scholarly journals Small waterbodies reduce the carbon sink of a polygonal tundra landscape

2021 ◽  
Author(s):  
Lutz Beckebanze ◽  
Zoé Rehder ◽  
David Holl ◽  
Charlotta Mirbach ◽  
Christian Wille ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Budget ◽  
Carbon Sink ◽  
Open Water ◽  
Methane Emissions ◽  
The Arctic ◽  
Sink Strength ◽  
Small Waterbodies ◽  
Methane Fluxes ◽  
The Impact

Abstract. Arctic permafrost landscapes have functioned as a global carbon sink for millennia. These landscapes are very heterogeneous, and the omnipresent waterbodies are a carbon source within them. Yet, only a few studies focus on the impact of these waterbodies on the landscape carbon budget. We compare carbon dioxide and methane fluxes from small waterbodies to fluxes from the surrounding tundra using eddy covariance measurements from a tower located between a large pond and semi-terrestrial vegetated tundra. When taking the open-water areas of small waterbodies into account, the carbon dioxide sink strength of the landscape was reduced by 11 %. While open-water methane emissions were similar to the tundra emissions, some parts of the studied pond's shoreline exhibited much higher emissions, underlining the high spatial variability of methane emissions. We conclude that gas fluxes from small waterbodies can contribute significantly to the carbon budget of arctic tundra landscapes. Consequently, changes in arctic hydrology and the concomitant changes in the waterbody distribution may substantially impact the overall carbon budget of the Arctic.

scholarly journals The carbon budget of a tundra in the north-eastern Russian Arctic during the snow free season and its stability in the 2003-2016 period

2020 ◽  
Author(s):  
Han Dolman ◽  
Jacobus van Huissteden ◽  
Joshua Dean ◽  
Trofim Maximov ◽  
Roman Petrov ◽  
...  
Keyword(s):  
Climate Warming ◽  
Carbon Budget ◽  
Carbon Sink ◽  
The Arctic ◽  
Permafrost Degradation ◽  
Annual Variability ◽  
Tundra Ecosystem ◽  
North Eastern ◽  
Climatic Drivers ◽  
The Impact

<p>Large quantities of carbon are stored in the terrestrial permafrost of the Arctic region where the rate of climate warming is two to three times more than the global mean and the largest temperature anomalies observed in autumn and winter. The quantification of the impact of climate warming on the degradation of permafrost and the associated potential release to the atmosphere of carbon stocked in the soil in the form of greenhouse gases, thus further increasing the radiative forcing of the atmosphere, is a research priority in the field of biogeosciences. Land-atmosphere turbulent fluxes of CO<sub>2</sub> and CH<sub>4</sub> have been monitored at the tundra site of Kytalyk in north-eastern Siberia (70,82 N; 147.48 E) by means of eddy covariance since 2003 and 2008, respectively; regular measurement campaigns have been carried out since then. Here we present results of the seasonal CO<sub>2</sub> budget of the tundra ecosystem for the 2003-2016 period based on observations encompassing the permafrost thawing season and analyze the inter-annual differences in the seasonal patterns of CO<sub>2</sub> fluxes considering the separate the contribution of climatic drivers and ecosystem functional parameters relative to the processes of respiration and photosynthesis. The variability of the CO<sub>2</sub> budget is also discussed in view of the impact of the timing and length of the snow free period.</p><p>The Kytalyk tundra acted as an atmospheric carbon dioxide sink with relatively small inter-annual variability (-96.1±11.9 gC m<sup>-2</sup>) during the snow free season and the seasonal CO<sub>2</sub> budget did not show any trend over time. The pronounced meteorological variability characterizing Arctic summers was a key factor in shaping the length of the carbon uptake period, which did not progressively increased despite its tendency to start earlier, and in determining the magnitude of CO<sub>2</sub> fluxes. No clear evidence of inter-annual changes in the eco-physiological response parameters of CO<sub>2</sub> fluxes to climatic drivers (global radiation and air temperature) was found along the course of the analysed period. Methane fluxes had a minor contribution to the carbon budget of the snow-free season representing on average an emission of 3.2 gC m<sup>-2</sup> (2008-2016) with apparently small inter-annual variability. Similarly, the size of the carbon exported laterally from the ecosystem in the form of dissolved organic carbon flux amounted to 3.1 gC m<sup>-2</sup> as determined experimentally. After including these last terms in the budget, the magnitude of the carbon sink associated with the net ecosystem productivity is reduced by 6%, while the GHG budget still denotes a sink of -60.4 ± 11.9 gC-CO<sub>2</sub>eq (methane GWP over 100-year time horizon).</p><p>The monitored tundra was to date exerting a steady climate warming mitigation effect as far as the snow free season is concerned, however the figure of its carbon sink could be potentially sensibly lower due to overlooked emissions in the autumn freeze-up and early winter periods. Also, nonlinear accelerations in the permafrost degradation could happen once tipping points in the Arctic climate are exceeded. Both aspects underline the relevance of long term and continuous biogeochemical monitoring in permafrost tundra environments.</p>

Eddy covariance flux measurements of momentum, heat and carbon dioxide in Hudson Bay at the onset of sea ice melt 

2021 ◽  
Author(s):  
Richard Sims ◽  
Brian Butterworth ◽  
Tim Papakyriakou ◽  
Mohamed Ahmed ◽  
Brent Else
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Sea Ice ◽  
Eddy Covariance ◽  
Open Water ◽  
The Arctic ◽  
Gas Transfer ◽  
Hudson Bay ◽  
Flux Measurements ◽  
Ice Fraction

<p>Remoteness and tough conditions have made the Arctic Ocean historically difficult to access; until recently this has resulted in an undersampling of trace gas and gas exchange measurements. The seasonal cycle of sea ice completely transforms the air sea interface and the dynamics of gas exchange. To make estimates of gas exchange in the presence of sea ice, sea ice fraction is frequently used to scale open water gas transfer parametrisations. It remains unclear whether this scaling is appropriate for all sea ice regions. Ship based eddy covariance measurements were made in Hudson Bay during the summer of 2018 from the icebreaker CCGS Amundsen. We will present fluxes of carbon dioxide (CO<sub>2</sub>), heat and momentum and will show how they change around the Hudson Bay polynya under varying sea ice conditions. We will explore how these fluxes change with wind speed and sea ice fraction. As freshwater stratification was encountered during the cruise, we will compare our measurements with other recent eddy covariance flux measurements made from icebreakers and also will compare our turbulent CO<sub>2 </sub>fluxes with bulk fluxes calculated using underway and surface bottle pCO<sub>2</sub> data. </p><p> </p>

scholarly journals Hydroelectric Dams in the Brazilian Amazon as Sources of ‘Greenhouse’ Gases

1995 ◽  
Vol 22 (1) ◽  
pp. 7-19 ◽  
Author(s):  
Philip M. Fearnside
Keyword(s):  
Carbon Dioxide ◽  
Greenhouse Gases ◽  
Forest Biomass ◽  
Open Water ◽  
Brazilian Amazon ◽  
Methane Emissions ◽  
Hydroelectric Dams ◽  
Brazilian Amazonia ◽  
Methane Release ◽  
Gas Fluxes

Existing hydroelectric dams in Brazilian Amazonia emitted about 0.26 million tons of methane and 38 million tons of carbon dioxide in 1990. The methane emissions represent an essentially permanent addition to gas fluxes from the region, rather than a one-time release. The total area of reservoirs planned in the region is about 20 times the area existing in 1990, implying a potential annual methane release of about 5.2 million tons. About 40% of this estimated release is from underwater decay of forest biomass, which is the most uncertain of the components in the calculation. Methane is also released in significant quantities from open water, macrophyte beds, and above-water decay of forest biomass.

scholarly journals Alkaline Mineral Soil Amendment: A Climate Change ‘Stabilization Wedge’?

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2299 ◽  
Author(s):  
Fatima Haque ◽  
Yi Chiang ◽  
Rafael Santos
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Soil Amendment ◽  
Agricultural Soil ◽  
Carbon Sink ◽  
Mineral Soil ◽  
Earth Metal ◽  
Mineral Weathering ◽  
Sequestration Potential ◽  
The Impact

Extreme climate change due to heat-trapping gases, especially carbon dioxide, necessitates its mitigation. In this context, the carbon dioxide sequestration technology of enhanced weathering has for years been investigated, with a possible implementation strategy via alkaline mineral soil amendment being more recently proposed. Candidate materials for enhanced weathering include calcium and magnesium silicates, most notably those belonging to the olivine, pyroxene and serpentine groups of minerals, given their reactivity with CO2 and global availability. When these finely crushed silicate rocks are applied to the soil, the alkaline earth metal cations released during mineral weathering gradually react with carbonate anions and results in the formation of pedogenic carbonates, which, over time, and under the right conditions, can accumulate in the soil. This review paper critically reviews the available literature on alkaline mineral soil amendments and its potential to sequester enough CO2 to be considered a climate change ‘stabilization wedge’. Firstly, evidence of how agricultural soil can serve as a carbon sink in discussed, based on the observed accumulation of inorganic carbon in alkaline mineral-amended soils. Secondly, the impact of alkaline minerals on agricultural soil and crops, and the factors determining the rate of the weathering process are assessed. Lastly, the CO2 sequestration potential via alkaline mineral soil amendment is quantified according to an idealized shrinking core model, which shows that it has the potential to serve as a climate change stabilization wedge.

Towers, Chambers & UAVs: Exploring the drivers of carbon sink strength at a temperate peatland

2020 ◽  
Author(s):  
Gillian Simpson ◽  
Carole Helfter ◽  
Caroline Nichol ◽  
Tom Wade
Keyword(s):  
Vegetation Index ◽  
New Technologies ◽  
Carbon Sink ◽  
Meteorological Data ◽  
Sink Strength ◽  
Spatial And Temporal Scales ◽  
Environmental Controls ◽  
Spatial Coverage ◽  
Normalised Difference Vegetation Index ◽  
The Impact

<p>Peatlands are terrestrial carbon sinks of global significance, storing an estimated one-third of global soil carbon. Net Ecosystem Exchange (NEE) of carbon dioxide (CO<sub>2</sub>) can however vary substantially on seasonal and inter-annual timescales, with some peatlands switching from a sink to a source of CO<sub>2</sub>. Complex and sometimes competing processes, such as meteorology and phenology, regulate a peatland’s net carbon sink strength. Understanding seasonal and inter-annual variability in NEE requires studying these environmental controls at multiple spatial and temporal scales. The role of vegetation in regulating NEE can be particularly difficult to ascertain at the finer timescales (e.g. seasonal) and at sites with abundant plant diversity, non-uniform distribution and complex micro-topography, such as peatlands. Vegetation surveys are traditionally conducted every few years and, because of this, they might not capture the shorter-term variations that can result from meteorological anomalies such as drought. New technologies, such as Unmanned Aerial Vehicles (UAVs), offer novel opportunities to improve the temporal resolution and spatial coverage of traditional vegetation survey approaches. UAVs are a more flexible, often cheaper alternative to satellite products, which can be used to collect data at the sub-centimetre scale. Such high resolution is particularly valuable in peatland environments, which typically display strong heterogeneity at the micro-site level (< 0.5 m). We employ UAV surveys with a Parrot Sequoia multispectral camera to map vegetation and track its phenology using vegetation indices such as the Normalised Difference Vegetation Index (NDVI) over the course of two growing seasons at a temperate Scottish peatland. By combining this multispectral data with in-situ NEE measurements (closed chambers and eddy-covariance) and meteorological data, this project aims to quantify the impact of weather and phenology on carbon balance at the site. An improved understanding of these two drivers of peatland carbon cycling will allow for better prediction of the impact of climate change at the site.</p>

scholarly journals The impact of melt ponds on summertime microwave brightness temperatures and sea ice concentrations

2016 ◽  
Author(s):  
S. Kern ◽  
A. Rösel ◽  
L. T. Pedersen ◽  
N. Ivanova ◽  
R. Saldo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Water Fraction ◽  
Microwave Brightness Temperature ◽  
Ice Melt ◽  
Melt Ponds ◽  
Retrieval Algorithms ◽  
The Impact

Abstract. The sea ice concentration (SIC) derived from satellite microwave brightness temperature (TB) data are known to be less accurate during summer melt conditions – in the Arctic Ocean primarily because of the impact of melt ponds on sea ice. Using data from June to August 2009, we investigate how TBs and SICs vary as a function of the ice surface fraction (ISF) computed from open water fraction and melt pond fraction both derived from satellite optical reflectance data. SIC is computed from TBs using a set of eight different retrieval algorithms and applying a consistent set of tie points. We find that TB values change during sea ice melt non-linearly and not monotonically as a function of ISF for ISF of 50 to 100 %. For derived parameters such as the polarization ratio at 19 GHz the change is monotonic but substantially smaller than theoretically expected. Changes in ice/snow radiometric properties during melt also contribute to the TB changes observed; these contributions are functions of frequency and polarization and have the potential to partly counter-balance the impact of changing ISF on the observed TBs. All investigated SIC retrieval algorithms overestimate ISF when using winter tie points. The overestimation varies among the algorithms as a function of ISF such that the SIC retrieval algorithms could be categorized into two different classes. These reveal a different degree of ISF overestimation at high ISF and an opposite development of ISF over-estimation as ISF decreases. For one class, correlations between SIC and ISF are ≥ 0.85 and the associated linear regression lines suggest an exploitable relationship between SIC and ISF if reliable summer sea ice tie points can be established. This study shows that melt ponds are interpreted as open water by the SIC algorithms, while the concentration of ice between the melt ponds is in general being overestimated. These two effects may cancel each other out and thus produce seemingly correct SIC for the wrong reasons. This cancelling effect will in general only be "correct" at one specific value of MPF. Based on our findings we recommend to not correct SIC algorithms for the impact of melt ponds as this seems to violate physical principles. Users should be aware that the SIC algorithms available at the moment retrieve a combined parameter presented by SIC in winter and ISF in summer.

Seasonal methane and carbon dioxide emissions from the coastal nearshore of the Kolyma river, Siberia.

2021 ◽  
Author(s):  
Juri Palmtag ◽  
Cara Manning ◽  
Michael Bedington ◽  
Matthias Fuchs ◽  
Mathias Göckede ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Arctic Ocean ◽  
Carbon Dioxide Emissions ◽  
Open Water ◽  
The Arctic ◽  
Global Ocean ◽  
Nearshore Zone ◽  
Terrestrial Organic Matter ◽  
The Arctic Ocean ◽  
Kolyma River

<p>Arctic rivers deliver ≈11% of global river discharge into the Arctic Ocean, while this ocean represents only ≈1% of the global ocean volume. Ongoing climate warming across the Arctic, and specifically Siberia, has led to regional-scale changes in precipitation patterns, greater rates of permafrost thaw and active layer deepening, as well as enhanced riverbank and coastal erosion. Combined, these climatic and cryospheric perturbations have already resulted in increased freshwater discharge and changes to constituent loads (e.g. dissolved organic carbon - OC) supplied from land to the Arctic Ocean.</p><p>To date, the majority of studies examining terrestrial organic matter (OM) delivery to the Arctic Ocean have focused almost entirely on freshwater (riverine) or fully-marine environments and been conducted during late summer seasons – often due to logistical constraints. Despite this, an improved understanding of how OC is transformed, mineralised and released during transit through the highly reactive nearshore estuarine environment is critical for examining the fate and influence of terrestrial OM on the Arctic Ocean. Capturing seasonality over the open water period is also necessary to identify current OM fluxes to the ocean vs the atmosphere, and aid in constraining how future changes may modify them.</p><p>Here we focus upon carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) measurements collected during six repeated transects of the Kolyma River and nearshore zone (covering ~120 km) from 2019. Transects spanned almost the entirety of the riverine open water season (June to September). We use these results, in parallel with gas concentrations derived from prior studies, to develop and validate a simple box-model of gas emissions from the nearshore zone.</p><p>Observations and model‐derived output data reveal that more than 50% of the cumulative gross delivery of CH<sub>4</sub> and CO<sub>2</sub> to the coastal ocean occurred during the freshet period with dissolved CH<sub>4</sub> concentrations in surface water reaching 660 Nanomole per liter [nmol/l]. These results demonstrate the relevance of seasonal dynamics and its spatial variability which are needed in order to estimate greenhouse gas fluxes on an annual basis.</p><p>More accurate understanding of land-ocean carbon fluxes in the Arctic is therefore crucial to mitigate the effects of climate change and to support the decisions of policy makers.</p>

The Impact of Air Transportation on Carbon Dioxide, Methane, and Nitrous Oxide Emissions in Pakistan: Evidence from ARDL Modelling Approach

2018 ◽  
Vol 3 (6) ◽  
pp. 7-32 ◽  
Author(s):  
Syeda Anam Hassan ◽  
Misbah Nosheen
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Carbon Dioxide Emissions ◽  
Air Transportation ◽  
Methane Emissions ◽  
Nitrous Oxide Emissions ◽  
Positive Relation ◽  
Long Run ◽  
The Impact ◽  
Bound Test

No one can deny the progression and innovation in the aviation transportation collected at national and international level. But the accountancy of the impact of air transportation on environmental degradation is naive and emerging trend of the current era. The air transportation versus environment is the key contribution to the literature that is solely conducted for Pakistan first time in this context. The objective of this research is to compute the impact of air transportation on carbon dioxide emissions, nitrous emissions and methane emissions separately in the three models by applying ARDL bound test approach during 1990 to 2017. The result depicts significant and positive relation of air transportation (carriage) to carbon dioxide emissions (0.77), nitrous emissions (0.20) and methane emissions (0.38) in long-run. The short-run results infer that the air transportation (passenger) has significantly positive relation to carbon dioxide emissions (0.278), nitrous emissions (0.207), and methane emissions (0.080). The econometric outcomes show the significant and direct relation to transportation (both passenger and cargo) to carbon dioxide, methane, and nitrous oxide emissions in short and long-run. Moreover, per capita GDP, population density, and energy demand also significantly affect the environment showing significant and positive coefficients to all three categories (carbon dioxide, methane, and nitrous oxide) of emission. In case of Pakistan, FDI and trade for this duration didn’t significantly contribute to the CO2, NO2, and methane emissions. Since the last decade the economic issues of Pakistan like terrorism, political instability, energy crises, and poor management along with the worst performance by tertiary sectors have severely hit the economy, and as a result, the FDI and trade sector has tormented in a substantial proportion. Finally, pairwise Granger causation also supports the short and long-run consequences. The outcomes suggested that the fuel-efficient energy use and technological diversification in the transportation sector are essential to mitigate the degrading environmental emissions.

Floodplain forest carbon exchange – a micrometeorological point of view

2020 ◽  
Author(s):  
Natalia Kowalska ◽  
Georg Jocher ◽  
Ladislav Šigut ◽  
Marian Pavelka
Keyword(s):  
Forest Canopy ◽  
Forest Ecosystems ◽  
Carbon Sink ◽  
Forest Carbon ◽  
Floodplain Forest ◽  
Mean Annual Temperature ◽  
Sink Strength ◽  
Spatial And Temporal Variability ◽  
Carbon Exchange ◽  
The Impact

<p>Since the eddy covariance (EC) method became a key method for measurements of the energy and greenhouse gas exchange between ecosystems and the atmosphere, a large number of studies was conducted to understand the mechanisms driving the carbon exchange in forest ecosystems. In recent years, case studies further focused on testing and validating the applicability of the EC technique above forest ecosystems, also assessing the spatial and temporal variability of sub canopy fluxes. These studies led to the conclusion that there is a high probability of overestimating the forest carbon sink strength with EC measurements above the forest canopy only, as these measurements may miss respiration components from within and below the canopy due to insufficient mixing across the canopy. Additional below canopy EC measurements were suggested to tackle this problem and to get information about potential decoupling between below and above forest canopy air masses as well as potentially missing respiration components in the above canopy derived signal.</p><p>The overall goal of the study here is to derive an as detailed as possible understanding of the carbon exchange in Lanžhot floodplain forest with the help of concurrent EC measurements below and above the forest canopy. Lanžhot floodplain forest is situated 6.5 km north of the confluence of the Morava and Thaya rivers in Czech Republic (48.6815483 N, 16.9463317 E). The long-term average annual precipitation at this site is around 517 mm and the mean annual temperature is 9.5 °C. The average groundwater level is -2.7 m. Since a long time flooding occurs here very rarely, the last flooding event was in 2013. In addition, the site is hydrologically managed. Consequently, the water regime of the site changed over the years and represents nowadays relatively dry conditions for such type of ecosystem.</p><p>To reach our research goal we evaluate different single- and two-level filtering strategies of the above canopy derived carbon exchange values and the impact of these filterings on the annual ecosystem carbon exchange rates. Our hypothesis is that conventional single-level EC flux filtering strategies like the u<sub>*</sub>-filtering might not be sufficient to fully capture the carbon exchange of the studied floodplain forest ecosystem. We further hypothesize that additional below canopy EC measurements are mandatory to achieve unbiased forest carbon exchange values with the EC technique.</p>

scholarly journals Arctic regional methane fluxes by ecotope as derived using eddy covariance from a low-flying aircraft

2017 ◽  
Vol 17 (13) ◽  
pp. 8619-8633 ◽  
Author(s):  
David S. Sayres ◽  
Ronald Dobosy ◽  
Claire Healy ◽  
Edward Dumas ◽  
John Kochendorfer ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Surface Flux ◽  
Methane Emissions ◽  
Surface Fluxes ◽  
The Arctic ◽  
Observation System ◽  
Permafrost Region ◽  
Aircraft Measurements ◽  
The North ◽  
Methane Fluxes

Abstract. The Arctic terrestrial and sub-sea permafrost region contains approximately 30 % of the global carbon stock, and therefore understanding Arctic methane emissions and how they might change with a changing climate is important for quantifying the global methane budget and understanding its growth in the atmosphere. Here we present measurements from a new in situ flux observation system designed for use on a small, low-flying aircraft that was deployed over the North Slope of Alaska during August 2013. The system combines a small methane instrument based on integrated cavity output spectroscopy (ICOS) with an air turbulence probe to calculate methane fluxes based on eddy covariance. We group surface fluxes by land class using a map based on LandSat Thematic Mapper (TM) data with 30 m resolution. We find that wet sedge areas dominate the methane fluxes with a mean flux of 2.1 µg m−2 s−1 during the first part of August. Methane emissions from the Sagavanirktok River have the second highest at almost 1 µg m−2 s−1. During the second half of August, after soil temperatures had cooled by 7 °C, methane emissions fell to between 0 and 0.5 µg m−2 s−1 for all areas measured. We compare the aircraft measurements with an eddy covariance flux tower located in a wet sedge area and show that the two measurements agree quantitatively when the footprints of both overlap. However, fluxes from sedge vary at times by a factor of 2 or more even within a few kilometers of the tower demonstrating the importance of making regional measurements to map out methane emissions spatial heterogeneity. Aircraft measurements of surface flux can play an important role in bridging the gap between ground-based measurements and regional measurements from remote sensing instruments and models.

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