The future increase of methane concentration leads to a raise in water vapor abundance in the middle atmosphere. This will enhance the brightness of noctilucent clouds (NLC). We use an atmospheric background model and a microphysical model to study the associated absorption of solar radiation in the period 1950 to 2100. At 69°N mean absorptions at λ=126nm will increase from ~3% to ~7% from 1950 to 2100, respectively. Locally, the absorption can increase to ~30% in the year 2100. In the visible we find an increase from 0.0030% (1950) to 0,020% (2100), i.e., by a factor of ~7, and local maxima up to 0.35% in 2100. The results are similar for polar latitudes (79°N) but are smaller at middle latitudes (58°N). Future mean absorptions are comparable to solar cycle variations, but much larger locally. The ice mass bound in NLC increases from 677 to 1871 tons in 1950 and 2100.