Insect pests like forest tent caterpillar and diseases like Dutch elm disease may become more active and damaging in northern hardwoods in Wisconsin and western Upper Michigan under a warmer climate.

Under a high emissions scenario, researchers forecast more insect pest damage in northern forests due to increased metabolic activity in active periods and increased winter survival. Drought-stressed trees are also typically more vulnerable to insect pests and diseases. Emerald ash borer and Dutch elm disease are expected to continue to limit ash and elm species. New pests such as hemlock wooly adelgid may be able to persist if introduced.