Biophysical Feedbacks and Transitions in the Arctic Regional System: Life Webs

During the past decade the arctic terrestrial system has been the focus of research under the ARCSS-LAII program, primarily through a series of coordinated field and modeling experiments called ATLAS, FLUX, and ITEX. One key focus of LAII has been to assess arctic terrestrial contributions to the global CO2 budget and surface energy balance. A second focus has been understanding the processes and controls on these mass and energy fluxes. These are, by nature, biophysical processes and feedbacks, so that much of LAII research has gone toward untangling the complex web among vegetation, climate and surface physical processes.

These research efforts have made steady progress over the decade, increasing the scale over which we can extrapolate biophysical processes (working up from plots to sub-regions) and the confidence we have in these extrapolations. The decade also has seen the development of a workable interdisciplinary approach, bringing together physical and biological scientists while developing trust and a common vocabulary and working mode that has allowed these groups to interact successfully.

This progress positions us to begin an exciting new phase of research in which we can address the arctic system as a whole, while we continue to investigate more fully the interaction of the biotic and physical parts of the arctic terrestrial and marine environments. Because of the unique geography and relatively simple biotic systems in the Arctic, this may be the most promising place on Earth to address biocomplexity and biophysical interactions at such a large scale.

The new phase of research also provides an opportunity to tackle areas where we have not done as well during the past decade as we would have likedóspecifically, in the area of assessing and predicting the impacts of changing terrestrial and marine environments, primarily through affected biota, on humans living in the Arctic and elsewhere. Because many arctic residents rely on biotic systems for their livelihood, a sophisticated understanding of arctic biophysical feedbacks and transitions will be an essential underpinning to the Human Dimensions of the Arctic System (HARC) research effort.

Research is needed in three major areas to achieve an understanding of the arctic regional system at a level that will allow prediction of future states, reliable interpretation of paleo-records (PARCS), and the ability to place in context the documented changes in the arctic environment that concern arctic and non-arctic peoples alike (SEARCH) [http://psc.apl.washington.edu/search/]. These areas are:
  1. The biophysical feedbacks and interactions among the components of the arctic system and how they affect its connections to the global system.
  2. The non-linearities, thresholds, and ìsurprisesî in system functioning and state that result from combined complex physical and biological systems.
  3. The vulnerability and resilience of the biotic systems to change, and the relationship of these aspects of the system to human activity and livelihood in the Arctic.
Improving our understanding in these areas is essential if we are to get to the heart of one of the most pressing issues of the dayóare observed changes in the Arctic significant in terms of the impact they will have on people, and are they indicative of future states? Other ARCSS programs (some already in progress, others planned) address these questions, but a program with a specific focus on the biota of the Arctic and their interactions with the physical system, is indispensable if we are to assess the impact of system change on people.
With these ideas as background (draft science plan), we would invite discussion of several critical questions related to life webs: biophysical feedbacks and transitions in the arctic regional system.

Questions
1. Are we in position to delineate the current arctic marine and terrestrial trace gas balance, and can we predict with any certainty how the balance might change under future states and how has it changed in the past?
Are our largest uncertainties in our ability to extrapolate or in understanding and modeling of underlying processes?

2. What are the probable pathways of change and the future states of the arctic land surface? Of the arctic marine environment?
  • Do thresholds exist or will changes be continuous?
  • How will these changes influence the hydrologic cycle, surface energy budget, and trace gas fluxes?
  • Can we constrain our predictions of future states with current knowledge of biophysical processes and paleo-records, or are the two sets of knowledge too disparate?

Arctic residents rely on biotic systems for much of their livelihood.
3. What are the consequences of current and future changes in the biotic systems (terrestrial and marine) on the livelihood of their human residents?
  • Can we predict future states with enough certainty to recognize thresholds, estimate their effects, and mitigate their consequences?
4. How do changes in the arctic region, particularly in its biophysical systems, propagate spatially and temporally?
  • Are we able to recognize, let alone predict, emergent properties as a function of spatial and temporal scale?
  • In what ways must heterogeneity be considered in order to be represented correctly in our system models, and how is the degree of heterogeneity related to system state? How do local rates of biotic change combine at sub-regional and regional levels?
  • Are we able to estimate pan-Arctic response times from our knowledge of local response rates?