Biogenic opal and ice-rafted detritus (IRD) data from sediments in the Okhotsk Sea and the neighboring North Pacific revealed the remarkable reduction in opal production and southward advancement of sea-ice covered area during the last glacial maximum, resulting also southward shift of high biological productive area in the northwestern North Pacific. It implies that the substantial reduction in outflux of CO2 to the atmosphere in northwestern North Pacific and the pronounced increase in CO2 sequestering in temperate North Pacific. This could be an additional CO2 reduction mechanism of atmospheric CO2 in the last glacial period.