19We investigated marine and terrestrial environmental changes at the northern 20 Japan margin in the northwestern Pacific during the last 23,000 years by analyzing 21 biomarkers (alkenones, long-chain n-alkanes, long-chain n-fatty acids, and 22 lignin-derived materials) in Core GH02-1030. The U 37 K ' -derived temperature in the last 23 2 glacial maximum (LGM) centered at 21 ka was ~10˚C, which was 2˚C lower than the 24 core-top temperature (~12˚C). This small temperature drop does not agree with pollen 25 evidence of a large air temperature drop (more than 4˚C) in the Tokachi area. This 26 disagreement might be attributed to a bias of U 37 K ' -derived temperature within 2.5˚C by 27 a seasonal shift in alkenone production. The U 37 K ' -derived temperature was significantly 28 low during the last deglaciation. Because this cooling was significant in the 29Kuroshio-Oyashio transition zone, the temperature drops are attributable to the 30 southward displacement of the Kuroshio-Oyashio boundary. Abundant lignin-derived 31 materials, long-chain n-alkanes and long-chain n-fatty acids indicate a higher 32 contribution of terrigenous organic matter from 17 to 12 ka. This phenomenon might 33 have resulted from an enhanced coastal erosion of terrestrial soils due to marine 34 transgression and/or an efficient inflow of higher plant debris to river waters from 17 to 35 12 ka. 36 37