Changing Seasonality in the Arctic System (CSAS)

There now exists abundant evidence that pervasive changes are underway in the patterns of seasonality in the Arctic. Shifts in the timing, length, and pattern of individual seasonal events are occurring throughout the arctic system, including physical events (e.g., ocean and atmospheric circulation and fluxes, precipitation, sudden thaws, presence of ice and snow), biological events (e.g., plant phenology, animal life history events) and human activities (e.g., resource use, industrial activities).

The National Science Foundation's (NSF) Arctic System Science Program (ARCSS) released an announcement of opportunity for Changing Seasonality in the Arctic System (CSAS; See Witness the Arctic, Volume 13, Number 3) in June 2008. The solicitation for research focused on interdisciplinary work, including field studies, retrospective investigation, modeling, or synthesis to explore the changing arctic system.

NSF ARCSS received 71 individual proposals in response to the solicitation, representing approximately $30 million in requested funding—40 awards totaling $14.3 million were made. More than 85% of the funding was provided through funds from the American Recovery and Reinvestment Act.

The ARCSS Program funded 17 projects; two additional relevant projects were funded through other programs in the NSF Arctic Sciences Division OPP-ARC and so are included on this website.

CSAS Projects

How the Timing of Summer Precipitation Affects the Responses of Boreal Forest to Climate Change

Dates:

1 July 2009 to 30 June 2013

There is increasing evidence that ecological processes at high latitude are just as sensitive to the timing of events as to their magnitudes. In the boreal forest, moisture availability in summer affects both tree growth and the fire regime. Summers are brief and seasonal transitions rapid, so even slight shifts in the timing of precipitation patterns can have large impacts. One of the most striking seasonal phenomena in the Alaskan boreal forest is the onset of frequent frontal storms in late summer. This event usually comes in mid-July but is delayed into August or even September in some years. Summers...

How Does Changing Seasonality Affect the Capacity of Arctic Stream Networks to Influence Nutrient Fluxes from the Landscape to the Ocean?

Dates:

1 September 2009 to 31 August 2013

Stream networks are intimately connected to the landscapes through which they flow and significantly transform nutrients and organic matter that are in transport from landscapes to oceans. In previous research we studied several arctic headwater streams to determine how the seasonal development of the thaw basin (thawed sediments under streams) interacts with the hyporheic zone (a layer of surface sediments that contains water which exchanges continuously with water in the open channel). During this study we measured significant rates of net N and P regeneration from (or uptake by) the hyporheic zone during the mid-summer. In many cases this regeneration...

Effects of Lengthening Growing Season and Increasing Temperature on Soil Carbon Fluxes and Stocks in Arctic Tundra

Dates:

1 September 2009 to 31 August 2010

This one-year pilot project supports PI to test a new soil respiration measurement method and the possibility to manipulate temperature in the Arctic tundra. We warmed the tundra ecosystems with open-top chambers, conducted trenching experiment, and measured soil respiration with the continuous CO2 profile system. Our preliminary data show that the tundra can be effectively warmed by our designed open-top chambers to an average of 0.3-3.1°C above the control plots. The CO2 sensors buried in soils can be effectively used to measure CO2 concentration and CO2 fluxes in the tundra. Our preliminary results indicated that soil respiration varied between 1.0...

Effects of Warming-Induced Increases in Shrub Abundance and Changing Seasonality on Migratory Songbirds in Alaskan Arctic Tundra

Dates:

1 September 2009 to 31 August 2015

Our project extends beyond changes in vegetation, and considers the cascade of changes that is triggered when Arctic vegetation and seasonality are altered. As highlighted by the Arctic Climate Impact Assessment (ACIA), in contrast to plants, the response of animal populations to simulated or current climate changes has been drastically understudied in the Alaskan interior and much of the Arctic. We were funded by the US National Science Foundation’s Office of Polar Programs (NSF-OPP) for five years (2010-2014), to study the effects that warming-induced increases in shrub abundance and changing seasonality have on migratory songbirds in Alaskan Arctic tundra. We...

A Change of Seasonality of the Upper Arctic Ocean in Response to Atmospheric and Sea Ice Forcing

Dates:

1 July 2009 to 30 June 2013

The PI proposes to investigate the change of seasonality of the Arctic Ocean Ekman transport and upwelling/downwelling, and their relationships to key components of the arctic system. A systematic investigation of the Arctic Ocean upwelling and its change of seasonality is needed in order to understand complex interactions among components of a rapidly changing arctic system. Upwelling is arguably the single most important dynamical variable in oceanography. It forces oceanic gyres through the Sverdrup balance. Upwelling replenishes nutrients in the surface layer and helps to sustain phytoplankton production. It is a conduit for heat flux from the warm Atlantic Water...

Impacts of the Changing Seasonality of Wind-Driven Mixing on the Arctic System

Dates:

1 August 2009 to 30 September 2013

The Arctic is generally considered a very quiet ocean. The sea ice impedes the generation and damps both surface and internal waves - and mixing rates in the water column are consequently generally very small. When we start looking at specific events in more detail, however, we found that when there is no ice the Arctic Ocean is actually a pretty active ocean. Storms generate intense of inertial motions throughout the water column. These motions affect the stratification and the vertical distribution of properties in the water column. We believe that this is a key factor in understanding the present...

Pan-Arctic Climate and Ecosystem Response to Historical and Projected Changes in the Seasonality of Sea Ice Melt and Growth

Dates:

1 August 2009 to 31 July 2013

The primary goal of this work is to explore the causes and effects of ongoing seasonal changes in the annual cycle of sea ice. This includes a quantitative assessment of the drivers and effects of the seasonal timing of sea ice melt onset, freezing initiation, and snowfall within the observational record and coupled climate model simulations of historical and future climate. We are examining this from both energy budget and ecosystem perspectives and are explicitly considering feedbacks to the Arctic and global systems. In particular, we are investigating the interactions between seasonal changes in the surface marine state and shortwave...

Seasonality of Circumpolar Tundra: Ocean and Atmosphere Controls and Effects on Energy and Carbon Budgets

Dates:

1 September 2009 to 31 August 2013

The goals of this project are: to characterize the spatial and temporal seasonality of tundra vegetation of the circumpolar Arctic in relation to ice-ocean, atmospheric, and land characteristics to understand the seasonal linkages between the marine environment, the atmosphere, and the terrestrial ecosystems of the Arctic, and to examine the effects of seasonality changes in terrestrial vegetation on Arctic carbon dynamics. The project is divided into the three broad components: Component 1: Circumpolar seasonality characterization. Our earlier work examined interannual trends of vegetation greenness, land-surface temperatures, and sea-ice concentrations. In the proposed work, we will focus on the seasonal variability...

The Changing Seasonality of Tundra Nutrient Cycling: Implications for Ecosystem and Arctic System Functioning

Dates:

1 September 2009 to 31 August 2012

Arctic soils have large stores of carbon (C) and may act as a significant CO2 source with warming. However, the key to understanding tundra soil processes is nitrogen (N), as both plant growth and decomposition are severely N limited. However, current models of tundra ecosystems and their responses to climate change assume that while N limits plant growth, C limits decomposition. In addition, N availability is strongly seasonal with relatively high availability early in the growing season followed by a pronounced crash. There is a need to understand the controls on this seasonality to predict arctic system responses to climate...

The Seasonal Response of the Arctic and Global Climate System to Projected Sea Ice Loss within the Context of GHG-Induced Climate Change

Dates:

1 September 2009 to 31 August 2013

The objective of the project is to identify robust seasonal changes in the Arctic climate system to projected Arctic sea ice loss, and to place these into the context of global-scale changes due to increasing greenhouse gas concentrations (GHGs). We examine physical and biological changes in the atmosphere, ocean, and land using the newest versions of the NCAR Community Climate System Model (CCSM) and Community Earth System Model (CESM) as our primary tool. To date, our project has investigated the following issues: Climatological characteristics of the planetary boundary layer over the Arctic Ocean and adjacent continents in models and various...

Timing is Everything: Seasonality and Phenological Dynamics Linking Species, Communities and Trophic Feedbacks in the Low vs. High Arctic

Dates:

1 July 2009 to 30 June 2013

We are collecting data on phenological dynamics of plants in response to observed and experimental warming, at the species- and community scales, at study sites in Kangerlussuaq and Zackenberg, Greenland. The focus of the data collection is at Kangerlussuaq, where we have expanded our long-term monitoring plots and added some experimental warming plots using open-topped chambers to compare the spatial dynamics of species-specific responses to warming at small and larger spatial scales. Simultaneously, we are continuing our observations on the timing of onset and progression of the season of parturition by caribou and muskoxen at Kangerlussuaq and by muskoxen at...

Tracking the Seasonal Contribution of Algal Fatty Acids to the Arctic Marine System

Dates:

15 September 2009 to 31 August 2013

The overall goal of this project relates to providing an exceptional level of ecological detail by: 1) tracing the seasonal inputs of specific fatty acid biomarkers deriving from sea ice alga and open ocean phytoplankton through the marine food web using sophisticated fatty acid profiling and novel compound-specific stable isotope analyses (CSIA); 2) tracing the seasonal (spring and summer) changes in the proportions of these biomarkers in sympagic, pelagic and benthic arctic marine invertebrates; 3) investigating the presence of these seasonally derived biomarkers in ice seals, which are an important subsistence resource to Alaskan Native communities in the region. Our...

Changing Seasonality of the Arctic: Alteration of Production Cycles and Trophic Linkages in Response to Changes in Sea Ice and Upper Ocean Physics

Dates:

15 August 2009 to 31 July 2013

Significant changes in the arctic environment have been detected in recent years. One of the most striking changes is the decline of arctic sea ice. A diminished arctic ice cover may have a profound effect on all components of the marine ecosystem. Despite the extreme polar conditions, the Arctic Ocean supports a complex pelagic food web that includes zooplankton, fish, birds, seals, walruses, whales and the top predator, the polar bear. At the base of the food chain, supporting all the marine life, are the phytoplankton and algae that produce organic carbon. The central hypothesis of this collaborative research is...

Seasons of Change in the Arctic Environment

Dates:

1 July 2009 to 30 June 2013

The arctic system is strongly defined by its seasonality. The extreme annual cycle of solar radiation, interactions between the Arctic and lower latitudes, within-arctic interactions between the land, ocean, and atmosphere, and the energetics of freeze and thaw, combine to lend a complexity and richness to arctic seasonality not seen elsewhere on the planet. This seasonality is changing. Summer sea ice extent is declining, attended by strong autumn rises in air temperature over the Arctic Ocean. Active layer freeze-up in Siberia is occurring later in the winter. These and other emerging changes will become more prominent in coming decades, with...

Analysis and Attribution of Changes in Siberian Hydroclimate and Implications for the Future

Dates:

1 September 2009 to 31 August 2013

This work will document observed changes in the hydroclimatology of the Siberian region, attribute these changes to specific physical mechanisms in the context of climate change, and study the impact of those changes from the regional to the hemispheric weather and climate. The project will use observational analysis and modeling experiments to investigate the links between arctic sea ice trends and changes to seasonal snow cover. The autumn snow cover is of particular interest due to its persistent increases over the last two decades despite the robust warming trend and its connection to stratosphere- troposphere coupling and hemispheric variability in...

Shifting Seasonality of Arctic River Hydrology Alters Key Biotic Linkages Among Aquatic Systems

Dates:

1 July 2009 to 30 June 2013

Our goal is to determine how the shifting seasonality of Arctic river hydrology alters key biotic linkages within and between lake and stream components of watersheds and may alter the function of the Arctic system. Arctic grayling (Thymallus arcticus) is a quintessential, circumpolar Arctic species that provides a model system for understanding the impacts of changing seasonality on arctic ecosystem function because an interconnected and varied landscape (large tundra rivers, small streams and lakes) is required to maintain their population viability. Changes to environmental conditions that disrupt their migration will affect the system-level function of aquatic ecosystems. Grayling serve as...

Shifting Seasonality of Northern Forest Response to Arctic Environmental Change

Dates:

15 June 2009 to 31 May 2013

This is an investigation of the response of northern boreal forests to changes in arctic seasonality using an existing circumpolar network of centennial to millennial-length tree-ring width and density records that will be integrated with targeted field observations, satellite data and modeling efforts. The sensitivity of northern forests to arctic warming and related seasonality effects is likely to be highly complex, involving shifts in the timing and dynamics of multiple factors that can significantly impact tree growth. Researchers will assess network-based as well as limited new tree-ring data from sites along a latitudinal gradient in northeastern Alaska, one of the...

Understanding Climate-Driven Phenological Change: Observations, Adaptations, and Cultural Implications in Northeastern Siberia and Labrador/Nunatsiavut

Dates:

1 September 2009 to 31 August 2013

This project is an interdisciplinary effort to systematically document, model, and interpret key linkages between physical, biological and human systems in the context of changing seasonality (phenology) due to global and local climate change. In line with the CSAS solicitation, the primary research objective of PHENARC is to understand the linkages between Arctic system climate change, altered phenological processes, and adaptations and responses of human societies to these changes to decipher implications for the future. The project’s overarching research questions are: i) What are the key seasonal events that form an integral part of the ecosystems in PHENARC’s two main...

Diamonds and Oil from the Tundra: A System Study on the Impact of Changing Seasons on Mining and Oil Exploration

Dates:

1 July 2009 to 30 June 2013

Natural resource extraction is the backbone of the arctic economy. Oil and gas exploration and production taxes account for 88% of the State of Alaska’s revenue, providing $10.2 billion in fiscal year 2008. In addition, 4,400 direct and 37,344 indirect Alaskan jobs are due to this industry. In Canada, oil and gas are also crucial to the economy, but so too is diamond mining, with a total value of diamond extraction in the Northwest Territories of $2 billion in 2007. As a result, Canada is the 3rd largest diamond producer in the world. The mines employ about 4,000 people, roughly...