Climate of The Past Discussions最新文献

{"title":"Climatic variations during the Holocene inferred from radiocarbon and stable carbon isotopes in a high-alpine cave","authors":"C. Welte, J. Fohlmeister, Melina Wertnik, L. Wacker, B. Hattendorf, T. Eglinton, C. Spötl","doi":"10.5194/CP-2020-110","DOIUrl":"https://doi.org/10.5194/CP-2020-110","url":null,"abstract":"<div>\u0000<p>Laser ablation coupled online to accelerator mass spectrometry [1] allows analyzing the radiocarbon (¹⁴C) concentration in carbonate samples in a fast and spatially resolved manner. This novel technique can provide ¹⁴C data at a spatial resolution comparable to that of stable carbon isotope measurements and, thus, can help to interpret &#948;¹³C signatures. In this work, we analyzed &#948;¹³C and ¹⁴C of a Holocene stalagmite from the high-alpine Spannagel Cave (Austria). Combined &#948;¹³C and ¹⁴C profiles allow identifying three growth periods : (i) the period > 8 ka BP exhibits relatively low &#948;¹³C values with small variability combined with a comparably high dead carbon fraction (dcf) of around 60%. This points towards C contributions of an old organic carbon reservoir in the karst potentially mobilized due to the warm climatic conditions of the early Holocene. (ii) Between 3.8 and 8 ka BP, a strong variability in &#948;¹³C with values from -8 to +1&#8240; and a generally lower dcf was observed. The &#948;¹³C variability was most likely caused by changes in gas exchange processes in the cave, which are induced by reduced drip rates as derived from lower stalagmite growth rates. Additionally, the lower dcf indicates that the OM reservoir contributed less to stalagmite growth in this period possibly as a result of reduced precipitation or because the OM reservoir became exhausted. (iii) In the youngest section between 2.4 and 3.8 ka BP, comparably stable and low &#948;¹³C values combined with an increasing dcf reaching up to 50% are again hinting towards a contribution of an aged organic carbon reservoir in the karst.</p>\u0000</div><p>[1] C. Welte, et al., (2016). Anal. Chem., 88, 8570&#8211; 8576.</p>","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116140406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate, cryosphere and carbon cycle controls on Southeast Atlantic orbital-scale carbonate deposition since the Oligocene (30–0 Ma)","authors":"A. Drury, D. Liebrand, T. Westerhold, H. Beddow, D. Hodell, Nina Rohlfs, R. Wilkens, M. Lyle, D. Bell, D. Kroon, H. Pälike, L. Lourens","doi":"10.5194/cp-2020-108","DOIUrl":"https://doi.org/10.5194/cp-2020-108","url":null,"abstract":"Abstract. The evolution of the Cenozoic Icehouse over the past 30 million years (Myr) from a unipolar to a bipolar world is broadly known; however, the exact development of orbital-scale climate variability is less well understood. Highly resolved records of carbonate (CaCO3) content provide insight into the evolution of regional and global climate, cryosphere and carbon cycle dynamics. Here, we generate the first Southeast Atlantic CaCO3 content record spanning the last 30 Myr, derived from X-ray fluorescence (XRF) ln(Ca/Fe) data collected at Ocean Drilling Program Site 1264 (Angola Basin side of the Walvis Ridge, SE Atlantic Ocean). We present a comprehensive and continuous depth and age model for the entirety of Site 1264 (~316 m; 30 Myr), which constitutes a key reference framework for future palaeoclimatic and palaeoceanographic studies at this site. We identify three phases with distinctly different orbital controls on Southeast Atlantic CaCO3 deposition, corresponding to major developments in climate, the cryosphere and/or the carbon cycle: 1) strong ~110 kyr eccentricity pacing prevails during Oligo-Miocene global warmth (~30–13 Ma); 2) increased eccentricity-modulated precession pacing appears after the mid Miocene Climate Transition (mMCT) (~14–8 Ma); 3) strong obliquity pacing appears in the late Miocene (~7.7–3.3 Ma) following the increasing influence of high-latitude processes. The lowest CaCO3 content (92–94 %) occur between 18.5–14.5 Ma, potentially reflecting dissolution caused by widespread early Miocene warmth and preceding Antarctic deglaciation across the Miocene Climate Optimum (~17–14.5 Ma) by 1.5 Myr. The emergence of precession-pacing of CaCO3 deposition at Site 1264 after ~14 Ma could signal a reorganisation of surface and/or deep-water circulation in this region following Antarctic reglaciation at the mMCT. The increased sensitivity to precession at Site 1264 is associated with an increase in mass accumulation rates (MARs) and reflects increased regional CaCO3 productivity and/or an influx of cooler, less corrosive deep-waters. The highest %CaCO3 and MARs indicate the late Miocene Biogenic Bloom (LMBB) occurs between ~7.8–3.3 Ma at Site 1264, which is broadly, but not exactly, contemporaneous with the LMBB in the equatorial Pacific Ocean. The global expression of the LMBB may reflect an increased nutrient input into the global ocean resulting from enhanced aeolian dust and/or glacial/chemical weathering fluxes. Regional variability in the timing and amplitude of the LMBB may be driven by regional differences in cooling, continental aridification and/or changes in ocean circulation in the late Miocene.\u0000","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121989774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early Pliocene deepening of the tropical Atlantic thermocline","authors":"C. V. D. van der Weijst, J. Winkelhorst, A. S. von der Heydt, G. Reichart, F. Sangiorgi, A. Sluijs","doi":"10.5194/cp-2020-105","DOIUrl":"https://doi.org/10.5194/cp-2020-105","url":null,"abstract":"Abstract. The tropical thermocline may have played a crucial role in maintaining weaker sea surface temperature gradients during the early Pliocene and in the onset of late Pliocene northern hemisphere glaciation. Whereas the Pliocene Pacific thermocline evolution is well documented, complete records of Pliocene tropical Atlantic thermocline depths are limited to the Caribbean region. Here, we use the oxygen isotope gradient between surface to subsurface dwelling planktic foraminifera from Ocean Drilling Program Site 959 in the eastern equatorial Atlantic to track vertical changes in thermocline depth over the course of the Pliocene. This record shows that eastern equatorial Atlantic thermocline depth varied substantially during the early Pliocene, before finally deepening abruptly around 4.5 Ma to remain relatively stable until at least 2.8 Ma. Eastern equatorial Atlantic and Caribbean records are almost identical, suggesting a common control on the sudden step-wise thermocline deepening across the basin, in contrast to previous assumptions. The Pliocene evolution of the tropical Atlantic thermocline differs is remarkably from the Pacific, which is characterized by gradual basin-wide shoaling. It remains unclear what mechanisms were involved in the dichotomous thermocline evolutions. Whereas Central American Seaway closure may have shoaled the Pacific thermocline, it is not yet understood if and how this process may have deepened the Atlantic thermocline. A divergent evolution of temperatures of the source regions may explain the opposite thermocline developments observed, possibly amplified by a positive feedback loop involving tropical cyclone intensity.","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123784620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Greenland climate simulations show high Eemian surface melt","authors":"A. Plach, B. Vinther, K. Nisancioglu, Sindhu Vudayagiri, T. Blunier","doi":"10.5194/cp-2020-101","DOIUrl":"https://doi.org/10.5194/cp-2020-101","url":null,"abstract":"Abstract. This study presents simulations of Greenland surface melt for the Eemian interglacial period (~130000 to 115000 years ago) derived from regional climate simulations with a coupled surface energy balance model. Surface melt is of high relevance for ice core records because it can influence observations, e.g., lower the preserved total air content (TAC) used to infer past surface elevation. An investigation of surface melt is particularly interesting for warm periods, such as the Eemian interglacial period, with enhanced surface melt. Furthermore, Eemian ice is the deepest and most compressed ice preserved on Greenland, which means that melt layers can not be identified visually. Therefore, a knowledge of potential melt layers would be advantageous. The simulations presented here show Eemian surface melt at all deep Greenland ice core locations. Estimated TAC, based on simulated melt during the Eemian, could explain the lower TAC observations: at the summit of Greenland (GRIP) a refreezing ratio of more than 25 % of the annual accumulation is simulated. As a consequence, elevated levels of surface melt during warm periods should be considered when interpreting Greenland TAC measurements as surface elevation changes. Additionally to estimating the influence of melt on past TAC in ice cores, the simulated surface melt could also be used to identify potential coring locations where Greenland ice might be best preserved.","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129290167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryptotephra from the Icelandic Veiðivötn 1477 CE eruption in a Greenland ice core: confirming the dating of 1450s CE volcanic events and assessing the eruption's climatic impact","authors":"P. Abbott, G. Plunkett, C. Corona, N. Chellman, J. McConnell, J. Pilcher, M. Stoffel, M. Sigl","doi":"10.5194/cp-2020-104","DOIUrl":"https://doi.org/10.5194/cp-2020-104","url":null,"abstract":"Abstract. Volcanic eruptions are a key source of climatic variability and reconstructing their past impact can improve our understanding of the operation of the climate system and increase the accuracy of future climate projections. Two annually resolved and independently dated palaeoarchives – tree rings and polar ice cores – can be used in tandem to assess the timing, strength and climatic impact of volcanic eruptions over the past ~ 2500 years. The quantification of post-volcanic climate responses, however, has at times been hampered by differences between simulated and observed temperature responses that raised questions regarding the robustness of the chronologies of both archives. While many chronological mismatches have been resolved, the precise timing and climatic impact of one or more major sulphate emitting volcanic eruptions during the 1450s CE, including the largest atmospheric sulphate loading event in the last 700 years, has not been constrained. Here we explore this issue through a combination of tephrochronological evidence and high-resolution ice-core chemistry measurements from the TUNU2013 ice core. We identify tephra from the historically dated 1477 CE eruption of Veiðivotn-Barðarbunga, Iceland, in direct association with a notable sulphate peak in TUNU2013 attributed to this event, confirming that it can be used as a reliable and precise time-marker. Using seasonal cycles in several chemical elements and 1477 CE as a fixed chronological point shows that ages of 1453 CE and 1458/59 CE can be attributed, with a high accuracy, to two notable sulphate peaks. This confirms the accuracy of the NS1-2011 Greenland ice-core chronology over the mid- to late 15th century and corroborate the findings of recent volcanic reconstructions from Greenland and Antarctica. Overall, this implies that large-scale Northern Hemisphere climatic cooling affecting tree-ring growth in 1453 CE was caused by a Northern Hemisphere volcanic eruption in 1452 CE and then a Southern Hemisphere eruption, previously assumed to have triggered the cooling, occurred later in 1458 CE. The direct attribution of the 1477 CE sulphate peak to the eruption of Veiðivotn, the most explosive from Iceland in the last 1200 years, also provides the opportunity to assess its climatic impact. A tree-ring based reconstruction of Northern Hemisphere summer temperatures shows a cooling of −0.35 °C in the aftermath of the eruption, the 356th coldest summer since 500 CE, a relatively weak and spatially incoherent climatic response in comparison to the less explosive but longer-lasting Icelandic Eldgja 939 CE and Laki 1783 CE eruptions, that ranked as the 205th and 9th coldest summers respectively. In addition, the Veiðivotn 1477 CE eruption occurred around the inception of the Little Ice Age and could be used as a chronostratigraphic marker to constrain the phasing and spatial variability of climate changes over this transition if it can be traced into more regional palaeoclimatic a","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"125 19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127346623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate-driven desertification triggered the end of the Ancient Silk Road","authors":"G. Dong, Leibin Wang, D. Zhang, Fengwen Liu, Yifu Cui, Guoqiang Li, Zhilin Shi, Fahu Chen","doi":"10.5194/cp-2020-102","DOIUrl":"https://doi.org/10.5194/cp-2020-102","url":null,"abstract":"Abstract. The Ancient Silk Road played a crucial role in cultural exchange and commercial trade between western and eastern Eurasia during the historical period. However, the exchanges were interrupted in the early 16th century AD, in the Ming dynasty. Three causes of the demise of the ancient Silk Road have been suggested: (1) the thriving of the sea trade route after the great geographic discovery in the Ming dynasty; (2) frequent incursions by the Wala and Turpan kingdoms, or fighting in border areas; and (3) climate change. In this study, new evidence from a sedimentary site in Dunhuang oasis together with analysis of historical archives indicate that neither the sea trade route nor the frontier wars were the pivotal reason for the closure of the Jiayuguan Pass. Extreme droughts and desertification events, caused by climate change, occurred in the Dunhuang area, west of the Jiayuguan Pass, during ~ 1440–1460 AD. After ~ 1450 AD, desertification rendered the ancient Silk Road impassable in the area, which resulted in a steep fall in the volume of trade as well as political chaos and mass migrations. The final closure of the Jiayuguan Pass in 1539 AD and the abandonment of Dunhuang city further interrupted the operation of the ancient Silk Road.","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134564779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the utility of qualitative data in precipitation reconstruction in the eighteenth and nineteenth centuries","authors":"A. Harvey-Fishenden, N. Macdonald","doi":"10.5194/cp-2020-90","DOIUrl":"https://doi.org/10.5194/cp-2020-90","url":null,"abstract":"Abstract. To date few studies have reconstructed weather from personal diaries. In this paper, we consider different methods of indexing daily weather information, specifically precipitation, from eighteenth and nineteenth century personal diaries. We examine whether there is a significant correlation between indexed weather information and local instrumental records for the period, thereby assessing the potential of discursive materials in reconstructing precipitation series. We demonstrate the potential for the use of diaries that record weather incidentally rather than as the primary purpose, and the value and utility of diaries which cover short periods when used alongside nearby contemporary diaries. We show that using multiple overlapping personal diaries can help to produce a more objective record of the weather, overcoming some of the challenges of working with qualitative data. This paper demonstrates indices derived from such qualitative sources can create valuable records of precipitation. There is the potential to repeat the methodology described here using earlier material, or material from further away from extant instrumental records, thereby addressing spatial and temporal gaps in current knowledge globally.\u0000","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130224276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Eccentricity-paced atmospheric carbon-dioxide variations across the\u0000middle Miocene climate transition","authors":"M. Raitzsch, J. Bijma, T. Bickert, M. Schulz, A. Holbourn, M. Kučera","doi":"10.5194/cp-2020-96","DOIUrl":"https://doi.org/10.5194/cp-2020-96","url":null,"abstract":"Abstract. The middle Miocene climate transition ~ 14 Ma marks a fundamental step towards the current “icehouse” climate, with a ~ 1 ‰ δ18O increase and a ~ 1 ‰ transient δ13C rise in the deep ocean, indicating rapid expansion of the East Antarctic Ice Sheet associated with a change in the operation of the global carbon cycle. The variation of atmospheric CO2 across the carbon-cycle perturbation has been intensely debated as proxy records of pCO2 for this time interval are sparse and partly contradictory. Using boron isotopes (δ11B) in planktonic foraminifers from drill site ODP 1092 in the South Atlantic, we show that long-term pCO2 variations between ~ 14.3 and 13.2 Ma were paced by 400 k.y. eccentricity cycles, with decreasing pCO2 at high eccentricity and vice versa. Our data support results from a carbon-cycle model study, according to which increased monsoon intensity at high eccentricity enhanced weathering and river fluxes in the tropics, resulting in increasing carbonate and organic carbon burial and hence decreasing atmospheric CO2. In this scenario, a combination of the eccentricity-driven climatic cycle and enhanced meridional deep-ocean circulation during Antarctic ice-sheet expansion may have both contributed to the pCO2 rise following Antarctic glaciation, acting as a negative feedback on the progressing glaciation and helping to stabilize the climate system on its way to the late Cenozoic “icehouse” world.","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122224174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LGM climate forcing and ocean dynamical feedback and their implications for estimating climate sensitivity","authors":"Jiang Zhu, C. Poulsen","doi":"10.5194/cp-2020-86","DOIUrl":"https://doi.org/10.5194/cp-2020-86","url":null,"abstract":"Abstract. Equilibrium climate sensitivity (ECS) has been directly estimated using reconstructions of past climates that are different than today’s. A challenge to this approach is that temperature proxies integrate over the timescales of the fast feedback processes (e.g. changes in water vapor, snow, and clouds) that are captured in ECS as well as the slower feedback processes (e.g. changes in ice sheets and ocean circulation) that are not. A way around this issue is to treat the slow feedbacks as climate forcings and independently account for their impact on global temperature. Here we conduct a suite of Last Glacial Maximum (LGM) simulations using the Community Earth System Model version 1.2 (CESM1.2) to quantify the forcing and efficacy of land ice sheets (LIS) and greenhouse gases (GHG) in order to estimate ECS. Our forcing and efficacy quantification adopts the effective radiative forcing (ERF) and adjustment framework and provides a complete accounting for the radiative, topographic, and dynamical impacts of LIS on surface temperatures. ERF and efficacy of LGM LIS are −3.2 W m−2 and 1.1, respectively. The larger-than-unity efficacy is caused by the relatively larger temperature changes over land and the Northern Hemisphere subtropical oceans than those in response to a doubling of atmospheric CO2. The subtropical SST response is linked to LIS-induced wind changes and feedbacks in ocean-atmosphere coupling and clouds. ERF and efficacy of LGM GHG are −2.8 W m−2 and 0.9, respectively. The lower efficacy is primarily attributed to a smaller cloud feedback at colder temperatures. Our simulations further demonstrate that the direct ECS calculation using the forcing, efficacy, and temperature response in CESM1.2 overestimates the true value in the model by 25 % due to the neglect of slow ocean dynamical feedback. This is supported by the greater cooling (6.8 °C) in a fully coupled LGM simulation than that (5.3 °C) in a slab ocean model simulation with ocean dynamics disabled. The majority (67 %) of the ocean dynamical feedback is attributed to dynamical changes in the Southern Ocean, where interactions between ocean stratification, heat transport, and sea-ice cover are found to amplify the LGM cooling. Our study demonstrates the value of climate models in the quantification of climate forcings and the ocean dynamical feedback, which is necessary for an accurate direct ECS estimation.","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125421095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atmospheric Fe supply has a negligible role in promoting marine productivity in the Glacial North Pacific Ocean","authors":"F. Burgay, A. Spolaor, J. Gabrieli, G. Cozzi, C. Turetta, P. Vallelonga, C. Barbante","doi":"10.5194/cp-2020-77","DOIUrl":"https://doi.org/10.5194/cp-2020-77","url":null,"abstract":"Abstract. Iron is a key element in the Earth climate system as it can enhance the marine primary productivity in the High-Nutrient Low-Chlorophyll (HNLC) regions where, despite a high concentration of major nutrients, the chlorophyll production is low due to iron limitation. One of the main Fe sources to the ocean is Aeolian dust. For this reason, ice cores provide a sensitive and continuous archive for reconstructing Fe fluxes over the last millennia. Here we show the first Northern Hemisphere Fe record retrieved from the NEEM ice core, which offers a unique opportunity to reconstruct the past Fe fluxes in the Arctic region over the last 108 kyr. Holocene Fe fluxes to the Arctic were three times lower than the average recorded over the last glacial period. They were greater during the Last Glacial Maximum (LGM) and the Marine Isotope Stage 4 (MIS 4). Comparing our data with palaeoceanographic records retrieved from the HNLC North Pacific, we demonstrated that during the coldest periods, characterized by the highest Fe fluxes, marine productivity in the subarctic Pacific Ocean did not increase due to a greater sea-ice extent and the absence of upwelling nutrient supply. This supports the hypothesis that Fe-fertilization was more effective in other regions, such as the transition zone of the North Pacific, where a closer relationship between marine productivity and the Aeolian Fe fluxes was observed.","PeriodicalId":263057,"journal":{"name":"Climate of The Past Discussions","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129587107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}