Methanesulfonate (MS^-) is measured in ice cores with the objective to obtain a proxy record of marine phytoplankton production of dimethylsulfide (DMS). We present a continuous MS^- record covering the last glacial period from the North Greenland Ice Core Project (NGRIP) ice core and compare this record with the corresponding records previously presented from Greenland and, in particular, with the GISP2 ice core located 320 km south of NGRIP. Despite that the records have similar mean concentrations, their responses to climatic changes during the last glacial period are slightly different. NGRIP MS^- concentrations were higher during the cold marine isotopic stages (MIS) 2 and 4 and lower during the warm MIS 5. This long-term trend in MS^-, which is similar to the inverse of the corresponding trend in d ¹⁸O, is not detected in the GISP2 MS^- record. A systematic response in MS^- concentrations to changes between Greenland stadials and interstadials is only detected in the GISP2 record. The different responses of the MS^- signals to climate change during the last glacial period are possibly related to the partitioning of air masses reaching the two sites. In contrast to observations from Antarctic records, dust concentrations do not affect the MS^- concentrations in the ice, whereas the deposition of sulfate probably is enhanced by high dust concentrations in the atmosphere. The MS^- signal has a higher potential of being a proxy record of DMS production changes in Greenlandic compared to Antarctic ice cores.
Udgivelsesdato: 31 July