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Challenges in the Paleoclimatic Evolution of the Arctic and Subarctic Pacific Since the Last Glacial Period—The Sino–German

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Challenges in the Paleoclimatic Evolution of the Arctic and Subarctic Pacific Since the Last Glacial Period—The Sino–German challenges Concept Paper Challenges in the Paleoclimatic Evolution of the Arctic and Subarctic Pacific since the Last Glacial Period—The Sino–German Pacific–Arctic Experiment (SiGePAX) Gerrit Lohmann 1,2,3,* , Lester Lembke-Jene 1 , Ralf Tiedemann 1,3,4, Xun Gong 1 , Patrick Scholz 1 , Jianjun Zou 5,6 and Xuefa Shi 5,6 1 Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung Bremerhaven, 27570 Bremerhaven, Germany; [email protected] (L.L.-J.); [email protected] (R.T.); [email protected] (X.G.); [email protected] (P.S.) 2 Department of Environmental Physics, University of Bremen, 28359 Bremen, Germany 3 MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany 4 Department of Geosciences, University of Bremen, 28359 Bremen, Germany 5 First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China; zoujianjun@fio.org.cn (J.Z.); xfshi@fio.org.cn (X.S.) 6 Pilot National Laboratory for Marine Science and Technology, Qingdao 266061, China * Correspondence: [email protected] Received: 24 December 2018; Accepted: 15 January 2019; Published: 24 January 2019 Abstract: Arctic and subarctic regions are sensitive to climate change and, reversely, provide dramatic feedbacks to the global climate. With a focus on discovering paleoclimate and paleoceanographic evolution in the Arctic and Northwest Pacific Oceans during the last 20,000 years, we proposed this German–Sino cooperation program according to the announcement “Federal Ministry of Education and Research (BMBF) of the Federal Republic of Germany for a German–Sino cooperation program in the marine and polar research”. Our proposed program integrates the advantages of the Arctic and Subarctic marine sediment studies in AWI (Alfred Wegener Institute) and FIO (First Institute of Oceanography). For the first time, the collection of sediment cores can cover all climatological key regions in the Arctic and Northwest Pacific Oceans. Furthermore, the climate modeling work at AWI enables a “Data-Model Syntheses”, which are crucial for exploring the underlying mechanisms of observed changes in proxy records. Keywords: paleoclimate; Pacific Ocean; Arctic climate; paleoclimate data; modeling; data-model comparison; proxy data 1. Introduction Paleoclimate studies in the Arctic and Subarctic Regions are of vital importance for a better understanding of the natural processes in the climate system that exclude the impacts of human activities. We carry out a German-Sino cooperative research program in marine and polar research which is based on an existing close cooperation in paleoclimate research between the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI, Germany), and the First Institute of Oceanography, Ministry of Natural Resources (FIO, China). In Germany, the program work is carried out by the Paleoclimate Dynamics Group (led by Prof. Dr. Gerrit Lohmann) (AWI), and the Marine Geology Group (led by Prof. Dr. Ralf Tiedemann) (AWI). In China, the cooperation research is going to be undertaken by the Lab of Marine Geology and Geophysics, in FIO (led by Prof. Dr. Challenges 2019, 10, 13; doi:10.3390/challe10010013 www.mdpi.com/journal/challenges Challenges 2019, 10, 13 2 of 22 Challenges 2019, 10, x FOR PEER REVIEW 2 of 22 Xuefa Shi). All three groups are renowned for their scientific achievements in this field. One visible achievement according toto thethe specifiedspecified researchresearch planplan willwill bebe thethe provision ofof aa data basis for a highly productiveproductive grid-basedgrid-based platform, which enables efficientefficient proxy and model data processing on anan internationalinternational level. Furthermore, Furthermore, our our program program also shows large potential in long-termlong-term benefitsbenefits forfor internationalinternational cooperation.cooperation. 2. The Research Area: Modern Ocean–Atmosphere Forcing, FreshwaterFreshwater Flux,Flux, SeaSea IceIce Patterns,Patterns, and Upperand Upper Ocean Ocean and Intermediateand Intermediate Water Water Circulation Circulation Today, surface surface and and deeper deeper waters waters are exchangedare exchanged between between the Arctic the Ocean,Arctic theOcean, subarctic the subarctic marginal seasmarginal and theseas open and Norththe open Pacific North through Pacific the through Bering the Strait, Bering as wellStrait, as as a serieswell as of a straits series andof straits passages and inpassages the Kurile in the and Kurile Aleutian and IslandAleutian chains, Island respectively chains, respectively [1,2]. New [1,2]. waters New mostly waters enter mostly the marginalenter the seasmarginal through seas large-scale through currentlarge-scale systems, current such system as the Alaskans, such Streamas the andAlaskan the East Stream Kamchatka and the Current East (FigureKamchatka1). Current (Figure 1). Figure 1.1. Bathymetric chart of the study region with major oceanic surface currents (orange arrows) fromfrom MaxMax etet al.al. [[3].3]. OCOC == OyashioOyashio Current;Current; EKCEKC == East Kamchatka Current; ANSCANSC == Aleutian NorthNorth Slope Current; BSCBSC == Bering Slope Current. The proposed region is linked via teleconnections to both high and low latitude climatic patterns, The proposed region is linked via teleconnections to both high and low latitude climatic patterns, making it an ideal, highly sensitive candidate to investigate coupling and interaction of major making it an ideal, highly sensitive candidate to investigate coupling and interaction of major polar polar and tropical climate mechanisms. The Arctic Oscillation and the strength of the Siberian and tropical climate mechanisms. The Arctic Oscillation and the strength of the Siberian High/Aleutian Low system in wintertime is one dominant factor for the amount of snow cover High/Aleutian Low system in wintertime is one dominant factor for the amount of snow cover and and winter strength [4–6], including the timing of sea ice onset and breakup (cf. Figure2)[ 7]. These winter strength [4–6], including the timing of sea ice onset and breakup (cf. Figure 2) [7]. These systems provide a link between the high northern latitudes in the Atlantic and Pacific realm. The East systems provide a link between the high northern latitudes in the Atlantic and Pacific realm. The East Asian Summer Monsoon system, on the other hand, delivers precipitation and heat from the tropics Asian Summer Monsoon system, on the other hand, delivers precipitation and heat from the tropics during the summer to the extratropical North Pacific and the continental hinterland major river during the summer to the extratropical North Pacific and the continental hinterland major river catchment areas [8–10]. These fluctuations in freshwater discharge, in turn, play an active role in catchment areas [8–10]. These fluctuations in freshwater discharge, in turn, play an active role in controlling sea ice formation and upper ocean hydrography [11]. controlling sea ice formation and upper ocean hydrography [11]. In addition to these upper ocean and atmospheric components, the North Pacific Ocean is In addition to these upper ocean and atmospheric components, the North Pacific Ocean is the the terminus of the global Meridional Overturning Circulation. No new deep-water masses are terminus of the global Meridional Overturning Circulation. No new deep-water masses are formed formed [12,13], and the deep North Pacific harbors the oldest and most CO2-enriched water masses in [12,13], and the deep North Pacific harbors the oldest and most CO2-enriched water masses in the the modern world ocean [14,15]. modern world ocean [14,15]. Only the mid-depth (500–1000 m) water layer in the North Pacific is replenished and ventilated by Only the mid-depth (500–1000 m) water layer in the North Pacific is replenished and ventilated newly formed North Pacific Intermediate Water (Figure3, abbr. NPIW), which is largely determined by newly formed North Pacific Intermediate Water (Figure 3, abbr. NPIW), which is largely by precursor water masses from the subarctic marginal seas [16,17], mainly the Okhotsk Sea and, determined by precursor water masses from the subarctic marginal seas [16,17], mainly the Okhotsk to a lesser extent, Bering Sea and Alaskan Gyre [16,18,19]. Residence and formation times of these Sea and, to a lesser extent, Bering Sea and Alaskan Gyre [16,18,19]. Residence and formation times of mid-depth waters are short and range between one and four years [1]. These fast response times these mid-depth waters are short and range between one and four years [1]. These fast response times make NPIW especially sensitive to anthropogenic global climate change on short, human timescales, make NPIW especially sensitive to anthropogenic global climate change on short, human timescales, as indicated by recent instrumental studies that show warming, freshening, and de-oxygenation in North Pacific mid-depth waters over the past ca. 50 years [20–23]. Challenges 2019, 10, 13 3 of 22 as indicated by recent instrumental studies that show warming, freshening, and de-oxygenation in ChallengesNorthChallenges Pacific 2019 2019, ,10 10 mid-depth, ,x x FOR FOR PEER PEER waters REVIEW REVIEW over the past ca. 50 years [20–23]. 33 ofof 2222 Figure 2. Schematic overview of forcing factors in the study area that influence sea surface temperatures FigureFigure 2.2. SchematicSchematic overviewoverview ofof forcingforcing factorsfactors inin thethe studystudy areaarea thatthat influenceinfluence seasea surfacesurface
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