Jens Strauss

Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research | AWI · Department of Permafrost Research

Estimates for circumpolar permafrost organic carbon (OC) storage suggest that this pool contains twice the amount of current atmospheric carbon. The Yedoma region sequestered substantial quantities of OC and is unique because its deep OC was incorporated into permafrost during Ice-Age conditions. Rapid inclusion of labile organic matter into permaf...

Permafrost is a distinct feature of the terrestrial Arctic and is vulnerable to climate warming. Permafrost degrades in different ways, including deepening of a seasonally unfrozen surface and localized but rapid development of deep thaw features. Pleistocene ice-rich permafrost with syngenetic ice-wedges, termed Yedoma deposits, are widespread in...

Ice-rich permafrost in the circum-Arctic and sub-Arctic (hereafter pan-Arctic), such as late Pleistocene Yedoma, are especially prone to degradation due to climate change or human activity. When Yedoma deposits thaw, large amounts of frozen organic matter and biogeochemically relevant elements return into current biogeochemical cycles. This mobiliz...

Nitrogen regulates multiple aspects of the permafrost climate feedback, including plant growth, organic matter decomposition, and the production of the potent greenhouse gas nitrous oxide. Despite its importance, current estimates of permafrost nitrogen are highly uncertain. Here, we compiled a dataset of >2000 samples to quantify nitrogen stocks i...

Permafrost regions, characterised by extensive belowground excess ice, are highly vulnerable to rapid thaw, particularly in areas such as the Yedoma domain. This region is known to freeze-lock a globally significant stock of soil nitrogen (N). However, the fate of this N upon permafrost thaw remains largely unknown. In this study, we assess the imp...

Climate warming in the Arctic results in thawing permafrost and associated processes like thermokarst, especially in ice-rich permafrost regions. Since permafrost soils are one of the largest organic carbon reservoirs of the world, their thawing could lead to the release of greenhouse gases, further exacerbating climate warming. To enhance predicti...

Climate warming in the Arctic is directly connected to rising sea levels and increasing erosion of permafrost coasts, leading to inland migrating coastlines and the transformation of coastal permafrost lakes into thermokarst lagoons. These lagoons represent transitional zones between terrestrial to subsea permafrost environments. So far, the effect...

This study investigates the impact of large herbivores on soil organic matter (OM) stability in Arctic permafrost and seasonally frozen ground ecosystems, focusing on the potential preservation effect of grazing. Soil samples were collected from Siberian and Finnish permafrost and non-permafrost areas and organic carbon content, carbon-to-nitrogen...

Arctic permafrost coasts, affected by rising sea levels and increasing coastal erosion in a warming climate, undergo significant changes. Simulating how permafrost is impacted by inundation with fresh, brackish and marine water enhances our understanding of permafrost carbon stock responses to increasingly marine conditions. We investigated CO 2 an...

Permafrost soils—perennially frozen ground and overlying thin seasonally unfrozen layer soils that contain a large portion of the global soil carbon—were long known as a protective feature for decomposable organic material. With ongoing climate warming, these deposits are thawing rapidly, creating both local and global challenges. Local ground coll...

Lake ecosystems are affected globally by climate warming and anthropogenic influences. However, impacts on boreal lake ecosystems in Siberia, remain largely underexplored. Our aim is to determine if shifts in diatom assemblages in a remote lake in eastern Siberia are related to climate warming, similar to observations in temperate regions, while al...

The Arctic is experiencing rapid warming, which among other processes results in increasing erosion of coastal permafrost and the release of ancient organic carbon (OC) into the Arctic Ocean, which in turn might result in greenhouse gas emissions following its decomposition. Supply of terrigenous organic matter to the ocean affects near‐shore nutri...

Organic carbon (OC) in permafrost interacts with the mineral fraction of soil and sediments, representing < 1% to ~80% of the total OC pool. Quantifying the nature and controls of mineral-OC interactions is therefore crucial for realistic assessments of permafrost-carbon-climate feedbacks, especially in ice-rich regions facing rapid thaw and the de...

Permafrost-agroecosystems include all cultivation and pastoral activities in areas underlain by permafrost. These systems support local livelihoods and food production and are rarely considered in global agricultural studies but may become more relevant as climate change is increasing opportunities for food production in high latitude and mountaino...

As global temperatures continue to rise, a key uncertainty of terrestrial carbon (C)–climate feedback is the rate of C loss upon abrupt permafrost thaw. This type of thawing—termed thermokarst—may in turn accelerate or dampen the response of microbial degradation of soil organic matter and carbon dioxide (CO2) release to climate warming. However, s...

Thermokarst lagoons form at the terrestrial-marine interface when thermokarst lakes, hotspots for Arctic methane emissions, erode into the ocean. These lagoons are dynamic environments with seasonal ice build-up and potential alternations between freshwater and marine discharge and make an excellent natural laboratory for studying methane cycling c...

Northern latitudes have been significantly impacted by recent climate warming, which has increased the probability of experiencing extreme weather events. To comprehensively understand hydroclimate change and reconstruct hydroclimatic anomalies such as drought periods, appropriate proxy records reaching further back in time beyond meteorological me...

Wetlands in Arctic drained lake basins (DLB) have a high potential for carbon storage in vegetation and peat as well as for elevated greenhouse gas emissions. However, the evolution of vegetation and organic matter is rarely studied in DLBs, making these abundant wetlands especially uncertain elements of the permafrost carbon budget. We surveyed mu...

Climatic warming is predicted to affect high-latitude habitats, such as boreal peatlands, at a larger magnitude than the global average. The controls on the breakdown of organic matter in peatlands are complex; it’s unclear how climatic warming will affect the stability of the large carbon pool that’s currently stored in peatlands. To investigate t...

Significant progress in permafrost carbon science made over the past decades include the identification of vast permafrost carbon stocks, the development of new pan‐Arctic permafrost maps, an increase in terrestrial measurement sites for CO2 and methane fluxes, and important factors affecting carbon cycling, including vegetation changes, periods of...

Several studies investigated changes in microbial community composition in thawing permafrost landscapes, but microbial assemblages in the transient ecosystems of the Arctic coastline remain poorly understood. Thermokarst lakes, abrupt permafrost thaw features, are widespread along the pan-Arctic coast and transform into thermokarst lagoons upon co...

Climate change forces rapid and extreme changes in coastal permafrost regions such as permafrost thaw, sea-level rise and increased frequencies of storm surges. In order to deepen the understanding of these changes on potential carbon dioxid (CO2) and methane (CH4) production, this study conducted an anaerobic incubation to mimic sea water inundati...

The availability of silicon (Si) in the ocean plays an important role in regulating biogeochemical and ecological processes. The Si budget of the Arctic Ocean appears balanced, with inputs equivalent to outputs, though it is unclear how a changing climate might aggravate this balance. In this study, we focus on Si cycling in Arctic coastal areas an...

This chapter synthesizes information about the storage and vulnerability of organic matter in permafrost. The permafrost region is rapidly warming, leading to degradation and release of carbon. Permafrost holds a vast amount of organic carbon (~1460–1600 gigatons (Gt = 10^9 t = 10^12 kg) on land, and in total more than 4300 Gt (including organic ca...

Northern latitudes have been significantly impacted by recent climate warming, which has increased the probability of experiencing extreme weather events. To comprehensively understand hydroclimate change and reconstruct extreme events such as droughts or floods, appropriate proxy records reaching further back in time are needed beyond meteorologic...

To test the effect of reindeer husbandry on soil carbon storage of seasonally frozen ground, we analysed soil and vegetation properties in peatlands and mixed pine and mountain birch forests. We analysed sites with no grazing and contrasting intensities of grazing, and associated trampling, in Northern Finland. With a pilot study approach, we optim...

Permafrost-agroecosystems are highly heterogenous socio-ecological systems that include animal husbandry practices (such as reindeer and yak herding) and crop cultivation in areas that contain permafrost. These systems affect food security, culture and livelihoods and are particularly sensitive to permafrost degradation processes, surface stability...

Permafrost degradation and organic matter decomposition in the terrestrial Arctic are strongly depending on soil temperature throughout the year. These temperatures are affected in numerous ways by activity of large herbivorous animals. We identified snow compaction and animal-induced vegetation changes as key elements. Therefore, we analysed soil...

Subsea permafrost carbon pools below the Arctic shelf seas are a major unknown in the global carbon cycle. We combine a numerical model of sedimentation and permafrost evolution with simplified carbon turnover to estimate accumulation and microbial decomposition of organic matter on the pan-Arctic shelf over the past four glacial cycles. We find th...

This study is based on multiproxy data gained from a 14C-dated 6.5 m long sediment core and a 210Pb-dated 23 cm short core retrieved from Lake Rauchuagytgyn in Chukotka, Arctic Russia. Our main objectives are to reconstruct the environmental history and ecological development of the lake during the last 29 kyr and to investigate the main drivers be...

Rapid Arctic warming accelerates permafrost thaw, causing an additional release of terrestrial organic matter (OM) into rivers and, ultimately, after transport via deltas and estuaries, to the Arctic Ocean nearshore. The majority of our understanding of nearshore OM dynamics and fate has been developed from freshwater rivers despite the likely impa...

Interactions between minerals and organic carbon (OC) in soils are key to stabilize OC and mitigate greenhouse gas emissions upon permafrost thaw. However, changes in soil water pathways upon permafrost thaw are likely to affect the stability of mineral OC interactions by inducing their dissolution and precipitation. This study aims to assess and q...

Arctic soils store large amounts of organic carbon and other elements, such as amorphous silicon, silicon, calcium, iron, aluminum, and phosphorous. Global warming is projected to be most pronounced in the Arctic, leading to thawing permafrost which, in turn, changes the soil element availability. To project how biogeochemical cycling in Arctic eco...

Thermokarst lagoons represent the transition state from a freshwater lacustrine to a marine environment, and receive little attention regarding their role for greenhouse gas production and release in Arctic permafrost landscapes. We studied the fate of methane (CH4 ) in sediments of a thermokarst lagoon in comparison to two thermokarst lakes on the...

One quarter of the Northern hemisphere is underlain by permanently frozen ground, referred to as permafrost. Due to climate warming, irreversibly thawing permafrost is releasing organic matter frozen for up to a million years, most of which decomposes into carbon dioxide and methane, further enhancing the greenhouse effect. Part of this organic mat...

Rapid Arctic environmental change affects the entire Earth system as thawing permafrost ecosystems release greenhouse gases to the atmosphere. Understanding how much permafrost carbon will be released, over what time frame, and what the relative emissions of carbon dioxide and methane will be is key for understanding the impact on global climate. I...

This study is based on multiproxy data gained from a 14C-dated 6.5 m long sediment core and a 210Pb-dated 23 cm short core retrieved from Lake Rauchuagytgyn in Chukotka, Arctic Russia. The main objectives are to reconstruct the environmental history and ecological development of the lake during the last 29k years and to investigate the main drivers...

Rapid Arctic warming accelerates permafrost thaw, causing an additional release of terrestrial organic matter (OM) 15 into rivers, and ultimately, after transport via deltas and estuaries, to the Arctic Ocean nearshore. The majority of our understanding of nearshore OM dynamics and fate has been developed from freshwater rivers, despite the likely...

The Batagay megaslump, a permafrost thaw feature in north-eastern Siberia, provides access to ancient permafrost up to ∼650 kyr old. We aimed to assess the permafrost-locked organic matter (OM) quality and to deduce palaeo-environmental information on glacial–interglacial timescales. We sampled five stratigraphic units exposed on the 55 m high slum...

Arctic shelf seas receive greater quantities of river runoff than any other ocean region and are experiencing increased freshwater loads and associated terrestrial matter inputs since recent decades. Amplified terrestrial permafrost thaw and coastal erosion is exposing previously frozen organic matter, enhancing its mobilization and release to near...

Arctic warming and permafrost thaw visibly expose changes in the landscape of the Lena River delta, the largest Arctic delta. Determining the past and modern river regime of thick deltaic deposits shaping the Lena River mouth in north‐eastern Siberia is critical for understanding the history of delta formation and carbon sequestration. Using a 65 m...

The risk of carbon emissions from permafrost is linked to an increase in ground temperature and thus in particular to thermal insulation by vegetation, soil layers and snow cover. Ground insulation can be influenced by the presence of large herbivores browsing for food in both winter and summer. In this study, we examine the potential impact of lar...

This outreach poster on fieldwork at Elson Lagoon and the Teshekpuk Lake Observatory, carried out by a team from the Alfred Wegener Institute, gives an overview of the field methods used to study thermokarst lagoon formation and the carbon cycle at the frontier between terrestrial and subsea permafrost.

Arctic soils store large amounts of organic carbon and other elements such as amorphous silica, silicon, calcium, iron, aluminium, and phosphorous. Global warming is projected to be most pronounced in the Arctic leading to thawing permafrost, which in turn is changing the soil element availability. To project how biogeochemical cycling in Arctic ec...

The stabilizing properties of mineral–organic carbon (OC) interactions have been studied in many soil environments (temperate soils, podzol lateritic soils, and paddy soils). Recently, interest in their role in permafrost regions is increasing as permafrost was identified as a hotspot of change. In thawing ice‐rich permafrost regions, such as the Y...

Climate change is an existential threat to the vast global permafrost domain. The diverse human cultures, ecological communities, and biogeochemical cycles of this tenth of the planet depend on the persistence of frozen conditions. The complexity, immensity, and remoteness of permafrost ecosystems make it difficult to grasp how quickly things are c...

Thermokarst lagoons represent the transition state from a freshwater lacustrine to a marine environment, and receive little attention regarding their role for greenhouse gas production and release in Arctic permafrost landscapes. We studied the fate of methane (CH 4 ) in sediments of a thermokarst lagoon in comparison to two thermokarst lakes on th...

Arctic river deltas and deltaic near-shore zones represent important land–ocean transition zones influencing sediment dynamics and nutrient fluxes from permafrost-affected terrestrial ecosystems into the coastal Arctic Ocean. To accurately model fluvial carbon and freshwater export from rapidly changing river catchments as well as assess impacts of...

Organic carbon (OC) stored in Arctic permafrost represents one of Earth's largest and most vulnerable terrestrial carbon pools. Amplified climate warming across the Arctic results in widespread permafrost thaw. Permafrost deposits exposed at river cliffs and coasts are particularly susceptible to thawing processes. Accelerating erosion of terrestri...

In the context of global warming, the melting of arctic permafrost raises the threat of a re-emergence of microorganisms some of which were shown to remain viable in ancient frozen soils for up to half a million years. In order to evaluate this risk, it is of interest to acquire a better knowledge of the composition of the microbial communities fou...

The Batagay megaslump, a permafrost thaw feature in northeastern Siberia, provides access to ancient permafrost up to ~650 ka old. We aimed to assess the permafrost-locked organic matter (OM) quality and to deduce paleoenvironmental information on glacial-interglacial timescales. We sampled five stratigraphic units exposed on the 55-m-high slump he...

Since the discovery of frozen megafauna carcasses in Northern Siberia and Alaska in the early 1800s, the Yedoma phenomenon has attracted many Arctic explorers and scientists. Exposed along coastal and riverbank bluffs, Yedoma often appears as large masses of ice with some inclusions of sediment. The ground ice particularly mystified geologists and...

The Arctic is nutrient limited, particularly by nitrogen, and is impacted by anthropogenic global warming which occurs approximately twice as fast compared to the global average. Arctic warming intensifies thawing of permafrost-affected soils releasing their large organic nitrogen reservoir. This organic nitrogen reaches hydrological systems, is re...

Organic carbon (OC) stored in Arctic permafrost represents one of Earth’s largest and most vulnerable terrestrial carbon pools. Amplified climate warming across the Arctic results in widespread permafrost thaw. Permafrost deposits exposed at river cliffs and coasts are particularly susceptible to thawing processes. Accelerating erosion of terrestri...

Arctic warming is causing ancient perennially frozen ground (permafrost) to thaw, resulting in ground collapse, and reshaping of landscapes. This threatens Arctic peoples' infrastructure, cultural sites, and land-based natural resources. Terrestrial permafrost thaw and ongoing intensification of hydrological cycles also enhance the amount and alter...

Cryogenic weathering is a key driver of periglacial sediment composition and properties. Selective mineral-grain weathering caused by freeze-thaw cycles in permafrost environments has the ability to dominate this process, leading to silt-rich grain-size distributions. The cryogenic weathering index (CWI) is a promising tool to quantify cryogenic we...

Thermokarst lagoons, forming when thermokarst lakes are inundated by the sea, are an transition stage where terrestrial permafrost is introduced into the subsea realm. Here, permafrost and lacustrine carbon pools are transformed along Arctic coasts. During thaw previously frozen organic carbon can be converted into the greenhouse gases (GHG) carbon...

With an increasingly warm Arctic, new challenges arise as Arctic permafrost ground starts to thaw further. Thaw destabilizes the ground and makes soil-stored organic carbon available for microbial decomposition. To reduce thaw intensity, we examined the impact of large herbivorous animals thaw depth in the seasonal active layer and carbon storage i...