant pathologist at Washington State University whose extensive research on ornamental holiday conifers has earned him his jolly nickname — was generous. He added that there’s also a robust market for imperfect “Charlie Brown” Christmas trees, to the point that growers will actually avoid culling arboreal oddballs that might attract people like, well, me.

Soon, they may not have much choice. The normally cold and rainy Pacific Northwest is the Christmas tree-growing capital of the U.S., producing more than 5.4 million trees every holiday season, many of which get exported to places like New York, where I procured mine from a sidewalk lot. But back in 2021, a heat dome pushed temperatures in the Northwest to nearly 120 degrees Fahrenheit. The event killed the year’s seedlings and browned new growth on older trees — the consequences of which we’re already seeing in the form of patchy trees and shortages, and will continue to feel for years to come.

Unlike most farmed products, Christmas trees grow slowly; it can take seven to 12 years for a seedling to reach 8 feet tall, depending on the species. To ensure a consistent stock of Christmas trees for the years ahead, most growers plant the same number of seedlings each season with the expectation that there will be some amount of loss along the way.

But the heat dome was exceptional; it “killed off virtually every seedling that was planted on farms in 2021, plus some from the year before,” Sheila McKinnon, a former grower and representative of the Puget Sound Christmas Tree Association, in Washington state, told me over email. One dismayed grower told CNN at the time, “There are literally fields with hundreds of acres of dead seedlings. Just 100% mortality across the entire field.”

The timing couldn’t have been worse. Because the heat dome occurred in early summer, young trees as well as the new shoots and buds on older trees had not yet “hardened,” and were therefore especially vulnerable to the high temperatures. Additionally, prevailing drought conditions in the Pacific Northwest in 2021 limited the available groundwater to rehydrate the superheated plants. “They just shut down because they couldn’t get enough water; they literally just cooked,” Judith Kowalski, a researcher in the Christmas tree program at Oregon State University, explained to me.

Not all trees — or tree farms — were affected equally. Nordmann, Turkish, and some Noble firs mature later in the season than Douglas firs, so their tissues were softer and “just fried,” Kowalski said. Regional differences mattered, too. For example, it didn’t get quite as hot in the southern Willamette Valley in Oregon, and trees there faired a little better. But even microclimates could mean the difference between life and death. “On a hill, where there was a breeze, it made a lot of difference,” Kowalski said. By that same token, so did “a little valley, where trees didn’t get any air circulation.”

Some unlucky growers lost as much as 90% of the year’s seedlings; by one estimate, 70% of the Noble fir seedlings planted in Oregon in 2021 died. McKinnon sounded fatalistic when she described the damage. “There is no way to recover from this loss,” she said. “Some folks tried to buy more seedlings the following year,” but “instantly doubling the supply wasn’t possible.”

Call them the Ghosts of Christmas Yet to Come — because conifers take so long to mature, the effects of the 2021 heat dome will cascade into the future, causing shortages of certain trees at certain heights for a decade or more. If the typical Noble fir takes roughly 10 years to grow 8 feet, for example, then the 2021 heat dome could cause shortages of 9-foot-tall Nobles that won’t be felt until 2032.

The good news is, customers don’t usually shop for a specific species and height of Christmas tree; they just want something that looks good (or, in my case, passable) in their living room. While there might be a 9-foot-tall Noble tree shortage in 2032, customers in the market for a large tree that year will probably switch to buying a Douglas fir or some other variety, instead. Unless a grower depends heavily on one specific type of tree that was widely killed off by the heat dome, the impacts of 2021 can “kind of get absorbed” by the other stock, Kowalski said.

Of course, all that assumes that there is only one bad year.

“The heat dome is part of a pattern that we’re seeing of increased frequency of very high temperatures, much more than normal,” Chastagner told me. “2022 was one of the driest summers on record. We only had half of an inch of precipitation during the summer. And unlike other areas, the growers in the Pacific Northwest generally do not irrigate trees.”

Chastagner’s research indicates that trees in the Pacific Northwest have been so stressed by the region’s dry summers that it’s making them vulnerable to diseases like armillaria, a root rot caused by a fungus, “which we normally didn’t see.” And high temperatures don’t just affect a tree’s growth; warmer autumns also lead to worse needle retention once the tree is cut, meaning more needles on your floor in mid-December. And while one summer of extreme temperatures might lead to shortages that other stock can absorb, that stops being true when there are back-to-back heat domes. As Tom Norby, the president of Oregon Christmas Tree Growers Association, told The Oregonian after the 2021 heat dome, “One year is not a catastrophe. Two years becomes a big problem. Three years, it’s a catastrophe.”

With that in mind, Chastagner and his team at WSU — as well as Kowalski and the researchers at OSU — are exploring everything from introducing irrigation to farms (which is complicated and expensive, but also effective) to determining what conifer varieties will be better suited to a hotter future in the region. Already, the makeup of tree farms in the West is changing: In 2017, native Noble firs made up about 54% of the trees grown in the Pacific Northwest, with Nordmann and Turkish firs (which are native to Turkey and Georgia) only making up about 4%. Now, more and more growers are planting exotic Nordmann and Turkish firs due to their drought tolerance.

But don’t worry: Charlie Brown Christmas trees aren’t going anywhere. Heat or no, there will always be evergreens that require aggressive pruning or otherwise turn out a little bit, well, special. “When I get asked to give talks on what the perfect Christmas tree is,” Chastagner said with — did I only imagine it? — a kindly glance over my shoulder, “I say it’s all in the eye of the beholder.”