It’s easy to take supply chains for granted. When they work correctly, they’re largely invisible. But supply chains affect our lives profoundly, as we discovered when the COVID-19 pandemic sparked shortages of everything from toilet paper to used cars to microchips. We asked PSU’s Carlos Mena, Nike Professor of Supply Chain Management, to help us understand why some supplies became scarce during the pandemic, focusing on lumber as an example. (Lumber prices climbed 300% above pre-pandemic prices, peaking in May 2021, according to the National Association of Home Builders.) “Like most industries, the lumber industry has suffered significant disruptions to supply and demand,” says Mena. “Many of these disruptions are associated with COVID-19, but not all.”

Supply:

CLIMATE CHANGE:

Higher temperatures make trees more vulnerable to fires and pests.

WILDFIRES:

“It takes years for a tree to grow,” says Mena. “If the forest burns, you cannot just increase supply.”

PESTS:

Bark beetle infestations have destroyed timber across central Europe and are a growing problem in the U.S.

DRIVER SHORTAGES:

Fewer drivers make it difficult and expensive to move the lumber

WORKER SHORTAGES:

Pandemic social distancing requirements meant fewer workers on the floor.

FEWER MILLS:

Since the financial crisis of 2008-2009, many sawmills have closed.

Demand:

MORE BUILDINGS:

With housing inventory and interest rates at record lows, construction of new homes increased rapidly insome regions.

MORE PROJECTS:

With people spending more time at home during lockdowns—some with increased savings—projects like new decks and fences increased demand.