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the decline in sea ice is linked to increases in land temperatures and tundra productivity. We use a newly available satellite-derived dataset of Arctic Normalized Difference Vegetation Index (NDVI; J. E. Pinzon et al. 2010, unpublished manuscript) to demonstrate a consistent temporal relationship between sea ice, NDVI, and land temperatures over Arctic tundra. These data permitted the first circumpolar analysis over tundra of NDVI changes in the High Arctic north of 72°N. The spatial patterns
the decline in sea ice is linked to increases in land temperatures and tundra productivity. We use a newly available satellite-derived dataset of Arctic Normalized Difference Vegetation Index (NDVI; J. E. Pinzon et al. 2010, unpublished manuscript) to demonstrate a consistent temporal relationship between sea ice, NDVI, and land temperatures over Arctic tundra. These data permitted the first circumpolar analysis over tundra of NDVI changes in the High Arctic north of 72°N. The spatial patterns
. 2019 ), changing tundra productivity ( Bhatt et al. 2010 ; Bieniek et al. 2015 ), tundra shrub expansion ( Myers-Smith et al. 2011 ), and increased coastal flooding and erosion ( Vermaire et al. 2013 ). These processes have already driven changes to the abundance and management of marine and terrestrial resources [e.g., fisheries and moose ( Alces alces )] ( Mueter and Litzow 2008 ; Perry 2010 ), and even prompted the relocation of villages (e.g., Newtok). Yet, current understanding of Arctic
. 2019 ), changing tundra productivity ( Bhatt et al. 2010 ; Bieniek et al. 2015 ), tundra shrub expansion ( Myers-Smith et al. 2011 ), and increased coastal flooding and erosion ( Vermaire et al. 2013 ). These processes have already driven changes to the abundance and management of marine and terrestrial resources [e.g., fisheries and moose ( Alces alces )] ( Mueter and Litzow 2008 ; Perry 2010 ), and even prompted the relocation of villages (e.g., Newtok). Yet, current understanding of Arctic
1. Introduction Boreal forest and arctic tundra biomes of the northern high latitudes (>40°N) are currently undergoing significant changes coinciding with recent and persistent climatic warming ( Serreze et al. 2000 ; Comiso 2003 ). Terrestrial ecosystem responses to the warming trend include thawing permafrost and deepening soil active layer depths ( Oelke et al. 2004 ), advances in the timing and length of seasonal growing seasons ( Myneni et al. 1997a ; McDonald et al. 2004 ), changes in
1. Introduction Boreal forest and arctic tundra biomes of the northern high latitudes (>40°N) are currently undergoing significant changes coinciding with recent and persistent climatic warming ( Serreze et al. 2000 ; Comiso 2003 ). Terrestrial ecosystem responses to the warming trend include thawing permafrost and deepening soil active layer depths ( Oelke et al. 2004 ), advances in the timing and length of seasonal growing seasons ( Myneni et al. 1997a ; McDonald et al. 2004 ), changes in
1. Introduction A defining feature of Arctic climate change is the striking response of tundra vegetation productivity to increasing summer temperatures, a phenomenon known as the “greening of the Arctic” ( Myneni et al. 1997 ; Jia et al. 2003 ). Remotely sensed trends of vegetation productivity are derived from satellite sensors such as the Advanced Very High Resolution Radiometer (AVHRR); red and near-infrared reflectance are used to calculate the normalized difference vegetation index
1. Introduction A defining feature of Arctic climate change is the striking response of tundra vegetation productivity to increasing summer temperatures, a phenomenon known as the “greening of the Arctic” ( Myneni et al. 1997 ; Jia et al. 2003 ). Remotely sensed trends of vegetation productivity are derived from satellite sensors such as the Advanced Very High Resolution Radiometer (AVHRR); red and near-infrared reflectance are used to calculate the normalized difference vegetation index
far-reaching terrestrial consequences not only for the climate but also for vegetation and other biota in the Arctic ( Bhatt et al. 2010 ; Dutrieux et al. 2012 ; Macias-Fauria et al. 2012 ; Bhatt et al. 2014 ). Tundra vegetation throughout Alaska and the Arctic has largely been greening over the satellite record (1982–2013), and the vegetation productivity rise has been linked to increased summer warmth ( Jia et al. 2003 ; Walker et al. 2003 ) resulting from sea ice retreat ( Bhatt et al. 2010
far-reaching terrestrial consequences not only for the climate but also for vegetation and other biota in the Arctic ( Bhatt et al. 2010 ; Dutrieux et al. 2012 ; Macias-Fauria et al. 2012 ; Bhatt et al. 2014 ). Tundra vegetation throughout Alaska and the Arctic has largely been greening over the satellite record (1982–2013), and the vegetation productivity rise has been linked to increased summer warmth ( Jia et al. 2003 ; Walker et al. 2003 ) resulting from sea ice retreat ( Bhatt et al. 2010
Radiometer (AVHRR) satellite record was not. AVHRR NDVI values showed increases that were in neither the field-measured nor Landsat NDVI records. This result suggested that AVHRR may be demonstrating increasing trends in NDVI that are not occurring on the ground in some Arctic tundra ecosystems. To date, most of the large-scale studies of vegetation greening or browning in Alaska have not included comprehensive structural breaks analysis, designed to simultaneously detect all major disturbances that can
Radiometer (AVHRR) satellite record was not. AVHRR NDVI values showed increases that were in neither the field-measured nor Landsat NDVI records. This result suggested that AVHRR may be demonstrating increasing trends in NDVI that are not occurring on the ground in some Arctic tundra ecosystems. To date, most of the large-scale studies of vegetation greening or browning in Alaska have not included comprehensive structural breaks analysis, designed to simultaneously detect all major disturbances that can
region during the last two decades of the twentieth century. The boundaries of the western Arctic in this study completely encompass the drainage basin of the Yukon River, and the region includes most of Alaska and adjacent areas in northwestern Canada. The region includes two long-term ecological research (LTER) sites: one that is focused on tundra ecosystems (Toolik Lake LTER; Hobbie et al. 1994 ) and another that is focused on boreal forest ecosystems (Bonanza Creek LTER; Chapin et al. 2006
region during the last two decades of the twentieth century. The boundaries of the western Arctic in this study completely encompass the drainage basin of the Yukon River, and the region includes most of Alaska and adjacent areas in northwestern Canada. The region includes two long-term ecological research (LTER) sites: one that is focused on tundra ecosystems (Toolik Lake LTER; Hobbie et al. 1994 ) and another that is focused on boreal forest ecosystems (Bonanza Creek LTER; Chapin et al. 2006
in southern Eurasia in response to enhanced storm activity in northern latitudes ( Serreze et al. 2000 ). Analysis of tree-ring and climate data from the forest–tundra zone of Eurasia indicates that an increasing trend of winter precipitation has led to delayed snowmelt and growing season onset for sub-Arctic Eurasia ( Vaganov et al. 1999 ). Similarly, satellite visible-band observations of regional snow cover from 1976 to 1990 show trends toward earlier spring snow cover disappearance in all
in southern Eurasia in response to enhanced storm activity in northern latitudes ( Serreze et al. 2000 ). Analysis of tree-ring and climate data from the forest–tundra zone of Eurasia indicates that an increasing trend of winter precipitation has led to delayed snowmelt and growing season onset for sub-Arctic Eurasia ( Vaganov et al. 1999 ). Similarly, satellite visible-band observations of regional snow cover from 1976 to 1990 show trends toward earlier spring snow cover disappearance in all
1. Introduction Changes are occurring to high-latitude environments with further alteration likely under several global change scenarios. Responses in the arctic environment may include alterations to the landscape and in water fluxes and stores. While conceptual water balance models have proved useful in assessing contemporary hydrological conditions and in modeling future states, general circulation models have not proved accurate enough to close water budgets in hydrological applications
1. Introduction Changes are occurring to high-latitude environments with further alteration likely under several global change scenarios. Responses in the arctic environment may include alterations to the landscape and in water fluxes and stores. While conceptual water balance models have proved useful in assessing contemporary hydrological conditions and in modeling future states, general circulation models have not proved accurate enough to close water budgets in hydrological applications
production (NPP) is the primary conduit of carbon transfer from the atmosphere to the land surface and is thus a fundamental component of the global carbon cycle. In seasonally frozen environments, vegetation productivity is constrained by low temperatures and plant-available moisture for much of the year, while the active growing season is primarily determined by length of the nonfrozen period ( Jarvis and Linder 2000 ; Kimball et al. 2004 ). Boreal forest and arctic tundra biomes of the northern high
production (NPP) is the primary conduit of carbon transfer from the atmosphere to the land surface and is thus a fundamental component of the global carbon cycle. In seasonally frozen environments, vegetation productivity is constrained by low temperatures and plant-available moisture for much of the year, while the active growing season is primarily determined by length of the nonfrozen period ( Jarvis and Linder 2000 ; Kimball et al. 2004 ). Boreal forest and arctic tundra biomes of the northern high
