An updated assessment of changes in equilibrium moisture content of wood in Japan based on the Intergovernmental Panel on Climate Change sixth assessment report

The purpose of this study was to update the future projections of equilibrium moisture content of wood presented in the previous report based on the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. First, the future projections in the previous report were compared with the subsequent actual values, and the validity of the projection method in the previous report was examined. Next, following the forecasting method in the previous report, future projections of the annual average equilibrium moisture content of wood to the year 2100 were conducted based on the latest scenarios. Although the equilibrium moisture content of wood in various regions of Japan fell generally within the range predicted in the previous report during the 22-year period from 2001 to 2022, the slope of the decline was somewhat slower than predicted, suggesting that the method used in the previous report may slightly overestimate the equilibrium moisture content in the future. The equilibrium moisture content of wood will continue to decline at least until mid-century, and unless CO2 and other greenhouse gas emissions decrease substantially over the next few decades, equilibrium moisture content will decline by more than 1.5 to 2 percentage points during the 21st century.