title: Synthesis of effects in four Arctic subregions.
abstract: An assessment of impacts on Arctic terrestrial ecosystems has emphasized geographical variability in responses of species and ecosystems to environmental change. This variability is usually associated with north-south gradients in climate, biodiversity, vegetation zones, and ecosystem structure and function. It is clear, however, that significant east-west variability in environment, ecosystem structure and function, environmental history, and recent climate variability is also important. Some areas have cooled while others have become warmer. Also, east-west differences between geographical barriers of oceans, archipelagos and mountains have contributed significantly in the past to the ability of species and vegetation zones to relocate in response to climate changes, and they have created the isolation necessary for genetic differentiation of populations and biodiversity hot-spots to occur. These barriers will also affect the ability of species to relocate during projected future warming. To include this east-west variability and also to strike a balance between overgeneralization and overspecialization, the ACIA identified four major sub regions based on large-scale differences in weather and climate-shaping factors. Drawing on information, mostly model output that can be related to the four ACIA subregions, it is evident that geographical barriers to species re-location, particularly the distribution of landmasses and separation by seas, will affect the northwards shift in vegetation zones. The geographical constraints--or facilitation--of northward movement of vegetation zones will affect the future storage and release of carbon, and the exchange of energy and water between biosphere and atmosphere. In addition, differences in the ability of vegetation zones to re-locate will affect the biodiversity associated with each zone while the number of species threatened by climate change varies greatly between subregions with a significant hot-spot in Beringia. Overall, the subregional synthesis demonstrates the difficulty of generalizing projections of responses of ecosystem structure and function, species loss, and biospheric feedbacks to the climate system for the whole Arctic region and implies a need for a far greater understanding of the spatial variability in the responses of terrestrial arctic ecosystems to climate change.
authors.affiliation: Abisko Scientific Research Station, Sweden. terry.callaghan@ans.kiruna.se
authors.forename: Terry V
authors.initials: TV
authors.lastname: Callaghan
authors.forename: Lars Olof
authors.initials: LO
authors.lastname: Björn
authors.forename: Yuri
authors.initials: Y
authors.lastname: Chernov
authors.forename: Terry
authors.initials: T
authors.lastname: Chapin
authors.forename: Torben R
authors.initials: TR
authors.lastname: Christensen
authors.forename: Brian
authors.initials: B
authors.lastname: Huntley
authors.forename: Rolf A
authors.initials: RA
authors.lastname: Ims
authors.forename: Margareta
authors.initials: M
authors.lastname: Johansson
authors.forename: Dyanna
authors.initials: D
authors.lastname: Jolly
authors.forename: Sven
authors.initials: S
authors.lastname: Jonasson
authors.forename: Nadya
authors.initials: N
authors.lastname: Matveyeva
authors.forename: Nicolai
authors.initials: N
authors.lastname: Panikov
authors.forename: Walter
authors.initials: W
authors.lastname: Oechel
authors.forename: Gus
authors.initials: G
authors.lastname: Shaver
authors.forename: Sibyll
authors.initials: S
authors.lastname: Schaphoff
authors.forename: Stephen
authors.initials: S
authors.lastname: Sitch
authors.forename: Christoph
authors.initials: C
authors.lastname: Zöckler
mesh_terms: D000818:Animals; D001110:Arctic Regions; D044822:Biodiversity; D002244:Carbon / Q000378:metabolism; D003081:Cold Climate; D003247:Conservation of Natural Resources; D017753:Ecosystem; D004784:Environmental Monitoring; D010944:Plants; D014466:Ultraviolet Rays
chemical_list: D002244:Carbon