USGS Science⌕ Search
Home/Archive/USGS

USGS · 70047658

Trajectory of the arctic as an integrated system

Larry Hinzman·Clara Deal·Anthony D. McGuire·Sebastian H. Mernild·Igor V. Polyakov·John E. Walsh
View original source ↗Export metadata ↓

Abstract

Although much remains to be learned about the Arctic and its component processes, many of the most urgent scientific, engineering, and social questions can only be approached through a broader system perspective. Here, we address interactions between components of the Arctic System and assess feedbacks and the extent to which feedbacks (1) are now underway in the Arctic; and (2) will shape the future trajectory of the Arctic system. We examine interdependent connections among atmospheric processes, oceanic processes, sea-ice dynamics, marine and terrestrial ecosystems, land surface stocks of carbon and water, glaciers and ice caps, and the Greenland ice sheet. Our emphasis on the interactions between components, both historical and anticipated, is targeted on the feedbacks, pathways, and processes that link these different components of the Arctic system. We present evidence that the physical components of the Arctic climate system are currently in extreme states, and that there is no indication that the system will deviate from this anomalous trajectory in the foreseeable future. The feedback for which the evidence of ongoing changes is most compelling is the surface albedo-temperature feedback, which is amplifying temperature changes over land (primarily in spring) and ocean (primarily in autumn-winter). Other feedbacks likely to emerge are those in which key processes include surface fluxes of trace gases, changes in the distribution of vegetation, changes in surface soil moisture, changes in atmospheric water vapor arising from higher temperatures and greater areas of open ocean, impacts of Arctic freshwater fluxes on the meridional overturning circulation of the ocean, and changes in Arctic clouds resulting from changes in water vapor content.

Explore related subjects

Ecological ApplicationsArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Larry Hinzman, Clara Deal, Anthony D. McGuire, Sebastian H. Mernild, Igor V. Polyakov, John E. Walsh. 2013. Trajectory of the arctic as an integrated system. https://doi.org/10.1890/11-1498.1

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Malady in motion: Chronic wasting disease effects on host movement

Pathogens can have significant impacts on host movement and behavior with consequences for ongoing transmission. For example, chronic wasting disease (CWD) causes severe nutritional deficiencies and neurologic changes, which may alter white-tailed deer ( Odocoileus virginianus ) movement and subsequent transmission risk. Our objectives were to test for changes in movement and habitat selection in deer affected by CWD, and determine the timing of any changes we observed. We leveraged comprehensive movement and mortality data from a large study of free-ranging deer in southwest Wisconsin, a region with high prevalence of CWD. We used necropsy data to identify end stage CWD cases with movement data leading up to death ( n = 44), and sex-, date-, and age-matched test-negative controls. Using GPS collar data, we identified extra-home range excursions and tested for differences in excursion rates, distances, and durations between cases and controls. We evaluated movement characteristics (e.g., movement rates, weekly range sizes) and habitat selection for the two groups, using change point analysis to determine when behavior changes occurred during disease progression. Excursion distances were reduced for CWD cases but were otherwise largely unaffected by infection status. However, CWD cases moved at slower rates and maintained smaller ranges than controls. Habitat selection varied minimally between cases and controls, though CWD cases had an increased preference for proximity to forest edges. While changes in case movement rates and range sizes were detected at or before 6 months prior to death, other movement and habitat selection changes appeared about 2 months prior to death. In addition, CWD cases were frequently in good body condition even within 6 months prior to death, implying that clinically apparent changes occur very late in the disease progression. Our results suggest the occurrence of subclinical and clinical phases of infection, beginning around 6 and 2 months prior to death, respectively. Public communication may therefore benefit from emphasizing that CWD-infected deer are infectious long before they appear sick. Further, because most movement changes occur for very short periods relative to the infectious period of CWD, typical healthy deer movement is likely adequate for representing transmission dynamics for surveillance and management planning.

Wisconsin↗
USGS2026

Improving predictions of insect harassment for barren-ground caribou in the Arctic

Many populations of barren-ground caribou ( Rangifer tarandus ) have declined or are declining, which is concerning given their ecological role in Arctic ecosystems and their societal role in northern communities. Insect harassment is an important driver of the behavior, energetics, and demographic rates of caribou, and yet, due to challenges in predicting harassment, there is limited understanding of how it is responding to changing Arctic conditions. We investigated environmental correlates of mosquito (Culicidae) and oestrid fly (Oestridae) harassment for the Porcupine caribou herd, with the aim of improving our ability to predict harassment. We collected field observations of mosquito activity and used video collars to detect oestrid fly activity across the summer range, which spans the Alaska–Yukon border. Additionally, we documented the composition of harassing insects collected in malaise traps using DNA metabarcoding. We developed predictive mosquito and oestrid fly harassment models using remotely sensed variables relevant to the insects' biology within a nonlinear modeling framework. We then used the top mosquito and oestrid fly models to hindcast predictions of harassment during 1950–2024 and investigate long-term changes in severity and phenology. The top mosquito harassment model included wind speed, temperature, days since snowmelt, precipitation, topographic position, and soil moisture. The top oestrid fly harassment model included temperature, cumulative growing degree days, and time of day. Harassment of both insects was limited at low temperatures (<10°C), with mosquitoes being additionally limited at high temperatures (>22°C) and wind speeds (>7 m/s). The phenology of mosquito and oestrid fly harassment exhibited curvilinear trends across the summer, peaking in midsummer based on the number of days since snowmelt and cumulative growing degree days, respectively. Mosquito harassment also increased with greater soil moisture, precipitation, and at lower relative elevations. Hindcasting indicated that insect harassment notably intensified and advanced over time. Intensifying harassment could decrease caribou foraging opportunities and body condition, and advancing harassment is likely to increasingly overlap with the calving season when calves are most vulnerable. Our results highlight climate-driven changes in insect harassment and provide improved indices for predicting harassment in the Arctic for future applications.

Alaska↗
USGS2026

Application of close-kin mark–recapture to an American black bear population using harvest samples

Close-kin mark–recapture (CKMR) offers a promising alternative to traditional mark–recapture methods for estimating wildlife population parameters. CKMR estimates demographic parameters by identifying genetic relationships between individuals, effectively “recapturing” parental genotypes through their offspring's genetic profiles. One key advantage of CKMR over traditional methods is the ability to estimate abundance without recapture, facilitating the use of lethally collected biological samples. Here, we present an application of CKMR to a terrestrial species using samples collected from harvested individuals. We analyzed genetic data from 1767 American black bears ( Ursus americanus ) harvested over two consecutive years in Michigan's Upper Peninsula. Using Genotyping-in-Thousands by sequencing (GT-seq), we identified parent-offspring pairs and developed sex-specific models tailored to black bear reproductive biology and management strategies. Female population estimates aligned with our expectations, based on prior knowledge of the population. In contrast, male population estimates deviated from expectations, potentially due to an unmodeled combination of factors pertaining to male reproductive biology and sampling bias. Our study not only demonstrates the viability of using harvest-based CKMR for monitoring of terrestrial wildlife populations, but also highlights the need for careful model specification. By providing a novel method to estimate demographic parameters and population size, CKMR using harvest samples can inform management decisions and harvest quotas. This approach leverages existing management practices involving collection of genetic samples, such as mandatory harvest registrations and health monitoring programs. Our findings contribute to the growing body of CKMR applications and expand its use to terrestrial species management.

Michigan↗