scholarly journals How robust is the apparent break‐down of northern high‐latitude temperature control on spring carbon uptake?

2021 ◽  
Author(s):  
Peter Joyce ◽  
Roel Brienen ◽  
Wolfgang Buermann ◽  
Chris Wilson ◽  
Martyn P. Chipperfield ◽  
...  
Keyword(s):  
Temperature Control ◽  
High Latitude ◽  
Carbon Uptake ◽  
Northern High Latitude

Influence of spatial coherence of temperature anomalies on the supposed breakdown of the warmer spring – larger carbon uptake mechanism in northern high latitudes

2020 ◽  
Author(s):  
Peter Joyce ◽  
Manuel Gloor ◽  
Roel Brienen ◽  
Wolfgang Buermann
Keyword(s):  
High Latitude ◽  
Large Scale ◽  
Atmospheric Transport ◽  
Carbon Uptake ◽  
High Latitudes ◽  
Spring Temperature ◽  
Uptake Mechanism ◽  
Temperature Anomalies ◽  
Northern High Latitude ◽  
Significant Change

<p>Land vegetation growth in the northern high latitudes (north of 50˚N) is strongly temperature limited, thus anomalously warm years are expected to result in an increased drawdown of Carbon Dioxide (CO<sub>2</sub>) and vice versa. Piao et al (2017) concluded in an analysis of climate and CO<sub>2</sub> data from Point Barrow, Alaska that there was a weakening response of northern high latitude spring carbon uptake to temperature anomalies over the last 40 years. They proposed that this is due to a weakening control of temperature on productivity. We have analysed northern high latitude climate and remote sensing vegetation indices, as well as atmospheric CO<sub>2</sub> data at Point Barrow, with atmospheric transport analyses of the footprint seen at Barrow. Our results show no large-scale significant change in the spring NDVI-temperature relationship inside the footprint of Barrow, and across the high northern latitudes as a whole. This casts doubt on the assertion that the changing relationship between CO<sub>2</sub> uptake and temperature is driven by a change in vegetation response to temperature. We thus tested several alternative mechanisms that could explain the apparent weakening, including a change in interannual variability of atmospheric transport (i.e. the footprint seen by Barrow) and the spatial agreement of temperature anomalies. We find that the heterogeneity of temperature anomalies increased over time, whereas there is no significant change in interannual variation in the footprint seen by Barrow. These results offer an additional explanation for the apparent decrease in spring temperature sensitivity of northern high latitude CO<sub>2</sub> uptake.</p>

Climatic thresholds shape northern high-latitude fire regimes and imply vulnerability to future climate change

Ecography ◽  
2016 ◽  
Vol 40 (5) ◽  
pp. 606-617 ◽  
Author(s):  
Adam M. Young ◽  
Philip E. Higuera ◽  
Paul A. Duffy ◽  
Feng Sheng Hu
Keyword(s):  
Climate Change ◽  
High Latitude ◽  
Fire Regimes ◽  
Future Climate ◽  
Future Climate Change ◽  
Northern High Latitude

Sub-decadally-resolved Asian monsoon dynamics during Chinese interstadial 21 in response to northern high-latitude climate

2019 ◽  
Vol 172 ◽  
pp. 243-248 ◽  
Author(s):  
Xiuyang Jiang ◽  
Yaoqi He ◽  
Xiaoyan Wang ◽  
Jinguo Dong ◽  
Zhizhong Li ◽  
...  
Keyword(s):  
High Latitude ◽  
Asian Monsoon ◽  
Northern High Latitude ◽  
Monsoon Dynamics

Efficient carbon drawdown allows for a high future carbon uptake in the North Atlantic

2021 ◽  
Author(s):  
Nadine Goris ◽  
Jerry Tjiputra ◽  
Are Ohlsen ◽  
Jörg Schwinger ◽  
Siv Lauvset ◽  
...  
Keyword(s):  
North Atlantic ◽  
High Latitude ◽  
Deep Convection ◽  
Deep Ocean ◽  
Nutrient Supply ◽  
Global Ocean ◽  
Carbon Uptake ◽  
Model Ensemble ◽  
The North ◽  
The North Atlantic

<p>As one of the major carbon sinks in the global ocean, the North Atlantic is a key player in mediating and ameliorating the ongoing global warming. Projections of the North Atlantic carbon sink in a high-CO<sub>2</sub> future vary greatly among models, with some showing that a slowdown in carbon uptake has already begun and others predicting that this slowdown will not occur until nearly 2100.</p><p>Discrepancies among models largely originate because of differences in the efficiency of the high-latitude transport of carbon from the surface to the deep ocean. This transport occurs through biological production, deep convection and subsequent transport via the deep western boundary current. For an ensemble of 11 CMIP5-models, we studied the efficiency of this transport and identified two indicators of contemporary model behavior that are highly correlated with a model´s projected future carbon-uptake. The first indicator is the high latitude summer pCO<sub>2</sub><sup>sea</sup>-anomaly of a model, which is tightly linked to winter mixing and nutrient supply, but also to deep convection. The second indicator is the fraction of the anthropogenic carbon-inventory stored below 1000-m depth, indicating how efficient carbon is transported into the deep ocean. By comparing to the observational database, these indicators allow us to better constrain the model ensemble, and demonstrate that the models with more efficient surface to deep transport are best aligned with current observations. These models also show the largest future North Atlantic carbon uptake, which we then conclude is the more plausible future evolution. We further study if the high correlations between our contemporary indicators and a model´s future North Atlantic carbon uptake is also upheld for the next model generation, CMIP6. We hypothesize that this is the case and that our indicators can not only help us to constrain the CMIP6 model ensemble but also inform us about progress made between CMIP5 and CMIP6 in terms of North Atlantic carbon uptake, winter mixing, nutrient supply, deep convection and transport of carbon into the deep ocean.</p>

scholarly journals Mosaicking Landsat and Sentinel-2 Data to Enhance LandTrendr Time Series Analysis in Northern High Latitude Permafrost Regions

2020 ◽  
Vol 12 (15) ◽  
pp. 2471
Author(s):  
Alexandra Runge ◽  
Guido Grosse
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
High Latitude ◽  
High Latitudes ◽  
Series Analysis ◽  
Data Gaps ◽  
Northern High Latitude ◽  
Study Sites ◽  
Sentinel 2 ◽  
Permafrost Regions

Permafrost is warming in the northern high latitudes, inducing highly dynamic thaw-related permafrost disturbances across the terrestrial Arctic. Monitoring and tracking of permafrost disturbances is important as they impact surrounding landscapes, ecosystems and infrastructure. Remote sensing provides the means to detect, map, and quantify these changes homogeneously across large regions and time scales. Existing Landsat-based algorithms assess different types of disturbances with similar spatiotemporal requirements. However, Landsat-based analyses are restricted in northern high latitudes due to the long repeat interval and frequent clouds, in particular at Arctic coastal sites. We therefore propose to combine Landsat and Sentinel-2 data for enhanced data coverage and present a combined annual mosaic workflow, expanding currently available algorithms, such as LandTrendr, to achieve more reliable time series analysis. We exemplary test the workflow for twelve sites across the northern high latitudes in Siberia. We assessed the number of images and cloud-free pixels, the spatial mosaic coverage and the mosaic quality with spectral comparisons. The number of available images increased steadily from 1999 to 2019 but especially from 2016 onward with the addition of Sentinel-2 images. Consequently, we have an increased number of cloud-free pixels even under challenging environmental conditions, which then serve as the input to the mosaicking process. In a comparison of annual mosaics, the Landsat+Sentinel-2 mosaics always fully covered the study areas (99.9–100 %), while Landsat-only mosaics contained data-gaps in the same years, only reaching coverage percentages of 27.2 %, 58.1 %, and 69.7 % for Sobo Sise, East Taymyr, and Kurungnakh in 2017, respectively. The spectral comparison of Landsat image, Sentinel-2 image, and Landsat+Sentinel-2 mosaic showed high correlation between the input images and mosaic bands (e.g., for Kurungnakh 0.91–0.97 between Landsat and Landsat+Sentinel-2 mosaic and 0.92–0.98 between Sentinel-2 and Landsat+Sentinel-2 mosaic) across all twelve study sites, testifying good quality mosaic results. Our results show that especially the results for northern, coastal areas was substantially improved with the Landsat+Sentinel-2 mosaics. By combining Landsat and Sentinel-2 data we accomplished to create reliably high spatial resolution input mosaics for time series analyses. Our approach allows to apply a high temporal continuous time series analysis to northern high latitude permafrost regions for the first time, overcoming substantial data gaps, and assess permafrost disturbance dynamics on an annual scale across large regions with algorithms such as LandTrendr by deriving the location, timing and progression of permafrost thaw disturbances.

scholarly journals Reviews and syntheses: Changing ecosystem influences on soil thermal regimes in northern high-latitude permafrost regions

2018 ◽  
Vol 15 (17) ◽  
pp. 5287-5313 ◽  
Author(s):  
Michael M. Loranty ◽  
Benjamin W. Abbott ◽  
Daan Blok ◽  
Thomas A. Douglas ◽  
Howard E. Epstein ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Energy ◽  
High Latitude ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Energy Partitioning ◽  
Climate Feedback ◽  
Permafrost Soil ◽  
Thermal Dynamics ◽  
Northern High Latitude

Abstract. Soils in Arctic and boreal ecosystems store twice as much carbon as the atmosphere, a portion of which may be released as high-latitude soils warm. Some of the uncertainty in the timing and magnitude of the permafrost–climate feedback stems from complex interactions between ecosystem properties and soil thermal dynamics. Terrestrial ecosystems fundamentally regulate the response of permafrost to climate change by influencing surface energy partitioning and the thermal properties of soil itself. Here we review how Arctic and boreal ecosystem processes influence thermal dynamics in permafrost soil and how these linkages may evolve in response to climate change. While many of the ecosystem characteristics and processes affecting soil thermal dynamics have been examined individually (e.g., vegetation, soil moisture, and soil structure), interactions among these processes are less understood. Changes in ecosystem type and vegetation characteristics will alter spatial patterns of interactions between climate and permafrost. In addition to shrub expansion, other vegetation responses to changes in climate and rapidly changing disturbance regimes will affect ecosystem surface energy partitioning in ways that are important for permafrost. Lastly, changes in vegetation and ecosystem distribution will lead to regional and global biophysical and biogeochemical climate feedbacks that may compound or offset local impacts on permafrost soils. Consequently, accurate prediction of the permafrost carbon climate feedback will require detailed understanding of changes in terrestrial ecosystem distribution and function, which depend on the net effects of multiple feedback processes operating across scales in space and time.

scholarly journals Assessment of the theoretical limit in instrumental detectability of northern high-latitude methane sources using <i>δ</i><sup>13</sup>C<sub>CH4</sub> atmospheric signals

2019 ◽  
Vol 19 (19) ◽  
pp. 12141-12161 ◽  
Author(s):  
Thibaud Thonat ◽  
Marielle Saunois ◽  
Isabelle Pison ◽  
Antoine Berchet ◽  
Thomas Hocking ◽  
...  
Keyword(s):  
High Latitude ◽  
Oil And Gas ◽  
Transport Model ◽  
Isotopic Signatures ◽  
Sources And Sinks ◽  
Regional Sources ◽  
Northern High Latitude ◽  
Source Signal ◽  
Methane Source ◽  
Remote Sites

Abstract. Recent efforts have brought together bottom-up quantification approaches (inventories and process-based models) and top-down approaches using regional observations of methane atmospheric concentrations through inverse modelling to better estimate the northern high-latitude methane sources. Nevertheless, for both approaches, the relatively small number of available observations in northern high-latitude regions leaves gaps in our understanding of the drivers and distributions of the different types of regional methane sources. Observations of methane isotope ratios, performed with instruments that are becoming increasingly affordable and accurate, could bring new insights on the contributions of methane sources and sinks. Here, we present the source signal that could be observed from methane isotopic 13CH4 measurements if high-resolution observations were available and thus what requirements should be fulfilled in future instrument deployments in terms of accuracy in order to constrain different emission categories. This theoretical study uses the regional chemistry-transport model CHIMERE driven by different scenarios of isotopic signatures for each regional methane source mix. It is found that if the current network of methane monitoring sites were equipped with instruments measuring the isotopic signal continuously, only sites that are significantly influenced by emission sources could differentiate regional emissions with a reasonable level of confidence. For example, wetland emissions require daily accuracies lower than 0.2 ‰ for most of the sites. Detecting East Siberian Arctic Shelf (ESAS) emissions requires accuracies lower than 0.05 ‰ at coastal Russian sites (even lower for other sites). Freshwater emissions would be detectable with an uncertainty lower than 0.1 ‰ for most continental sites. Except Yakutsk, Siberian sites require stringent uncertainty (lower than 0.05 ‰) to detect anthropogenic emissions from oil and gas or coal production. Remote sites such as Zeppelin, Summit, or Alert require a daily uncertainty below 0.05 ‰ to detect any regional sources. These limits vary with the hypothesis on isotopic signatures assigned to the different sources.

scholarly journals Pronounced and unavoidable impacts of low-end global warming on northern high-latitude land ecosystems

2020 ◽  
Vol 15 (4) ◽  
pp. 044006 ◽  
Author(s):  
Akihiko Ito ◽  
Christopher P O Reyer ◽  
Anne Gädeke ◽  
Philippe Ciais ◽  
Jinfeng Chang ◽  
...  
Keyword(s):  
Global Warming ◽  
High Latitude ◽  
Northern High Latitude
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