Arto Miettinen

• Ph.D.
• Docent of Quaternary Geology at University of Helsinki

Diatom inferred 2900-year-long records of August sea surface temperature (aSST) and April sea-ice concentration (aSIC) are generated from a marine sediment core from the SE Greenland shelf with a special focus on the interval ca. 870–1910 Common Era (CE) reconstructed in subdecadal temporal resolution. The Medieval Climate Anomaly (MCA) between 1...

A prominent characteristic of the reconstructed Northern Hemisphere temperature signal over the last millennium is the transition from the Medieval Climate Anomaly to the Little Ice Age (LIA). Here we report indications for a non-linear regime shift in the North Atlantic ocean circulation at the onset of the LIA. Specifically, we apply a novel stat...

A 2800-yr-long August sea surface temperature (aSST) record based on fossil diatom assemblages is generated from a marine sediment core from the northern subpolar North Atlantic. The record is compared with the aSST record from the Norwegian Sea to explore the variability of the aSST gradient between these areas during the late Holocene. The aSST r...

August Sea Surface Temperatures (aSSTs) based on fossil diatom assemblages are generated with 2year average resolution from a 230-year-long sediment core (Rapid 21-12B), from the Reykjanes Ridge in the subpolar North Atlantic. The results indicate a warming trend of ~0.5°C of the surface waters at the Reykjanes Ridge for the last 230years. Superimp...

The Holocene Thermal Maximum (HTM) is a significant warm period of the Holocene epoch, occurring between 11 and 6 ka BP. Here we present a multidecadal-to-centennial scale resolution diatom-based quantitative reconstruction of August Sea surface temperature (aSST) from Kongsfjorden, Svalbard for the regional HTM period between 10.5 and 7.5 ka BP. W...

Some of the most visible signs of climate change can be found in the northern high latitude region. Due to dynamic glacial-marine contrast, sedimentary geochemical proxies from western Svalbard fjords may provide a detailed account of paleoenvironmental changes in the region. We constructed a multivariate sedimentary record from a high-Arctic fjord...

On the remote Arctic archipelago of Svalbard, there is increasing evidence of environmental impacts from climate change. The analysis of lake sedimentary records can be used to assess how strongly these recent changes have altered lake ecosystems. Sediments deposited during the last millennium from Lake Blokkvatnet, Prins Karls Forland, were analys...

Environmental changes for the past ca. 50 years were studied in a short sediment core from inner Krossfjorden, Svalbard, investigating benthic foraminifera and stable isotopes (δ¹⁸O, δ¹³C). A depth–age model based on anthropogenic ¹³⁷Cs time markers indicates that record covers the period from 1955 to 2007 and has sediment accumulation rates of ca....

Despite the exclusion of the Southern Ocean from assessments of progress towards achieving the Convention on Biological Diversity (CBD) Strategic Plan, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has taken on the mantle of progressing efforts to achieve it. Within the CBD, Aichi Target 11 represents an agreed c...

Antarctic sea ice has paradoxically become more extensive over the past four decades despite a warming climate. The regional expression of this trend has been linked to changes in vertical redistribution of ocean heat and large-scale wind-field shifts. However, the short length of modern observations has hindered attempts to attribute this trend to...

A high-resolution marine sediment core NP16-Kro1-MCB from Krossfjorden, Western Svalbard is studied to investigate changes in sea surface conditions in the fjord during the last 60 years (1953–2014). The diatom-based reconstruction of August sea surface temperature (aSST) demonstrates a clear warming trend of 0.6 °C through the record. As inferred...

A high-resolution marine sediment core NP16-Kro1-MCB from Krossforden, Western Svalbard is studied to investigate changes in sea surface conditions in the ford during the last 60 years (1953–2014). The diatom-based reconstruction of August sea surface temperature (aSST) demonstrates a clear warming trend of 0.6 °C through the record. As inferred fr...

In recent decades the surface water temperature and salinity in the Labrador Sea have been influenced by atmospheric circulation patterns, such as the North Atlantic Oscillation (NAO), as well as a trend to increasingly warm atmospheric temperatures in recent years. These changes are concerning, given the important role that temperature and salinit...

Centennial- and millennial-scale variability of Southern Ocean temperature over the Holocene is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variations in the region coming mainly from ice core records. Here we present a high-resolution...

Abstract. Centennial and millennial scale variability of Southern Ocean temperature is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variability instead coming mainly from ice core records. Here we present a high-resolution (~ 60 year), d...

A long-term perspective is essential for understanding environmental change. To be able to access the past, environmental archives such as marine and lake sediments that store information in the form of diverse proxy records are used. Whilst many analytical techniques exist to extract the information stored in these proxy records, the critical asse...

The file contains an inventory of the archive of slides with fossil marine planktic diatoms from a network of sediment cores and surface sediment samples, including core tops. The collection of slides was prepared in NPI over the period from 1980s to 2019. The slides are packed in 83 diatom slide boxes and placed in 2 larger cardboard boxes (flytte...

Kongsfjorden, a fjord in north-western Svalbard, is characterized by large environmental gradients driven by meltwater processes along the margins of tidewater glaciers and the inflow of relatively warm Atlantic Water, the main heat source for the European Arctic. These factors make Kongsfjorden a key area to investigate changes in the polar climat...

Sound knowledge of present-day diatom species and their environments is crucial when attempting to reconstruct past climate and environmental changes based on fossil assemblages. For the North Atlantic region, the biogeography and ecology of many diatom taxa that are used as indicator-species in paleoceanographic studies are still not well known. U...

Paleoclimate research define the baselines for the natural climate change and is imperative to help us to set the recent observed changes in the long-term natural climate context. Fossil marine diatoms have proved to be an excellent tools for the paleoclimatic reconstructions, e.g. for the reconstruction of sea surface temperature (SST) and sea ice...

The SSF funded project “Sediment flux from source to sink – the Coastal Link” is an international, multi-disciplinary research project aiming at understanding and quantifying sediment distribution patterns in Svalbard fjords. The current project (2016-2017) focuses on Kongsfjorden and Dicksonfjorden as representatives for glacially and non-glaciall...

The transition from the last ice age to the present-day interglacial was interrupted by the Younger Dryas (YD) cold period. While many studies exist on this climate event, only few include high-resolution marine records that span the YD. In order to better understand the interactions between ocean, atmosphere and ice sheet stability during the YD,...

Paleoclimate records are crucial for understanding current changes taking place in the Arctic, e.g., the amplified warming and associated changes in sea-ice cover. However, paleoclimate and -oceanographic reconstructions, especially from the high Arctic, are scarce. Here, we present a reconstruction of sea surface and paleoenvironmental conditions...

Holocene oceanographic conditions in Disko Bay, West Greenland were reconstructed from high-resolution diatom records derived from two marine sediment cores. A modern dataset composed of 35 dated surface sediment samples collected along the entire West Greenland coast accompanied by remote sensing data were used to develop a diatom transfer functio...

Abstract We discuss a proboscidean bone fragment discovered in southern Finland, including the morphological analysis of the bone, as well as pollen and diatom analyses from sediment contained in the marrow cavity. Preliminary analysis of the bone suggested petrification and thus an apparently old age, while the microfossil assemblages include num...

A 2900-year-long diatom inferred August sea surface temperature reconstruction, at a temporal resolution of 3-8 years for 870-1910 CE and a at resolution of 40 years for 880 BCE-870 CE, from marine sediment core MD99-2322 from the SE Greenland shelf. An improved training set consisting of 184 surface sediment samples with 52 diatom species from the...

A 2900-year-long diatom inferred reconstruction of April sea ice concentrations was generated from marine sediment core MD99-2322 from the SE Greenland shelf. The reconstruction has a temporal resolution of 3-8 years for 870-1910 CE and a resolution of 40 years for 880 BCE-870 CE. The calibration set comprising 89 surface sediment samples from the...

The classical Maximum Density data of 65 Torneträsk trees from years 441 to 1980 AD are studied in millennial, centennial and volcanic scales. The millennial scale is analyzed applying a specific filtering method. In that scale, the climate is cool after 1200–1400 AD. This more or less steady period is suggested to be due to volcanic episodes, whic...

In total, 39 diatom species belonging to 22 genera were identified and photographed from Holocene marine sediment cores of Eastern Newfoundland bays. The cores were retrieved from Placentia Bay in the southeast and Bonavista Bay in the northeast of Newfoundland. The study area lies at the meeting point of the cold Labrador Current and the warmer Gu...

Preservation of diatoms in sediments of the North Atlantic and Arctic Ocean through geological time has been highly variable. The North Atlantic Ocean and the Nordic Seas were a region of high productivity of biogenic silica until the onset of Northern Hemisphere glaciations during the late Miocene. Later, fluctuating Pleistocene climatic condition...

The main criticism of the validity of the diatom test for the diagnosis of drowning is based on the potential ante- and post-mortem penetration of diatoms and the finding of diatoms in bodies of non-drowned human beings. However, qualitative and quantitative studies on diatoms in organs of the non-drowned have yielded both conflicting and contradic...

The Arctic region has undergone very rapid changes in the past 50 years. Climate models predict accelerating rates of change in the Arctic and long-term perspectives on natural climate variability are therefore needed to understand these changes and their further effects. We used marine fossil diatom assemblages from Baffin Bay to investigate Augus...

A 2800-yr-long August sea surface temperature (aSST) record based on fossil diatom assemblages is generated from a marine sediment core Rapid 21-COM recovered in the Iceland Basin (northern subpolar North Atlantic). The record has a resolution of 2-10 years for interval 800-2004 AD representing the best resolved diatom SST reconstruction from the s...

The marine diatom Neodenticula seminae belongs to the present day planktonic assemblage of the subarctic North Pacific and its high-latitude marginal seas. In the middle and high-latitude North Atlantic, N. seminae occurred from the middle Pleistocene to the early–middle Pleistocene transition when it became locally extinct. After a long absence of...

We develop statistical methods for a comparison of two, potentially unevenly sampled time series covering the same period of time. The differences in the time series are analyzed in several time resolutions or scales. A difference is flagged for a given scale and time point if the slopes of the two time series are found to be significantly differen...

August Sea Surface Temperatures (aSSTs) based on fossil diatom assemblages are generated from a 230-year-long sediment core (Rapid 21-12B), from the southern limb of the Gardar Drift on the eastern flank of the Reykjanes Ridge in the subpolar North Atlantic. The reconstructed record has two years average resolution and represents the highest resolu...

Sea surfaces temperatures (SSTs) are generated from a 1000-year-long sediment core from the eastern flank of Reykjanes Ridge in the subpolar North Atlantic with a time resolution of 2-10 years. 54.3 cm long box core (Rapid 21-12B) and 370 cm long gravity core (RAPID 21-3K) were recovered from deep-sea sediments (2630 m water depth) during the RRS C...

The Hitura open pit exposes a sedimentary sequence up to 50 m thick representing Late Saalian to Holocene glacial and non-glacial sediments. The sequence was investigated using sedimentological methods, OSL-dating and pollen and diatom analyses to reconstruct the Middle Weichselian (MWG) glacial event in the central part of the Scandinavian Ice She...

The ‘Antrea Net Find’, found in 1913 in Korpilahti on the Karelian Isthmus, is one of the most important archaeological discoveries in Finland. For a long time, it was the oldest dated net find in Europe. New sediment samples were taken from the assumed find spot in 1998. The original net material and the new sediment sequence around the find spo...

The palaeoenvironment of the Karelian Isthmus area during the Litorina Sea stage of the Baltic Sea history, between 8.0 and 4.5 kyr BP (8.8-5.2 cal. kyr BP), was reconstructed by studying four sites located on the Karelian Isthmus in Russia. Methods included diatom and pollen analyses, sediment lithostratigraphical interpretation and 14C dating. Th...

Lake isolation studies provide a reliable method for reconstructing the sea-level history of areas affected by the glacio-isostatic land uplift. In this study, Late Holocene relative sea-level changes were investigated along the southern coast of Finland, Gulf of Finland in the Baltic Sea, by studying 11 isolation basins in four areas (Kirkkonummi,...

The Mommark sequence represents a nearly complete record of sedimentation in the Eemian (MIS 5e), and the diatom succession covers almost the entire interglacial. A floating chronology of the deposits is based on correlation of the local pollen stratigraphy with annually laminated sequences in northern Germany. The diatom succession starts with a s...

Several Eemian (Mikulino) marine deposits are known from the northwestern part of Russia and from Estonia. The best-known deposits are situated at Mga, Russia and at Prangli, Estonia. Two new sites with clayey and silty deposits covered by till were studied for pollen and diatoms at Peski, Russia and Põhja-Uhtju, Estonia. At Peski, the deposit repr...

Shoreline displacement in the eastern part of the Gulf of Finland during the past 9000 radiocarbon years was reconstructed by studying a total of 10 isolated lake and mire basins located in Virolahti in southeastern Finland and on the Karelian Isthmus, and in Ingermanland in Russia. Study methods were diatom analyses, sediment lithostratigraphical...

Lake Vh-Pitkusta is a 35-m deep meromictic kettle-hole lake in SW Finland. The topmost 15cm of the sediment stratigraphy consists of black gyttja, representing the last ca. 600years. A sediment core from the deepest point was examined with multi-proxy methods to determine the origin and evolution of the basin, the onset of the meromictic conditions...

Several relatively well-preserved last interglacial (Eemian, marine oxygen isotope substage 5e; ca. 130–116 ka) deposits containing marine diatom flora have been found in Finland. In addition to these Finnish sites, more numerous Eemian (Mikulino) marine deposits are known from the northwestern part of Russia and from Estonia. Two new clayey and si...

A sediment core from Lake Saarasjarvi at 19.5 m a.s.l. in Virolahti near the coast of the Gulf of Finland, SE Finland, was studied for lithology and diatom stratigraphy. The core records changes in the Baltic relative sea level over the last 8000 years. The basin was first isolated from the Baltic slightly before 8000 yrs BP as a result of the rapi...