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The Greenland Ice Sheet (GrIS) is a major contributor to sea level rise and may already be in irreversible decline. Observations spanning recent decades show the GrIS losing mass at an increasing rate; however, projecting this trend into the future is complicated by year-to-year variability and requires looking at longer timescales. Historical data suggest the GrIS was nearly in balance in the 1800s (-900 Gt/century), but had negative balance in the 1900s (-4000 to -8000 Gt/century). Projecting observations made thus far from the 2000s, mass-loss rate could average anywhere from ca. -40,000 to -100,000 Gt/century. Our goal is to evaluate these historic and contemporary rates of GrIS mass loss within the framework of the current Holocene interglacial spanning the last 12,000 years. To do so we combine the first highly resolved paleo-GrIS simulations using NASA's Ice Sheet System Model with novel climate forcing based on a data assimilation approach using multiple paleoclimate records. Our new simulations take place across a glaciologically simple domain in SW Greenland (encompassing ca. 30% of the ice sheet), where they are validated with our detailed glacial chronology of Holocene ice margin change. During the Holocene thermal maximum, a period between ca. 10,000 and 8000 years ago, the GrIS experienced elevated mass loss rates, with maximum values on the order of -5000 to -10,000 Gt/century for our model domain. When these values are scaled to the entire GrIS (using the proportion of SW mass loss vs. total GrIS mass loss from contemporary studies), they equate to maximum mass loss rates of ca. -20,000 to -40,000 Gt/century. From this we conclude that the rate of GrIS mass loss will exceed Holocene values this century.