Kyle Arndt

Woodwell Climate Research Center | WHRC

Our understanding of how rapid Arctic warming and permafrost thaw affect global climate dynamics is restricted by limited spatio-temporal data coverage due to logistical challenges and the complex landscape of Arctic regions. It is therefore crucial to make best use of the available observations, including the integrated data analysis across discip...

Increasing wildfire occurrence and intensity have immediate effects on northern ecosystems due to combustion of aboveground vegetation and belowground soil organic matter. These immediate impacts have indirect and longer term effects, including deepening of the active layer, changes in soil decomposition rates, and shifts in plant community composi...

Ecosystems at high latitudes are changing rapidly in response to climate change. To understand changes in carbon fluxes across seasonal to multi‐decadal timescales, long‐term in situ measurements from eddy covariance networks are needed. However, there are large spatiotemporal gaps in the high‐latitude eddy covariance network. Here we used the rela...

Global atmospheric concentrations of nitrous oxide have been increasing over previous decades with emerging research suggesting the Arctic as a notable contributor. Thermokarst processes, increasing temperature, and changes in drainage can cause degradation of polygonal tundra landscape features resulting in elevated, well-drained, unvegetated soil...

Globally, winter temperatures are rising, and snowpack is shrinking or disappearing entirely. Despite previous research and published literature reviews, it remains unknown whether biomes across the globe will cross important thresholds in winter temperature and precipitation that will lead to significant ecological changes. Here, we combine the wi...

The positive Arctic–methane (CH4) feedback forms when more CH4 is released from the Arctic tundra to warm the climate, further stimulating the Arctic to emit CH4. This study utilized the CLM-Microbe model to project CH4 emissions across five distinct Arctic tundra ecosystems on the Alaska North Slope, considering three Shared Socioeconomic Pathway...

Wetlands are the largest natural source of methane (CH4) emissions globally. Northern wetlands (>45° N), accounting for 42 % of global wetland area, are increasingly vulnerable to carbon loss, especially as CH4 emissions may accelerate under intensified high-latitude warming. However, the magnitude and spatial patterns of high-latitude CH4 emission...

Introduction Enteric methane (CH 4 ) emissions are one of the largest components of the anthropogenic CH 4 budget, and with accelerating climatic changes, there are calls to reduce anthropogenic greenhouse gas emissions. Certain seaweeds fed as supplements can reduce enteric CH 4 emissions from ruminant animals by as much as 80%; however, these stu...

While previously thought to be negligible, carbon emissions during the non-growing season (NGS) can be a substantial part of the annual carbon budget in the Arctic boreal zone (ABZ), which can shift the carbon balance of these ecosystems from a long-held annual carbon sink towards a net annual carbon source. The purpose of this review is to summari...

Ecosystems at high latitudes are under increasing stress from climate change. To understand changes in carbon fluxes, in situ measurements from eddy covariance networks are needed. However, there are large spatiotemporal gaps in the high-latitude eddy covariance network. Here we used the relative extrapolation error index in machine learning-based...

Ecosystems at high latitudes are under increasing stress from climate change. To understand changes in carbon fluxes, in situ measurements from eddy covariance networks are needed. However, there are large spatiotemporal gaps in the high-latitude eddy covariance network. Here we used the relative extrapolation error index in machine learning-based...

Arctic-boreal landscapes are experiencing profound warming, along with changes in ecosystem moisture status and disturbance from fire. This region is of global importance in terms of carbon feedbacks to climate, yet the sign (sink or source) and magnitude of the Arctic-boreal carbon budget within recent years remains highly uncertain. Here, we prov...

The continued warming of the Arctic could release vast stores of carbon into the atmosphere from high-latitude ecosystems, especially from thawing permafrost. Increasing uptake of carbon dioxide (CO2) by vegetation during longer growing seasons may partially offset such release of carbon. However, evidence of significant net annual release of carbo...

Long-term atmospheric CO2 records suggest a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent de...

The continued warming of the Arctic could release vast stores of carbon into the atmosphere from high-latitude ecosystems, especially from thawing permafrost. Increasing uptake of carbon dioxide (CO2) by vegetation during longer growing seasons may partially offset such release of carbon. However, evidence of significant net annual release of carbo...

Spatial heterogeneity in methane (CH4) flux requires a reliable upscaling approach to reach accurate regional CH4 budgets in the Arctic tundra. In this study, we combined the CLM-Microbe model with three footprint algorithms to scale up CH4 flux from a plot level to eddy covariance (EC) tower domains (200 m × 200 m) in the Alaska North Slope, for t...

The warming of the Arctic is 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 b...

Understanding the sources and sinks of methane (CH4) is critical to both predicting and mitigating future climate change. There are large uncertainties in the global budget of atmospheric CH4, but natural emissions are estimated to be of a similar magnitude to anthropogenic emissions. To understand CH4 flux from biogenic sources in the United State...

Arctic warming is affecting snow cover and soil hydrology, with consequences for carbon sequestration in tundra ecosystems. The scarcity of observations in the Arctic has limited our understanding of the impact of covarying environmental drivers on the carbon balance of tundra ecosystems. In this study, we address some of these uncertainties throug...

Pastures and rangelands are a dominant portion of global agricultural land and have the potential to sequester carbon (C), mitigating climate change. Management intensive grazing (MIG), or high-density rotational grazing through paddocks with long rest periods, has been highlighted as a method of enhancing soil C in pastures by increasing forage pr...

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...

Arctic warming is affecting snow cover and soil hydrology, with consequences for carbon sequestration in tundra ecosystems. The scarcity of observations in the Arctic has limited our understanding of the impact of covarying environmental drivers on the carbon balance of tundra ecosystems. In this study, we address some of these uncertainties throug...

Understanding the sources and sinks of CH4 is critical to both predicting and mitigating future climate change. There are large uncertainties in the global budget of atmospheric CH4, but natural emissions are estimated to be of a similar magnitude to total anthropogenic emissions. The largest sources of uncertainty in scaling bottom-up CH4 estimate...

Soil respiration (i.e. from soils and roots) provides one of the largest global fluxes of carbon dioxide (CO2) to the atmosphere and is likely to increase with warming, yet the magnitude of soil respiration from rapidly thawing Arctic-boreal regions is not well understood. To address this knowledge gap, we first compiled a new CO2 flux database for...

Management intensive grazing (MIG), also known as rotational grazing or multi-paddock grazing, is purported to sequester carbon (C) in soils compared to other agricultural management systems. Prior research examining the potential for MIG to enhance soil C has been inconclusive, and past investigations have not addressed whether higher nitrous oxid...

The rates, processes, and controls on Arctic cold period soil carbon loss are still poorly understood. To understand one component of winter CO2 loss in the atmosphere, continuous measurements of soil (CO2) were made and compared to ecosystem scale CO2 fluxes. Measurements of soil (CO2) were made near Utqiaġvik, Alaska from the beginning of soil th...

Arctic tundra exhibits large landscape heterogeneity in microtopography, hydrology, and active layer depth. While many carbon flux measurements and experiments are done at or below the mesoscale (≤ 1km), modern ecosystem carbon modeling is often done at scales of 0.25° to 1.0° latitude, creating a mismatch between processes, process input data, and...

Cold seasons in Arctic ecosystems are increasingly important to the annual carbon balance of these vulnerable ecosystems. Arctic winters are largely harsh and inaccessible leading historic data gaps during that time. Until recently, cold seasons have been assumed to have negligible impacts on the annual carbon balance but as data coverage increases...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Many studies have reported that the Arctic is greening; however, we lack an understanding of the detailed patterns and processes that are leading to this observed greening. The normalized difference vegetation index (NDVI) is used to quantify greening, which has had largely positive trends over the last few decades using low spatial resolution sate...

Recent warming in the Arctic, which has been amplified during the winter1,2,3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO2)⁴. However, the amount of CO2 released in winter is not known and has not been well represented by ecosystem models or empirically based estimates5,6. Here we sy...

The atmospheric methane (CH4) concentration, a potent greenhouse gas, is on the rise once again, making it critical to understand the controls on CH4 emissions. In Arctic tundra ecosystems, a substantial part of the CH4 budget originates from the cold season, particularly during the “zero curtain” (ZC), when soil remains unfrozen around 0 °C. Due t...

The Pan-Arctic has been observed to be "greening" or "browning" measured by increased or decreases respectfully in the normalized difference vegetation index (NDVI). These trends are observed on a large scale using coarse satellite imagery which is necessary to cover the large region and reduced data size. However, this comes with the caveat that t...

The concentration of atmospheric methane (CH 4), a 28-times more powerful greenhouse gas than carbon dioxide (CO 2), is increasing at the fastest rate in the last twenty years, making it critical to understand the controls on CH 4 emissions from terrestrial ecosystems. We show that autumn terrestrial CH 4 enhancements (atmospheric concentrations ov...

Arctic warming continues to occur at an unprecedented rate, causing increased methane (CH4) and carbon dioxide (CO 2) emissions in an environment that has been a long-term carbon sink. Warming in these regions destabilizes large soil carbon deposits, making the Arctic particularly vulnerable to positive feedback amplification. Sub-surface CO 2 and...

The springtime transition to regional‐scale onset of photosynthesis and net ecosystem carbon uptake in boreal and tundra ecosystems is linked to the soil freeze‐thaw state. We present evidence from diagnostic and inversion models constrained by satellite fluorescence and airborne CO2 from 2012‐2014 indicating the timing and magnitude of spring carb...

Numerous studies have examined the effect of sediment particle size and distribution on community structure, but few have focused explicitly on how physical habitat characteristics influence biogeochemical functions of freshwater biofilms. In this study, we evaluated the effect of particle size and heterogeneity on rates of biofilm metabolism and n...

Over the last decade, the methane (CH4) atmospheric concentration is increasing at the fastest rate since the last twenty years, and isotopic analyses show that this increase is due to increased emissions from ecosystems (Nisbet et al., 2016; Kirschke et al., 2013). Northern high latitudes wetlands have substantial potential in affecting atmospheri...

The Arctic is warming at twice the global rate. Arctic soils contain twice as much carbon as the global atmosphere giving the Arctic potential for positive feedbacks impacting global change. Fall emissions of carbon dioxide (CO2) and methane (CH4) are increasingly contributing to the yearly carbon budget especially during a the zero curtain, where...

Arctic permafrost is a large contributor of methane (CH4) and an increasing source of carbon dioxide (CO2) to the atmosphere. This makes the tundra a very large carbon store that is at risk of being lost to the atmosphere. Winter emissions have recently been found to be a significant contributor to the net yearly flux of carbon (CO2 and CH4). CH4 i...