the hydrologic cycle and its role in arctic and global...

The Hydrologic Cycle and its Role in Arcticand Global Environmental Change:

A Rationale and Strategy for Synthesis Study

A Report from the Scientific Community to theNational Science Foundation Arctic System Science Program

NSF-ARCSS Hydrology Workshop Steering Committee

Charles Vörösmarty (University of New Hampshire)Larry Hinzman (University of Alaska Fairbanks)Bruce Peterson (Marine Biological Laboratory)David Bromwich (Ohio State University)Lawrence Hamilton (University of New Hampshire)James Morison (University of Washington)Vladimir Romanovsky (University of Alaska Fairbanks)Matthew Sturm (CRREL, Fort Wainwright, Alaska)Robert Webb (NOAA, Boulder, Colorado)

With contributions from scientists at the NSF-ARCSS Hydrology Workshop, Santa Barbara, CA, September 2000

2The Hydrologic Cycle and its Role in Arctic and Global Environmental Change

This report may be cited as:Vörösmarty, C. J., L. D. Hinzman, B. J. Peterson, D. H. Bromwich, L. C. Hamilton, J. Morison, V. E.

Romanovsky, M. Sturm, and R. S. Webb. 2001. The Hydrologic Cycle and its Role in Arctic and Global Envi-ronmental Change: A Rationale and Strategy for Synthesis Study. Fairbanks, Alaska: Arctic Research Consor-tium of the U.S., 84 pp.

Cover photo: Aerial view of Accomplishment Creek and the Sagavanirktok River in the Brooks Range of Alaska. Photo byD. L. Kane.

The workshop and this report were funded by the National Science Foundation under Grant OPP-9910264 andCooperative Agreement #0101279. Any opinions, findings, conclusions, or recommendations expressed in thispublication are those of the authors and do not necessarily reflect the views of the National ScienceFoundation.

3

Acknowledgements ................................................................................. 4

Executive Summary with Key Findings and Recommendations ............ 5Current State of the Art ........................................................................... 5Key Scientific Challenges and Recommendations ................................ 5Major New Synthesis Initiative Required .............................................. 6Implementation of Arctic-CHAMP ........................................................ 6Policy Implications ................................................................................. 7Summary .................................................................................................. 8

1. Introduction ........................................................................................ 9Rationale for Pan-Arctic Hydrologic Synthesis ..................................... 9Report Framework ................................................................................. 13

2. A Strategy for Detecting and Understanding ArcticHydrological Change: Arctic-CHAMP ............................................ 15Arctic-CHAMP Basic Long-Term Monitoring ...................................... 15Arctic-CHAMP Field-Based Process Studies ........................................ 18Arctic-CHAMP Synthesis Modeling ..................................................... 19Execution of Arctic-CHAMP ................................................................. 23

3. Role and Importance of Water in the Arctic System..................... 29The Integrated Water Cycle of the Pan-Arctic ...................................... 29Land ....................................................................................................... 29Atmosphere ............................................................................................ 31Ocean ..................................................................................................... 32Importance of Arctic Hydrology to the Arctic System ........................ 32Importance of the Arctic to the Earth System ..................................... 33

4. Unprecedented Change to Arctic Hydrological Systems ............. 35Changes to the Land-Based Hydrologic Cycle .................................... 35Changes to the Atmosphere ................................................................. 36The Changing Arctic Ocean and its Regional Seas .............................. 40

5. Impacts and Feedbacks Associated with ArcticHydrological Change ...................................................................... 43Direct Impacts on Ecosystems .............................................................. 43Arctic Water Cycle Change and Humans ............................................. 47Land-Atmosphere-Ocean Feedbacks .................................................... 48Land-Atmosphere-Ocean-Human Feedbacks ..................................... 49

6. Implementation of Arctic-CHAMP................................................... 53

References ............................................................................................ 61

Appendix 1. NSF-ARCSS Arctic Hydrology Workshop Participants ..... 71

Appendix 2. Current Gaps in Understanding thePan-Arctic Hydrological Cycle ........................................................ 75

Appendix 3. Integration of Arctic-CHAMP with NSFand Other Federal Agency Initiatives ............................................ 79

Appendix 4. International Collaborations .......................................... 83

Contents


Acknowledgements

The Hydrology Workshop Steering Committee wishes to express itsappreciation to those reviewers from the broader community and to thethirty-three scientists who met in a workshop at the National Center forEcological Analysis and Synthesis (NCEAS) in Santa Barbara, California,to discuss the gaps in our current understanding of arctic hydrology andto formulate a plan for future synthesis studies. Many scientists revieweda draft of this document and provided written comments, which greatlyimproved the final publication.

The Arctic Research Consortium of the United States (ARCUS), throughSue Mitchell, project manager, and Wendy Warnick, executive director,provided publication support, including layout design and development,preparation of graphics, technical editing, and coordination of the publi-cation process. Darlene Dube, administrative assistant at the Universityof New Hampshire (UNH), and Tamara Platt, administrative assistant atthe University of Alaska Fairbanks (UAF), provided much-needed andmuch-appreciated help throughout development of this document. Weare indebted to Jim Reichman and Marilyn Snowball and the staff ofNCEAS for providing a stimulating meeting place and essential work-shop support.

We are also grateful to the National Science Foundation Arctic SystemScience Program for supporting the workshop and the publication of thisdocument.

—Charles Vörösmarty and Larry Hinzman, co-chairsNSF-ARCSS Hydrology Workshop Steering Committee

5

Executive Summarywith Key Findings and Recommendations

T he arctic system con-stitutes a unique and im-portant environmentwith a central role in the

dynamics and evolution of theearth system. The Arctic is inher-ently a highly dynamic system. Yetthere is mounting evidence that itis now experiencing an unprec-edented degree of environmentalchange. Many of these changes arelinked to the arctic hydrologiccycle and are quite possibly theresult of both the direct and indi-rect impacts of human activities.Despite the importance of this is-sue, the current state of the art can-not adequately establish these po-tential linkages to global change.Understanding the full dimensionof arctic change is a fundamentalchallenge to the science commu-nity over the coming decades andwill require a major new effort atinterdisciplinary synthesis. It alsorequires an unprecedented degreeof international cooperation.

Current State of the Art

The water cycle is an inseparableelement of the climate, biology,and biogeochemistry of the arcticregion. The sensitivity of arctic hy-drology to environmental changehas been demonstrated throughdozens of disciplinary studies fo-cused on individual elements ofthe water cycle such as precipita-

tion, evaporation, or runoff. Weknow much less about water-related teleconnections to regionaland global climate. The absence ofcross-disciplinary synthesis studiescontributes to our inability to for-mulate a clear and quantitativepicture of the integrated arctic sys-tem. In the face of global environ-mental change, the arctic sciencecommunity has made predictionsof system-wide impacts, but withlittle confidence.

These key, unresolved issues can becast as a set of scientific questions,fundamentally cross-disciplinaryand synthetic in nature:

• What are the major features (i.e.,stocks and fluxes) of the pan-arctic water balance and how dothey vary over time and space?

• How will the arctic hydrologiccycle respond to natural vari-ability and global change?

• What are the direct impacts ofarctic hydrology changes onnutrient biogeochemistry andecosystem structure and function?

• What are the hydrologic cyclefeedbacks to the oceans andatmosphere in the face of natu-ral variability and globalchange? How will these feed-backs influence human systems?

Key Scientific Challengesand Recommendations

How well are we poised to answersuch questions? A survey of thearctic science community—repre-sented by an interdisciplinaryworkshop convened by ARCSS inSeptember 2000 and summarizedin the remainder of this volume—revealed several notable gaps inour current level of understandingof arctic hydrological systems. Atthe same time, rapidly emergingdata sets, technologies, and model-ing resources provide us with anunprecedented opportunity tomove substantially forward. Threemajor research and synthesis chal-lenges with accompanying recom-mendations for strategic invest-ments in arctic system science aregiven below. Understanding, simu-lating, and predicting contempo-rary and future hydrological dy-namics is greatly limited by:

1.A sparse observational networkfor routine monitoring togetherwith the absence of integrateddata sets of spatial and tempo-rally harmonized biogeophysicalinformation over the pan-arcticdomain. The situation is farfrom optimal and deterioratingrapidly over much of thepan-arctic, especially in Russiaand Canada.

Executive Summary


Recommendations: A substantialcommitment should be made torescue, maintain, and expand cur-rent meteorological and hydrologi-cal data collection efforts. Estab-lishing high-resolution griddedmaps of climatic, hydrologic, topo-graphic, vegetation, and soil prop-erty attributes for the Arctic Oceanwatershed is strongly advised. Ad-ditional resources must be investedin scaling techniques, includingthe expanded use of remote sens-ing. Support for free and open ac-cess to arctic environmental datasets is essential to future progress.Coordination with existing U.S.and international monitoring pro-grams is critical.

2.Numerous gaps in our currentunderstanding of basic scientificprinciples and processes regardingthe water cycle over the entirepan-arctic domain.

Recommendations: Interdisciplinarysynthesis studies linking hydro-logic processes with other depen-dent biogeochemical and biogeo-physical processes should befostered to assemble a more com-plete understanding of the arcticsystem and its role in the broaderearth system. Investments in long-term, process-based hydrologicalfield studies are required.

3.The lack of cross-disciplinary syn-thesis research and modeling todecipher feedbacks arising fromarctic hydrological change on theearth system and on society.

Recommendations: Supportshould be given to integrativeresearch that identifies the uniquerole of arctic hydrosystems in thebroader earth system. An assess-

ment of the feedback mechanismsthrough which progressive hydro-logical change influences bothnatural and human systems isurgently needed. New researchdevoted to establishing quantita-tive linkages between the biogeo-physical and socioeconomicresearch communities is stronglyadvised.

Major New SynthesisInitiative Required

The gaps identified above demon-strate an urgent need to reformu-late the manner in which arctic hy-drological research is funded andexecuted. Implementation of therecommended actions will requirea dedicated research program tosupport arctic hydrological synthe-sis studies. Such a program doesnot now exist, yet has been calledfor as a component of the U.S.Global Change Research Program’sinitiative on the water cycle. Tosupport this new science, thecommittee’s central recommenda-tion is that:

• NSF-ARCSS invest in the devel-opment of a pan-Arctic Commu-nity-wide Hydrological Analysisand Monitoring Program (Arctic-CHAMP) to provide a frame-work for integration studies ofthe pan-arctic water cycle andto articulate the role of fresh-water in terrestrial ecosystem,biogeochemical, biogeophys-ical, ocean, climate, and humandynamics.

The primary aim of Arctic-CHAMPis to catalyze and coordinate inter-disciplinary research with the goalof constructing a holistic under-standing of arctic hydrology

through integration of routineobservations, process-based fieldstudies, and modeling. Four goalsshould guide this effort:

Goal 1: Assess and better under-stand the stocks and fluxeswhich constitute the arctic hy-drologic cycle.

Goal 2: Document changes to thearctic water cycle, contributing ahydrological component to themultiagency SEARCH Program.

Goal 3: Understand the causes ofarctic water cycle change andassess their direct impacts onbiological and biogeochemicalsystems.

Goal 4: Develop predictive simula-tions of the response of the earthsystem and human society tofeedbacks arising from progres-sive changes to arctic hydrologi-cal systems.

Implementation ofArctic-CHAMP

To execute this initiative, the com-mittee strongly recommends:• creating an Arctic-CHAMP Scien-

tific Steering Committee (AC-SSC)to formulate a detailed interdis-ciplinary implementation planand then supervise execution ofthe initiative

• supporting a multidisciplinaryset of process-based catchmentstudies

• initiating a major effort to im-prove our current monitoring ofwater cycle variables, coordinat-ing with U.S. and internationalagency partners as required

• establishing the Arctic-CHAMPSynthesis and Education Center

7

(CSEC) to serve as the physicallocation for several of the scien-tific activities of the program.The center should lead the coor-dination of modeling, field re-search, and monitoring effortswithin CHAMP.

• selecting a core group of Arctic-CHAMP researchers, chosenthrough peer review, to executeprocess studies, monitoring, andmodeling efforts. The researchteam would include principalinvestigators and their post-doc-toral fellows and graduate stu-dents, in residence at CSEC. Theteam would have representativesfrom the biogeophysical and so-cioeconomic realms and includeboth observationalists andmodelers.

• convening an Arctic-CHAMPWorkshop Series and Open Sci-ence Meetings to promote a con-tinuing involvement of the arcticand earth systems science com-munities

• fostering collaboration with themany relevant U.S. arcticresearch initiatives. This willhelp to ensure maximum syn-ergy across programs and avoidduplication of effort. The hydro-logic cycle studies of Arctic-CHAMP could serve as the NSF-ARCSS contribution to themultiagency SEARCH Program.They also will support NSFBiocomplexity and InformationTechnology programs as well aspublic outreach and educationefforts.

• creating and sustaining a vigor-ous set of international scienceand monitoring partnerships.

Most of the pan-arctic land massresides in Russia and Canada.No single National ScienceFoundation program, or even theU.S. arctic research communityas a whole, could achieve thedegree of synthesis required. TheNSF must forge strategic interna-tional partnerships to be success-ful in this endeavor.

Policy Implications

Scientists have yet to observe andunderstand the full dimension ofpan-arctic variability and progres-sive change, but at the same time,they are under increasing pressureto advise the policy-making com-munity as it struggles with howbest to manage the full dimensionof contemporary and future globalchange. The impact of arctic systemchange is likely to extend farbeyond the Arctic per se and thusbecome of critical concern to soci-ety at large. An investment inknowledge is of clear and immedi-ate necessity. The contributions ofan Arctic-CHAMP toward articulat-ing the diverse physical, biological,and human vulnerabilities to thischange provide an important im-petus for international cooperationin wisely managing this criticalpart of the earth system.

Executive Summary


Key Unresolved Scientific Questions

• What are the major features (i.e., stocks and fluxes) of the pan-arctic water balance and how do theyvary over time and space?

• How will the arctic hydrologic cycle respond to natural variability and global change?

• What are the direct impacts of arctic hydrology changes on nutrient biogeochemistry and ecosystemstructure and function?

• What are the hydrologic cycle feedbacks to the oceans and atmosphere in the face of natural variabil-ity and global change? How will these feedbacks influence human systems?

Recommendations• A substantial commitment should be made to rescue, maintain, and expand data collection efforts. Estab-

lishing high-resolution gridded maps of climatic, hydrologic, topographic, vegetation, and soil propertyattributes for the Arctic Ocean watershed is strongly advised. Additional resources must be invested inscaling techniques, including the expanded use of remote sensing.

• Interdisciplinary synthesis studies linking hydrologic processes with other dependent biogeochemical andbiogeophysical processes should be fostered. Investments in long-term, process-based hydrological fieldstudies are required.

• Support integrative research that identifies the unique role of arctic hydrosystems in the broader earthsystem.

• Develop a pan-Arctic Community-wide Hydrological Analysis and Monitoring Program (Arctic-CHAMP).

Arctic-CHAMP Implementation• Create an Arctic-CHAMP Scientific Steering Committee (AC-SSC) to formulate a detailed interdisciplinary

implementation plan and then supervise execution of the initiative.

• Support a multidisciplinary set of process-based catchment studies.

• Initiate a major effort to improve our current monitoring of water cycle variables, coordinating with U.S.and international agency partners as required.

• Establish the Arctic-CHAMP Synthesis and Education Center (CSEC) to serve as the physical location forseveral of the scientific activities of the program. The center should lead the coordination of modeling,field research, and monitoring efforts within CHAMP.

• Convene an Arctic-CHAMP Workshop Series and Open Science Meetings to promote a continuing involve-ment of the arctic and earth systems science communities.

• Foster collaboration with the many relevant U.S. arctic research initiatives. The hydrologic cycle studies ofArctic-CHAMP could serve as the NSF-ARCSS contribution to the multiagency SEARCH Program. Theyalso will support NSF Biocomplexity and Information Technology programs and public outreach andeducation efforts.

• Create and sustain a vigorous set of international science and monitoring partnerships. The NSF mustforge strategic international collaborations to achieve the degree of synthesis required.

9

derstand the rapidly changing stateof the Arctic and predict its futurecondition, we need to synthesizeexisting hydrologic knowledge andto identify gaps in that knowledge.It is critical to organize our currentunderstanding into a frameworkthat captures the essential work-ings and complexities of the arcticwater cycle, taken as a whole. Inthis way we can more effectivelyarticulate the Arctic’s unique placewithin the larger earth system andits role in global change, as calledfor in the recent U.S. GlobalChange Research Program watercycle initiative (USGCRP WaterCycle Study Group 2001).

An understanding of the contem-porary and potential future statesof the arctic hydrological system isa precursor to assessments of theassociated impact on natural eco-systems and human society. Suchassessments must rely on highquality, quantitative informationand are thus critical to sound poli-cies for environmental protection.

The Arctic Water Cycle asan Integrating FrameworkThe hydrologic cycle provides anideal framework for arctic systemsynthesis. First, the arctic hydro-logic system spans three realms:land, ocean, and atmosphere. Sec-ond, the water cycle is more thanjust a set of physical processes: itincludes living things—plant,animal, and human—and they all

Introduction• Assess the state of the art in arctic

systems hydrology and identifyresearch priorities for achievingpredictive understanding of therole of the arctic water cycle inglobal change.

The meeting had broad representa-tion from within the arctic researchcommunity, with more than 30members having expertise in landsurface hydrology, terrestrial andfreshwater ecology, atmosphericdynamics, ocean processes, simula-tion modeling and geo-spatialanalysis (Appendix 1). A steeringcommittee attempted to captureconsensus views articulated duringthe meeting and represented bythis current document. Majorthrusts of the workshop were toarticulate the need for interdiscipli-nary arctic hydrologic studies andto formulate a strategy for newsynthesis research.

Rationale for Pan-ArcticHydrologic Synthesis

The pan-arctic hydrological systemis complex and currently undergo-ing a period of rapid change thatwill influence all aspects of life inthe Arctic. The changes will alsointeract in important ways with theglobal system. In the followingchapters, we document thesechanges and show the complexlinkages within the arctic hydro-logic system and between the arcticand global systems. If we are to un-

T he water cycle of theArctic plays a centralrole in regulating boththe planetary heat bal-

ance and circulation of the globaloceans. Recent and unprecedentedenvironmental changes, such asdeclines in the total area of wintersnow cover on land and decliningsea ice cover throughout the ArcticOcean, are now well documented.Unfortunately, the causes of thesechanges and their impact on theglobal ocean and atmosphere arestill poorly understood. The cycleof freshwater in the arctic land-atmosphere-ocean system is centralto these observed changes (Figure1-1). Yet, knowledge of the hydrol-ogy of the arctic region remainsincomplete due to the complexitiesof permafrost terrain, difficulties inacquiring data in harsh environ-ments, decline in routine monitor-ing, and a lack of interdisciplinaryresearch. Progress in predictingglobal change can only be achievedthrough development of a newmore synthetic and systematic un-derstanding of the water cycle ofthe Arctic.

In September of 2000, a workshopsupported by the National ScienceFoundation Arctic System Science(ARCSS) Program was convened atthe National Center for EcologicalAnalysis and Synthesis in SantaBarbara, California. The work-shop’s central goal was to:

1

1. Introduction


Figure 1-2. Multiscale approach toward achieving synthesis of pan-arctic hydro-logical dynamics and identifying its role in the larger earth system. Informationfrom all scales is necessary to ensure mutual consistency of predictive models.Biophysical, biogeochemical, and human dimension issues should be simulta-neously addressed. (Precipitation over the land area that drains into the ArcticOcean is shown in the lower left panel.)

Local Basin/Region

Figure 1-1. Conceptual diagram of the arctic system, showing linkages amongthe atmosphere, land surface, and ocean systems. Links within the arctic regionas well as the larger earth system must be considered to achieve an integratedview of the hydrological cycle (from Walsh et al. 2001).

Sea Surge,Sea Level

Sea Surge,Sea Level

Freshwaterand

Constituents

Freshwaterand

Constituents

Water,Energy,TraceGases

Wat

er, E

nerg

y,Tr

ace

Gas

es

Wat

er, E

nerg

y

ICE SHEETS(Land Based)

TERRESTRIAL SYSTEMS(Biogeochemistry,

Vegetation Dynamics,Hydrology)

ATMOSPHERE(Climate)

SEA ICEOCEANS

Pan-Arctic Global

interact. Third, the hydrologic cycleis a complex system that cannot beunderstood or predicted fromstudy of its individual parts alone(Woo 1986). This complexity ex-ists over the pan-arctic scale downto the smallest river basin or re-search plot.

The arctic domain may be one ofthe best places to explore the inter-action of land, atmosphere, andoceans through the unique rolethat water plays in linking theserealms (Figures 1-1 and 1-2). It isthe most “closed” and land-domi-nated of all the major ocean basins(Vörösmarty et al. 2000). The Arc-tic Ocean’s connection to globalocean circulation is through tworelatively well-defined exchangesthrough the Bering Strait and Nor-dic Sea. Sea ice generated in theArctic Ocean can be tracked on itsway southward to the Atlantic. At-mospheric exchange is bounded bythe fairly well-identified PolarFront. The domain is relativelypristine, and thus an excellentlaboratory for isolating the effectsof natural variability versus the di-rect impacts of human activity.

Current Arctic WaterCycle ResearchAlthough there is a widespread rec-ognition that arctic hydrology issensitive to global change, anunderstanding of the basic mecha-nisms that control terrestrial watercycling constitutes a major researchneed. Recent ARCSS activities haveclearly identified the importanceof the terrestrial water cycle, re-flected most notably in the LAIIPlan for Action (1997), Modeling theArctic System (1997), Toward anArctic System Synthesis (1998), andToward Prediction of the Arctic Sys-

11

tem (1998) workshop reports andsteering documents. Many of theoverview diagrams in these publi-cations show elements of the ter-restrial water cycle figuring promi-nently in virtually all arctic systemdynamics. Although these reportsrecognize a key role for water inthe arctic system, there remains acompelling need for a coherentframework through which to studyarctic hydrology per se.

A proliferation of traditional disci-plinary research has been success-ful in producing a wealth ofknowledge about individual com-ponents of the hydrologic system(Brown 1968, Dingman 1973,Dingman et al. 1980). However,this body of work does not yet per-mit these pieces to be forged into acomprehensive understanding ofthe whole. Work funded by NSFand other agencies has typicallybeen separated by discipline—hydrology, atmosphere and oceandynamics, biogeochemistry, andecology—and collaborationbetween the disciplines has beenlimited. Essential hydrologic pro-cesses regulating terrestrial ecosys-tem dynamics, for example, haveoften been addressed through in-dependent hydrologic studies andhave not taken advantage of thesynergy possible by the sharing ofresearch sites and experimentaldesign. But the interfaces betweenthese disciplines are likely to bethe very areas where the mostexciting and valuable new researchwill take place. Disciplinary barri-ers need to come down.

The Need for SynthesisIn developing an integrated pictureof arctic hydrology, the scientificcommunity has at its disposal a

broad disciplinary literature thatcan provide a quantitative sum-mary of the pools of water andenergy found in the atmosphere,soil, rivers, lakes, glaciers, sea ice,and ocean waters of the Arctic (Fig-ure 1-3). Estimates of the energyand water transport into and outof the Arctic are also becomingavailable. While providing a usefulbackdrop, collectively these studiesare hardly comprehensive and dif-ficult to interpret from a systemsviewpoint. Because of its integrat-ing role, the arctic water cyclerequires an understanding of theprocesses controlling these poolsand transports. An integrated sci-entific program based on long-term monitoring, field studies, andsimulation could provide animportant path forward. We wouldbe in a much improved position toassess and interpret historic trendsand to make predictions of thefuture.

Development of a synthetic under-standing of the arctic hydrologiccycle will thus require closer col-laboration between modelers andobservationalists. Field measure-ments and process studies providethe data and physical insights forarctic water cycling that underpinmodeling efforts. Models, in turn,provide predictive capability, thecritical ability to extrapolate intime and space needed to addressthe impact of hydrologic change.Models have not yet been ad-equately exploited in designingoptimal arctic monitoring pro-grams, identifying regions wherethe density and distribution ofcritical measurements need to beupgraded, or singling out signifi-cant gaps in our understanding ofthe hydrologic processes. A multi-

disciplinary approach can yieldimportant new insights (Figure1-4). Communication and closecollaboration between these groupsis essential.

NSF-ARCSS Hydrology Workshopparticipants proposed a major sci-entific challenge:• Can we successfully construct a

quantitative and coherent pictureof the arctic water cycle and itslinks to the earth system based onthe current state of knowledge,infrastructure, and institutionalsupport, including all relevantARCSS and non-NSF researchprograms?

A consensus indicated that the an-swer is no. Three major obstacleshave hindered progress:1.A sparse observational network

for routine monitoring togetherwith the absence of integrateddata sets of spatial and tempo-rally harmonized biogeophysicalinformation over the pan-arcticdomain.

2.Numerous gaps in our currentunderstanding of basic scientificprinciples and processes regardingwater cycling in arctic environ-ments.

3.The lack of cross-disciplinary syn-thesis research and modeling todecipher feedbacks on the earthsystem and on society arisingfrom arctic hydrological change.

To address these challenges, theworkshop participants recom-mended development of a pan-Arctic Community-wide Hydro-logical Analysis and MonitoringProgram (Arctic-CHAMP) thatfocuses on arctic water and energycycles. Arctic-CHAMP is planned asa research program with routine

1. Introduction


Figure 1-3. Conceptual model of the arctic hydrological cycle, with key linkages among land, ocean, and atmosphere. Thecoupling of these components within the Arctic and to the larger earth system remains an important yet unresolvedresearch issue. The hydrological cycle is inextricably connected to all biological and chemical processes occurring in thebiosphere, atmosphere, and cryosphere. Hydrologic interactions with terrestrial and aquatic ecosystems and their bio-geochemistry control all life in arctic regions.

J

GG

HHH

I

BBBA

DDDDD

A = atmospheric boundary fluxesB = atmospheric dynamicsC = land-surface atmosphere exchanges (with

vegetation and permafrost dynamics)D = discharge through well-defined flow networks (with

groundwater and river corridor flow)E = runoff from poorly organized lowland flow systems

F = sea ice mass balance and dynamicsG = estuarine controls on terrestrial/shelf interactionsH= changes in glacial mass balance and associated runoffI = direct groundwater discharge to oceanJ = Arctic Ocean dynamics and deep water formationK = biological dynamics and oceanic food chains

13

Figure 1-4. Progressive change in alkalinity of Toolik Lake, Alaska, from long-term, synergistic hydrology and hydrochemical measurements. Chemicalchanges may signal the warming of permafrost in response to global climatechange (Neil Bettez, Arctic LTER database).

0.3

0.4

0.5

0.6

0.7

1975 1979 19851983 1987 1989 1991 1993 1995 1997 1999

Alk

alin

ity

(mill

ieq

uiv

ale

nts

)

1977

observations, focused on process-based field studies, and pan-arcticsynthesis. The workshop partici-pants went on to develop a con-ceptual framework for Arctic-CHAMP and to define its rolewithin NSF-ARCSS.

Report Framework

In the chapters that follow weexplain the scientific reasoning forArctic-CHAMP together with sev-eral practical aspects surroundingits implementation. We begin witha chapter describing the concep-tual design of the Arctic-CHAMP.This chapter is followed by a sum-mary of our current state of knowl-

edge regarding the arctic watercycle and its role in climate, land,and ocean system dynamics. Wethen show evidence for changes tothe arctic water cycle. A chapter isthen presented which is organizedas a brief assessment of our currentunderstanding of the sensitivity ofarctic hydrology to global changeand of the potential feedbacks tothe larger pan-arctic and earth sys-tems. We close with an initial setof recommendations for imple-mentation of Arctic-CHAMP, high-lighting opportunities for collabo-rative work with other U.S. andinternational agency partnersacross the Arctic.

1. Introduction

the hydrologic cycle and its role in arctic and global...

Documents