The boreal forest is a natural climate-driven system, but with recent warming over the past several decades, it is important to distinguish climate change (warming) effect from natural variability of this system. This project overlaps with other projects that are determining radial growth responses to climate over the lifetime of a tree. It focuses on the four main species of the boreal forest: black and white spruce, birch and aspen. Cores and disks are being collected from all over boreal Alaska. Results suggest that there is a continuing high risk caused by climate warming in managing forest land in southcentral Alaska for spruce forest crops. Under recent climate conditions, and especially under scenarios of further climate warming, spruce bark beetle irruption potential will remain high. Small surviving understory spruce trees not susceptible to bark beetle attack in the region will mature to commercial forest dimensions and move into the prime susceptibility size and age classes to serve as hosts for spruce bark beetle. Under these circumstances, the regional environment would remain effectively saturated with spruce bark beetles because climate limitations on beetles have been removed. Investments in regeneration and early tending of new commercial stands of spruce would carry considerable risk because bark beetles would become effective agents of tree mortality at about the time that stands of spruce became large enough to generate commercial value.