Tiny pests eating New Jersey's pines march north as climate changes, report says

Love the warmer winters we’ve been enjoying? So does the southern pine beetle, a rice-grain-sized pest that has munched through New Jersey’s pine forests and could be a harbinger of climate change, according to a new study.

Using the Garden State as a barometer, researchers from Columbia University, the University of Vermont and the U.S. Forestry Service measured temperatures and their relationship to where the beetles were spreading.

They found that the temperature of tree bark on the coldest night of the year is critical. The destructive pests feed on the living tissue under the bark, introducing blue stain fungi. If the bark remains cold enough, the pests can’t do their damage.

But the temperature on the coldest night of the year in New Jersey has been rising due to climate change, the researchers say, creating a path for the insect to start an invasion that eventually will spread into into the northern United States and southern Canada. The lows are rising much faster than average temperatures, they said.

Southern New Jersey is critical because of its 440,000 acres of pine forests. The researchers picked the southern pine beetle as a climate change focus because it seems so sensitive to temperature. And, it is responsible for destroying $1.7 billion worth of timber between 1990 and 2014 in southeastern states.

“I think the presence and destructiveness of the southern pine beetle in New Jersey is well established. It’s been a problem for 15 years,” said co-author Corey Lesk, a PhD candidate at Columbia University’s Center for Climate Systems Research. The study was published Monday in the research journal Nature Climate Change.

“But it’s spreading north rather quickly,” Lesk said. “Our study uses the data from southern New Jersey in relation to how it’s moving north. The coldest night of the winter seems to dictate whether the southern pine beetle can live.”

The group established that bark temperature of about -10 Celsius, or about 14 degrees Fahrenheit, is the limit at which the beetle can survive. Since 1980, they found, the coldest night of the year above 14-degrees has migrated north in New Jersey by about 40 miles per decade. And the beetles have been moving north too, by about 53 miles per decade since 2002. The cold weather connection has long been known. But the new study predicts how far and fast the beetles will spread, given warming temperatures. Using historic climate data, the team projects that the annual minimum air temperature will continue to rise a few degrees per year in the northeast.