The morphology of experimentally produced charcoal distinguishes fuel types in the Arctic tundra

The Holocene ◽  
2020 ◽  
Vol 30 (7) ◽  
pp. 1091-1096 ◽  
Author(s):  
Eleanor MB Pereboom ◽  
Richard S Vachula ◽  
Yongsong Huang ◽  
James Russell
Keyword(s):  
Arctic Tundra ◽  
Global Carbon Cycle ◽  
Fire Frequency ◽  
The Arctic ◽  
Fuel Type ◽  
The Past ◽  
Primary Means ◽  
Forested Ecosystems ◽  
Global Carbon ◽  
Tundra Ecosystems

Wildfires in the Arctic tundra have become increasingly frequent in recent years and have important implications for tundra ecosystems and for the global carbon cycle. Lake sediment–based records are the primary means of understanding the climatic influences on tundra fires. Sedimentary charcoal has been used to infer climate-driven changes in tundra fire frequency but thus far cannot differentiate characteristics of the vegetation burnt during fire events. In forested ecosystems, charcoal morphologies have been used to distinguish changes in fuel type consumed by wildfires of the past; however, no such approach has been developed for tundra ecosystems. We show experimentally that charcoal morphologies can be used to differentiate graminoid (mean = 6.77; standard deviation (SD) = 0.23) and shrub (mean = 2.42; SD = 1.86) biomass burnt in tundra fire records. This study is a first step needed to construct more nuanced tundra wildfire histories and to understand how wildfire will impact the region as vegetation and fire change in the future.

Mineral dust coupled with climate-carbon cycle on orbital timescales over the past 4 Ma

2021 ◽  
Author(s):  
Mengmeng Cao ◽  
Zhixiang Wang ◽  
Ze Zhang ◽  
Anguo Xiao
Keyword(s):  
Carbon Cycle ◽  
Deep Sea ◽  
Mineral Dust ◽  
Ice Sheet ◽  
Global Carbon Cycle ◽  
The Arctic ◽  
The Past ◽  
Dust Flux ◽  
Arctic Ice ◽  
Global Carbon

<p>Mineral dust is one of the environmental component for forcing the global climatic change, and not only influences the amount of solar radiation incoming the earth surface, but affects atmospheric CO<sub>2</sub> concentrations in the past through wind transport to ocean and subsequent biological pumping. Mineral dust is one of the important driving factors for variations of atmospheric CO<sub>2 </sub>content in Quaternary glacial-interglacial cycles. Here, we reconstruct the interaction between the Asian dust flux (as a representative of the global dust flux), the cryosphere system (δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub>), and the global carbon cycle since 4 Ma using phase analysis, power decomposition analysis, obliquity sensitivity calculation and evolutionary spectral analysis. The evolutionary spectra show that orbital-scale variability of mineral dust, δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub> and δ<sup>13</sup>C<sub>benthic</sub> are very similar over the past 4 Ma, except the interval time of 3-2 Ma that shows higher obliquity energy (higher O/T values) of the δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub> and δ<sup>13</sup>C<sub>benthic</sub> data. Therefore, we suggest that the Asian and/or global dust is acted as a transmitter transporting the periodic signals stored in the Arctic ice sheet to deep-sea δ<sup>13</sup>C<sub>benthic</sub>. This is why δ<sup>13</sup>C<sub>benthic</sub> data have very similar changes with the Arctic ice sheets on the orbital scale. Sharp increase of global dust flux after 1.6 Ma resulted in a significant weakening of the 405 kyr long eccentricity power of δ<sup>13</sup>C<sub>benthic</sub> series because Arctic ice sheet signals strongly inhibit the influences of low-latitude solar insolation variations on deep-sea δ<sup>13</sup>C<sub>benthic</sub> system. In addition, we suggest that strengthened global drought and increases of dust fluxes since late Miocene probably forced the anti-phase relationship between δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub> and δ<sup>13</sup>C<sub>benthic</sub> around 6 Ma, rather than the expansion of Arctic ice sheet. Our results highlight the close coupling between dust fluxes and the global carbon cycle, with deeply influencing marine productivity and land surface processes.</p><p><strong>Keywords: </strong>mineral dust; deep sea oxygen isotope (δ<sup>18</sup>O<sub>benthic</sub> ); deep sea carbon isotope(δ<sup>13</sup>C<sub>benthic</sub>); orbital  periods ; inland Asia</p>

scholarly journals Fire and Carbon Cycling in the Subalpine Forests of Yellowstone National Park

2006 ◽  
Vol 30 ◽  
pp. 65-67
Author(s):  
Daniel Kashian ◽  
Daniel Tinker ◽  
Monica Turner ◽  
William Romme ◽  
Michael Ryan
Keyword(s):  
Field Study ◽  
Yellowstone National Park ◽  
National Park ◽  
Carbon Sink ◽  
Global Carbon Cycle ◽  
Fire Frequency ◽  
Carbon Stocks ◽  
Ecosystem Production ◽  
Changes Over Time ◽  
Global Carbon

Our research group carried out two projects through UW-NPS and the AMK Ranch in 2007, a field study (project #1) and a workshop for managers (project #2). In 2004 we had initiated a field study of carbon stocks along a replicated chronosequence of stands in Yellowstone National Park that had burned at varying times from ca. 1700 AD through 1988. In each stand we measured all of the major carbon pools (including live biomass, dead biomass, and soil carbon) to characterize changes over time in net ecosystem production (the net balance between carbon uptake and loss from an ecosystem). These empirical data were then used to evaluate the potential effects of changing climate and changing fire frequency on how the Yellowstone landscape as a whole functions as either a carbon sink or a carbon source in the global carbon cycle.

scholarly journals Spatiotemporal patterns of tundra fires: late-Quaternary charcoal records from Alaska

2015 ◽  
Vol 12 (3) ◽  
pp. 3177-3209 ◽  
Author(s):  
M. L. Chipman ◽  
V. Hudspith ◽  
P. E. Higuera ◽  
P. A. Duffy ◽  
R. Kelly ◽  
...  
Keyword(s):  
Climate Change ◽  
Late Quaternary ◽  
Rotation Period ◽  
Arctic Tundra ◽  
Ecosystem Processes ◽  
Anthropogenic Climate Change ◽  
The Arctic ◽  
Spatial And Temporal Patterns ◽  
The Past ◽  
Tundra Ecosystem

Abstract. Anthropogenic climate change has altered many ecosystem processes in the Arctic tundra and may have resulted in unprecedented fire activity. Evaluating the significance of recent fires requires knowledge from the paleo-fire record because observational data in the Arctic span only several decades, much shorter than the natural fire rotation in Arctic tundra regions. Here we report results of charcoal analysis on lake sediments from four Alaskan lakes to infer the broad spatial and temporal patterns of tundra fire occurrence over the past 35 000 years. Background charcoal accumulation rates are low in all records (range = 0–0.05 pieces cm-2 year-1), suggesting minimal biomass burning across our study areas. Charcoal peak analysis reveals that the mean fire return interval (FRI; years between consecutive fire events) ranged from 1648 to 6045 years at our sites, and that the most recent fire events occurred from 882 to 7031 years ago, except for the CE 2007 Anaktuvuk River Fire. These mean FRI estimates are longer than the fire rotation periods estimated for the past 63 years in the areas surrounding three of the four study lakes. This result suggests that the frequency of tundra burning was higher over the recent past compared to the late Quaternary in some tundra regions. However, the ranges of FRI estimates from our paleo-fire records overlap with the expected values based on fire-rotation-period estimates from the observational fire data, and thus quantitative differences are not significant. Together with previous tundra-fire reconstructions, these data suggest that the rate of tundra burning was spatially variable and that fires were extremely rare in our study areas throughout the late Quaternary. Given the rarity of tundra burning over multiple millennia in our study areas and the pronounced effects of fire on tundra ecosystem processes such as carbon cycling, dramatic tundra ecosystem changes are expected if anthropogenic climate change leads to more frequent tundra fires.

Representing Arctic coastal erosion in the Max Planck Institute Earth System Model (MPI-ESM)

2020 ◽  
Author(s):  
David Marcolino Nielsen ◽  
Johanna Baehr ◽  
Victor Brovkin ◽  
Mikhail Dobrynin
Keyword(s):  
Carbon Cycle ◽  
Sea Ice ◽  
Coastal Erosion ◽  
Global Carbon Cycle ◽  
System Model ◽  
The Arctic ◽  
Earth System ◽  
Max Planck ◽  
Erosion Rates ◽  
Global Carbon

<p>The Arctic has warmed twice as fast as the globe and sea-ice extent has decreased, causing permafrost to thaw and the duration of the open-water period to extend. This combined effect increases the vulnerability of the Arctic coast to erosion, which in turn releases substantial amounts of carbon to both the ocean and the atmosphere, potentially contributing to further warming due to a positive climate-carbon cycle feedback. Therefore, Arctic coastal erosion is an important process of the global carbon cycle.</p><p>Comprehensive modelling studies exploring Arctic coastal erosion within the Earth system are still in their infancy. Here, we describe the development of a semi-empirical Arctic coastal erosion model and its coupling with the Max Planck Institute Earth System Model (MPI-ESM). We also present preliminary results for historical and future climate projections of coastal erosion rates in the Arctic. The coupling consists on the exchange of a combination of driving forcings from the atmosphere and the ocean, such as surface air temperature, winds and sea-ice concentration, which result in annual coastal erosion rates. In a further setp, organic matter from the eroded permafrost is provided to the ocean biogeochemistry model and, consequently, to the global carbon cycle including atmospheric CO<sub>2</sub>.</p>

Modelling the global carbon cycle for the past and future evolution of the earth system

1999 ◽  
Vol 159 (1-4) ◽  
pp. 305-317 ◽  
Author(s):  
Siegfried Franck ◽  
Konrad Kossacki ◽  
Christine Bounama
Keyword(s):  
Carbon Cycle ◽  
Global Carbon Cycle ◽  
Earth System ◽  
Future Evolution ◽  
The Past ◽  
The Earth ◽  
Global Carbon

Influence of Southern Ocean dynamics on Antarctic temperatures and on the global carbon cycle over the past two millennia.

2021 ◽  
Author(s):  
Hugues Goosse ◽  
Zhiqiang Lyu ◽  
Laurie Menviel ◽  
Katrin Meissner ◽  
Anne Mouchet
Keyword(s):  
Carbon Cycle ◽  
Southern Ocean ◽  
Ocean Circulation ◽  
Global Carbon Cycle ◽  
Ocean Dynamics ◽  
Temperature History ◽  
Joint Analysis ◽  
The Past ◽  
Reconstructed Temperature ◽  
Global Carbon

<p>Reconstructions of Antarctic surface temperature covering the past millennia display a large centennial variability that is not synchronous with fluctuations recorded on other continents and which is generally not well simulated by models. Many processes can be at the origin of these temperature variations such as teleconnections with tropical oceans and changes in the Southern Ocean. The focus here will be on the latter, in particular on the influence of westerly winds that have a large impact on the exchange of heat and carbon between the ocean and atmosphere. Changes in the Southern Ocean circulation and stratification also influence the carbon cycle at global scale. It is generally suggested that atmospheric CO<sub>2</sub> variations over the past two millennia were mainly controlled by land processes but the Southern Ocean might have also played a role. We will thus test whether the joint analysis of Antarctic temperature and atmospheric CO<sub>2</sub> concentration fluctuations can inform us on the origin of the observed changes over this period. In this purpose, we use the climate model LOVECLIM which includes a representation of the global carbon cycle. Experiments over the last two millennia will address the sensitivity to realistic perturbations of the wind stress. Finally, experiments with data assimilation will allow assessing what constraints are needed for model results to better reproduce the atmospheric CO<sub>2</sub> concentration and reconstructed temperature history.</p>

Facies control on carbonate δ13C on the Great Bahama Bank

Geology ◽  
2021 ◽  
Author(s):  
Emily C. Geyman ◽  
Adam C. Maloof
Keyword(s):  
Global Carbon Cycle ◽  
Global Ocean ◽  
Seawater Chemistry ◽  
Great Bahama Bank ◽  
The Past ◽  
Carbon Isotopic ◽  
Lime Mud ◽  
Stratigraphic Record ◽  
Vital Effects ◽  
Global Carbon

The carbon isotopic (δ13C) composition of shallow-water carbonates often is interpreted to reflect the δ13C of the global ocean and is used as a proxy for changes in the global carbon cycle. However, local platform processes, in addition to meteoric and marine diagenesis, may decouple carbonate δ13C from that of the global ocean. We present new δ13C measurements of benthic foraminifera, solitary corals, calcifying green algae, ooids, coated grains, and lime mud from the modern Great Bahama Bank. We find that vital effects, cross-shelf seawater chemistry gradients, and meteoric diagenesis produce carbonate with δ13C variability rivaling that of the past two billion years of Earth history. Leveraging Walther’s Law, we illustrate how these local δ13C signals can find their way into the stratigraphic record of bulk carbonate.

scholarly journals Response of vegetation and carbon fluxes to brown lemming herbivory in Northern Alaska

2021 ◽  
Author(s):  
Jessica Plein ◽  
Rulon W. Clark ◽  
Kyle A. Arndt ◽  
Walter C. Oechel ◽  
Douglas Stow ◽  
...  
Keyword(s):  
Carbon Fluxes ◽  
Arctic Tundra ◽  
The Arctic ◽  
Co2 Uptake ◽  
Co2 Fluxes ◽  
Environmental Controls ◽  
Global Rate ◽  
Tundra Ecosystem ◽  
The Impact ◽  
Tundra Ecosystems

Abstract. The Arctic is warming at double the average global rate, affecting the carbon cycle of tundra ecosystems. Most research on carbon fluxes from Arctic tundra ecosystems has focused on abiotic environmental controls (e.g. temperature, rainfall, or radiation). However, Arctic tundra vegetation, and therefore the carbon balance of these ecosystems, can be substantially impacted by herbivory. In this study we tested how vegetation consumption by brown lemmings (Lemmus trimucronatus) can impact carbon exchange of a wet-sedge tundra ecosystem near Utqiaġvik, Alaska during the summer, and the recovery of vegetation during a following summer. We placed brown lemmings in individual enclosure plots and tested the impact of lemmings’ herbivory on carbon dioxide (CO2) and methane (CH4) fluxes and the normalized difference vegetation index (NDVI) immediately after lemming removal and during the following growing season. During the first summer of the experiment, lemmings’ herbivory reduced plant biomass (as shown by the decrease in the NDVI) and decreased CO2 uptake, while not significantly impacting CH4 emissions. Methane emissions were likely not significantly affected due to CH4 being produced deeper in the soil and escaping from the stem bases of the vascular plants. The summer following the lemming treatments, NDVI and CO2 fluxes returned to magnitudes similar to those observed before the start of the experiment, suggesting recovery of the vegetation, and a transitory nature of the impact of lemming herbivory. Overall, lemming herbivory has short-term but substantial effects on carbon sequestration by vegetation and might contribute to the considerable interannual variability in CO2 fluxes from tundra ecosystems.

scholarly journals Spatiotemporal patterns of tundra fires: late-Quaternary charcoal records from Alaska

2015 ◽  
Vol 12 (13) ◽  
pp. 4017-4027 ◽  
Author(s):  
M. L. Chipman ◽  
V. Hudspith ◽  
P. E. Higuera ◽  
P. A. Duffy ◽  
R. Kelly ◽  
...  
Keyword(s):  
Climate Change ◽  
Late Quaternary ◽  
Rotation Period ◽  
Arctic Tundra ◽  
Ecosystem Processes ◽  
Anthropogenic Climate Change ◽  
The Arctic ◽  
Spatial And Temporal Patterns ◽  
The Past ◽  
Tundra Ecosystem

Abstract. Anthropogenic climate change has altered many ecosystem processes in the Arctic tundra and may have resulted in unprecedented fire activity. Evaluating the significance of recent fires requires knowledge from the paleofire record because observational data in the Arctic span only several decades, much shorter than the natural fire rotation in Arctic tundra regions. Here we report results of charcoal analysis on lake sediments from four Alaskan lakes to infer the broad spatial and temporal patterns of tundra-fire occurrence over the past 35 000 years. Background charcoal accumulation rates are low in all records (range is 0–0.05 pieces cm−2 yr−1), suggesting minimal biomass burning across our study areas. Charcoal peak analysis reveals that the mean fire-return interval (FRI; years between consecutive fire events) ranged from ca. 1650 to 6050 years at our sites, and that the most recent fire events occurred from ca. 880 to 7030 years ago, except for the CE 2007 Anaktuvuk River Fire. These mean FRI estimates are longer than the fire rotation periods estimated for the past 63 years in the areas surrounding three of the four study lakes. This result suggests that the frequency of tundra burning was higher over the recent past compared to the late Quaternary in some tundra regions. However, the ranges of FRI estimates from our paleofire records overlap with the expected values based on fire-rotation-period estimates from the observational fire data, and the differences are statistically insignificant. Together with previous tundra-fire reconstructions, these data suggest that the rate of tundra burning was spatially variable and that fires were extremely rare in our study areas throughout the late Quaternary. Given the rarity of tundra burning over multiple millennia in our study areas and the pronounced effects of fire on tundra ecosystem processes such as carbon cycling, dramatic tundra ecosystem changes are expected if anthropogenic climate change leads to more frequent tundra fires.

Sign in / Sign up

Export Citation Format

Share Document