Bennet JuhlsAlfred Wegener Institute Helmholtz Centre for Polar and Marine Research | AWI · Department of Permafrost Research
Bennet Juhls
Master of Science
About
33
Publications
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316
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Introduction
Bennet Juhls currently works at the Institute of Space Sciences, Freie Universität Berlin. Bennet does research in biogeochemistry in Arctic River, coastal and shelf water using in situ observations and Ocean Color Remote Sensing
Additional affiliations
August 2020 - April 2021
Publications
Publications (33)
Increasing air temperatures and associated permafrost thaw in Arctic river watersheds, such as the Mackenzie River catchment, are directly affecting the aquatic environment. As a consequence, the quantity and the quality of dissolved organic carbon (DOC) that is transported via the Mackenzie River into the Arctic Ocean is expected to change. Partic...
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...
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...
The Lena Delta in Siberia is the largest delta in the Arctic and as a snow-dominated ecosystem particularly vulnerable to climate change. Using the two decades of MODerate resolution Imaging Spectroradiometer (MODIS) satellite acquisitions, this study investigates interannual and spatial variability of snow-cover duration and summer vegetation vita...
Arctic river deltas define the interface between the terrestrial Arctic and the Arctic Ocean. They discharge sediments, nutrients, and soil organic carbon to the Arctic Ocean and provide key stratigraphic records of permafrost landscape evolution. As the climate warms, the future evolution of Arctic deltas will likely take a different course, with...
Climate warming and related drivers of soil thermal change in the Arctic are expected to modify the distribution and dynamics of carbon contained in perennially frozen grounds. Thawing of permafrost in the Mackenzie Delta region of northwestern Canada, coupled with increases in river discharge and coastal erosion, trigger the release of terrestrial...
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...
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...
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...
The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water colum...
The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water colum...
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 assessing impacts o...
We combine satellite data products to provide a first and general overview
of the physical sea ice conditions along the drift of the international Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition and a comparison with previous years (2005–2006 to 2018–2019). We find that the MOSAiC drift was around 20 % fas...
Arctic deltas and their river channels are characterized by three components of the cryosphere: snow, river ice, and permafrost, making them especially sensitive to ongoing climate change. Thinning river ice and rising river water temperatures may affect the thermal state of permafrost beneath the riverbed, with consequences for delta hydrology, er...
Permafrost degradation in the catchment of major Siberian rivers, combined with higher precipitation in a warming climate, could increase the flux of terrestrially derived dissolved organic matter (tDOM) into the Arctic Ocean (AO). Each year, ∼ 7.9 Tg of dissolved organic carbon (DOC) is discharged into the AO via the three largest rivers that flow...
We combine satellite data products to provide a first and general overview of the sea-ice conditions along the MOSAiC drift and a comparison with previous years. We find that the MOSAiC drift was around 25 % faster than the climatological mean drift, as a consequence of large-scale low-pressure anomalies prevailing around the Barents-Kara-Laptev Se...
Arctic regions and their water bodies are affected by a rapidly warming
climate. Arctic lakes and small ponds are known to act as an important
source of atmospheric methane.
However, not much is known about other types of water bodies in permafrost
regions, which include major rivers and coastal bays as a transition type
between freshwater and mari...
Remobilization of soil carbon as a result of permafrost degradation in the drainage basin of the major Siberian rivers combined with higher precipitation in a warming climate potentially increase the flux of terrestrial derived dissolved organic matter (tDOM) into the Arctic Ocean. The Laptev (LS) and East Siberian Seas (ESS) receive enormous amoun...
Warming air temperatures, shifting hydrological regimes and accelerating permafrost thaw in the catchments of the Arctic rivers is affecting their biogeochemistry. Arctic river monitoring is necessary to observe changes in the mobilization of dissolved organic matter (DOM) from permafrost. The Lena River is the second largest Arctic river and 71% o...
Abstract. Arctic regions and their water bodies are being affected by the most rapid climate warming on Earth. Arctic lakes and small ponds are known to act as an important source of atmospheric methane. However, not much is known about other types of water bodies in permafrost regions, which include major rivers and coastal bays as a transition ty...
Climate change is affecting the rate of carbon cycling, particularly in the Arctic. Permafrost degradation through deeper thaw and physical disturbances results in the release of carbon dioxide and methane to the atmosphere and to an increase in lateral dissolved organic matter (DOM) fluxes. Whereas riverine DOM fluxes of the large Arctic rivers ar...
River water is the main source of dissolved organic carbon (DOC) in the Arctic Ocean. DOC plays an important role in the Arctic carbon cycle, and its export from land to sea is expected to increase as ongoing climate change accelerates permafrost thaw. However, transport pathways and transformation of DOC in the land-to-ocean transition are mostly...
Offshore permafrost plays a role in the global climate system, but observations of permafrost thickness, state, and composition are limited to specific regions. The current global permafrost map shows potential offshore permafrost distribution based on bathymetry and global sea level rise. As a first‐order estimate, we employ a heat transfer model...
River water is the main source of dissolved organic carbon (DOC) in the Arctic Ocean. DOC plays an important role in the Arctic carbon cycle and its export from land to sea is expected to increase as ongoing climate change accelerates permafrost thaw. However, transport pathways and transformation of DOC in the land-to-ocean transition are mostly u...
Climate change is an important control of carbon cycling, particularly in the Arctic. Permafrost degradation through deeper thaw and physical disturbances result in the release of carbon dioxide and methane to the atmosphere and to an increase in riverine dissolved organic matter (DOM) fluxes. Whereas riverine DOM fluxes of the large Arctic rivers...
The Laptev and Eastern Siberian shelves are the world’s broadest shallow shelf systems. Large Siberian rivers and coastal erosion of up to meters per summer deliver large volumes of terrestrial matter into the Arctic shelf seas. In this chapter we investigate the applicability of Ocean Colour Remote Sensing during the ice-free summer season in the...
Waterbodies in the arctic permafrost zone are considered a major source of the greenhouse gas methane (CH4) in addition to CH4 emissions from arctic wetlands. However, the spatio‐temporal variability of CH4 fluxes from waterbodies complicates spatial extrapolation of CH4 measurements from single waterbodies. Therefore, their contribution to the CH4...
A multiyear mooring record (2007–2014) and satellite imagery highlight the strong temperature variability and unique hydrographic nature of the Laptev Sea. This Arctic shelf is a key region for river discharge and sea ice formation and export and includes submarine permafrost and methane deposits, which emphasizes the need to understand the thermal...
Projects
Projects (5)
Most human activity in the Arctic takes place along permafrost coasts. Climate change and permafrost thaw is exposing these coasts to rapid change, change that threatens the rich biodiversity, puts pressure on communities and contributes to the vulnerability of the global climate system. The Nunataryuk programme aims to better understand: 1. what happens to the fluxes and organic matter released from thawing coastal and subsea permafrost; 2. what risks are posed by thawing coastal permafrost to infrastructure, indigenous and local communities and people’s health; 3. what are the long-term impacts of permafrost thaw on global climate and the economy.
Dramatically rising temperatures in the Arctic and consequent thaw of permafrost soils lead to a growing exposure of organic matter (OM)
and its carbon (OC) to the hydrological cycle and increasing fluxes from rivers to the Arctic Ocean. Declining sea ice extent and shorter icecover period open new pathways for OC transport that may boost climate change positive feedback mechanisms. For example, increasing
OM in surface water enhances radiative warming, which accelerates sea ice melt, which, in turn, opens new pathways for OC transport. OC,
mobilized from thawing permafrost, affects the global carbon cycle at an unquantified level. We propose to use a number of CCI Essential
Climate Variables (ECV) to quantify and monitor changes in OM and OC runoff and identify its controlling mechanisms. CCI Ocean Colour
products will be used to quantify total riverine OC flux to the Arctic Ocean and monitor its pathways and fate. These data will be used to
predict future trends in land-ocean OC transport. Ocean Colour Remote Sensing algorithms for the retrieval of OC concentration were
recently evaluated in the Mackenzie and Lena River mouth regions (Juhls et al., 2019; Juhls et al, in prep.). They will be merged with
ongoing in situ sampling of Arctic rivers (e.g. Juhls et al., 2020) to provide the first pan-Arctic long-term estimates of particulate and dissolved
OC flux into the Arctic Ocean. Permafrost distribution and its thermal state (CCI Permafrost), snow cover (CCI Snow Cover), and land
surface temperature (CCI Land Surface Temperature) will reveal terrestrial drivers for long-term flux trends and their inter-annual variations
over the same period. Sea surface temperature and salinity (CCI SST and CCI Sea Surface Salinity) and sea ice concentration (CCI Sea
Ice) will reveal implications for the Arctic Ocean. This project will bring together multiple CCI data across the coastal divide to show linkages
between land and marine responses to climate change.
CACOON will quantify the effect of changing freshwater export and terrestrial permafrost thaw on the type and fate of river-borne organic matter (OM) delivered to Arctic coastal waters, and resultant changes on ecosystem functioning in the coastal AO. We will achieve this though a combined observational, experimental and modelling study. We will conduct laboratory experiments to parameterise the susceptibility of terrigenous carbon to abiotic and biotic transformation and losses, then use the results from these to deliver a marine ecosystem model capable of representing the major biogeochemical cycles of carbon, nutrients and OM cycling in these regions. We will apply this model to assess how future changes to freshwater runoff and terrigenous carbon fluxes alter the biogeochemical structure and function of shelf ecosystems.
generate novel seasonally-explicit datasets of OM source and transformation across the Kolyma and Lena River nearshore environments
identify and parameterise key abiotic and biotic processes affecting terrestrial organic matter fluxes from land-to-ocean
deliver projections of how future changes to freshwater runoff and terrestrial organic matter fluxes will alter the biogeochemical structure and function of shelf ecosystems.
Field campaigns on the Lena will be co-ordinated by Dr Jens Strauss (Alfred Wegener Institute, Germany), and by Dr Paul Mann (Northumbria University, UK) on the Kolyma River. Additional sample analysis and data will be obtained by a range of international project partners in Germany, UK, USA, Russia and Norway.
https://www.changing-arctic-ocean.ac.uk/project/cacoon/
