Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/8195
AuthorsPatara, L.* 
Vichi, M.* 
Masina, S.* 
TitleImpacts of natural and anthropogenic climate variations on North Pacific plankton in an Earth System Model
Issue Date2012
Series/Report no.10/244(2012)
DOI10.1016/j.ecolmodel.2012.06.012,
URIhttp://hdl.handle.net/2122/8195
KeywordsPlankton model; Biogeochemistry; Physiological stoichiometry; Natural climate variability; Climate change; North Pacific; Earth System Model
Subject Classification03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling 
03. Hydrosphere::03.01. General::03.01.03. Global climate models 
03. Hydrosphere::03.01. General::03.01.07. Physical and biogeochemical interactions 
03. Hydrosphere::03.04. Chemical and biological::03.04.01. Biogeochemical cycles 
03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling 
03. Hydrosphere::03.04. Chemical and biological::03.04.04. Ecosystems 
AbstractThe impacts of natural atmospheric variability and anthropogenic climate change on the spatial distribution, seasonality, structure, and productivity of North Pacific plankton groups are investigated by means of an Earth System Model (ESM) that contains a plankton model with variable stoichiometry. The ESM is forced with observed greenhouse gases for the 20th century and with the Intergovernmental Panel on Climate Change A1B Emission Scenario for the 21st century. The impacts of the two main modes of variability – connected with the Aleutian Low (AL) strength and with the North Pacific Oscillation (NPO) – are considered. When the AL is strong, primary productivity and chlorophyll concentrations are higher in the central Pacific, the seasonality of plankton is enhanced, and the classical grazing chain is stimulated, whereas in the Alaskan Gyre the model simulates a chlorophyll decrease and a shift toward smaller phytoplankton species. A stronger NPO increases productivity and chlorophyll concentration at ∼45°N. In the anthropogenic climate change scenario, simulated sea surface temperature is 4 °C higher with respect to contemporary conditions, leading to reduced mixing and nutrient supply at middle-subpolar latitudes. The seasonal phytoplankton bloom is reduced and occurs one month earlier, the flow of carbon to the microbial loop is enhanced, and phytoplanktonic stoichiometry is nutrient-depleted. Primary productivity is enhanced at subpolar latitudes, due to increased ice-free regions and possibly to temperature-related photosynthesis stimulation. This study highlights that natural climate variability may act alternatively to strengthen or to weaken the human-induced impacts, and that in the next decades it will be difficult to distinguish between internal and external climate forcing on North Pacific plankton groups.
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