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Blubber samples from Alaska ringed seal (Phoca hispida) were collected for inclusion in the US National Biomonitoring Specimen Bank, as well as for immediate analysis as part of the contaminant monitoring component of the US National Marine Fisheries Service's Marine Mammal Health and Stranding Response Program. The blubber samples were analyzed for organochlorine (OC) contaminants (e.g., PCB congeners, pesticides, DDTs). Results for ringed seals from the Alaska Arctic revealed low blubber concentrations of OC contaminants. Differences in contaminant concentrations among the Alaska seals may be explained by differences in feeding habits and migratory patterns; age or gender did not appear to account for the differences observed. The integration of real-time contaminant monitoring with specimen banking provides important baseline data that can be used to plan and manage banking activities. This includes identifying appropriate specimens that are useful in assessing temporal trends and increasing the utility of the banked samples in assessing chemical contaminant accumulation and relationships to biological effects.
Objectives were to measure a suite of organochlorine contaminants in tissues of Arctic fox collected on the Pribilof Islands for comparison to similar measurements in Arctic fox from other locations for the AMAP assessment.
1. Sediment study for heavy metals and selected organic contaminants. 2. Analysis of benthic organisms for heavy metals and selected organic contaminants. 3. Study of suspended sediment distribution, composition and sources. 4. Determination of partitioning of heavy metals between dissolved and particulate phases.
I. Objectives: I.1. To determine the normal range of values (natural variability due to time of year, age, gender) for basic nutritional and health parameters (blubber characteristics, essential and non-essential elements, structure of basic tissues) in the bowhead whale. a. Blubber thickness (depth and girth), chemical composition (lipids, water, calories), and tissue structure (light microscopy and special stains) will be assessed. b. Essential and non-essential elements (heavy metals) will be measured in liver and kidney. c. Tissue structure (light microscopy) characteristics obviously related to nutritional status in liver (glycogen, lipid and lipofuscin stores), pancreas (zymogen granules), and intestine (mucosal microvilli) and any evidence of inactivity/atrophy will be examined. d. Documentation of "normal" structure of basic tissues and evaluation for evidence of disease will also be conducted. I.2. Using data from Objective 1 to identify the parameters most important in assaying the health status of other mysticetes residing in the Bering Sea or Western Arctic that are harvested or stranded. I.3. Using data from Objective 1 to help determine the role of the bowhead whale as an indicator of ecosystem health and development of an optimized protocol for assessing mysticete health for the Bering Sea and Western Arctic, and other regions.
1. Research area # 2 in the 1998/99 Announcement of Opportunity by CIFAR, "Study of anthropogenic influences on the Western Arctic/Bering Sea Ecosystem", and 2. Research area #4 in the 1998/99 Announcement of Opportunity by CIFAR, "Contaminant inputs, fate and effects on the ecosystem" specifically addressing objectives a-c, except "effects." a. "Determine pathways/linkages of contaminant accumulation in species that are consumed by top predators, including humans, and determine sub-regional differences in contaminant levels..." b. "Use an ecosystems approach to determine the effects of contaminants on food web and biomagnification." c. "Encourage local community participation in planning and implementing research strategies." The objectives of Phase I, Human Ecology Research are to: 1. Document reliance by indigenous arctic marine communities in Canada, Alaska and Russia on arctic resources at risk from chemical pollutants; and, 2. Incorporate traditional knowledge systems of subsistence harvesting. The human ecology components of the project were conducted within the frameworks of indigenous environmental knowledge and community participation. Using participatory mapping techniques, semi-structured interviews and the direct participation of community members in research design, data collection and implementation, research and data collection on the human ecology of indigenous arctic marine communities was undertaken in the communities of Holman, NWT (1998), Wainwright, Alaska (1999), and is underway in Novoe Chaplino, Russia. (2000).
The first part of the present study evaluated tissue concentrations of twelve essential and non-essential elements in four arctic marine mammal species important as subsistence resources to indigenous Alaskans. Species sampled included: bowhead whales, beluga whales, ringed seals, and polar bears. Concentrations of As, Cd, Co, Cu, Pb, Mg, Mn, Hg, Mo, Se, Ag, and Zn, were analyzed in liver, kidney, muscle, blubber, and epidermis (the latter in cetaceans only). Elements that were identified as having tissue concentrations, which in domesticated species would have been considered higher than normal and/or even toxic, were Cd, Hg, Ag, and Se. However, the concentrations of these elements were consistent with previous reports for arctic marine mammals. Remaining elements were at concentrations within normal ranges for domesticated species, although Cu was found frequently at concentrations that would be considered marginal or deficient in terrestrial domesticated animals. Across-species comparisons revealed that Cd was highest in kidney, followed by liver in all four species. Its concentrations were frequently correlated with Cu, Zn, Hg, and Se. Cadmium accumulated with age in bowhead and beluga whales, especially in liver and kidney. The relationships between Cd and Hg, and between Cd and Se were believed to be due to mutual accretion with age, although direct interactions could not be ruled out, especially with respect to Cd and Se. Associations between Cd and Cu, and Cd and Zn were potentially attributable to mutual binding with the inducible protein, metallothionein. This assumption was supported by the observation that Cd:Zn ratios in liver and kidney displayed a significant linear relationship to age and that this ratio either increased slightly (in kidney and liver of bowheads) or remained constant (in kidney and liver of belugas) with age. In general, Se was highest in liver and kidney of all four species, where it was frequently at concentrations that would have been deemed elevated or toxic for domesticated species, although within ranges previously reported for arctic marine mammals. Selenium increased with age indices, and was highly correlated with Hg, and often with Cd as well. Mercury also increased with age, and liver contained the highest tissue concentration in the cetacean and pinniped species. The pattern of Se accumulation in polar bears differed, with highest concentrations found in kidney, which suggested that this tissue may be the primary site for Hg detoxification in this species, as is the case for terrestrial mammals. Compared to the other three species, bowhead whales had very low Hg concentrations in all tissues. The highly significant linear relationship between Hg and Se noted in various tissues (particularly liver) of all four species was presumed due to binding of these two elements to each other following demethylation of MHg. This assumption was supported by the observations that while Se and Hg both accumulated with age, the fraction of total Hg that was composed of MHg decreased with age. The quantity that represented the difference between total Hg measured directly and calculated total Hg [i.e., SHg = Hg(II) + MHg], also increased with age in beluga liver. This connoted that a portion of the total Hg present was in an organic form other than MHg, and that this form accumulated with age. Alternatively, this portion, which was apparently not measured by either the Hg(II) or MHg procedures, may have been lost during extraction. Species in this study had mean hepatic Hg:Se molar ratios that were below unity. This implies that Hg concentrations may have been below some threshold level, after which subsequent accumulation proceeds in a 1:1 molar ratio fashion with Se. Alternatively, it might suggest that a 1:1 Hg:Se molar ratio is not a prerequisite for protection from Hg toxcosis among marine mammals, because none of the animals in the present study exhibited lesions typically associated with Hg toxicosis. In beluga liver, concentrations of Ag were elevated when compared to domesticated species. The only element that showed a significant linear association to Ag was Cu—a relationship that was observed in all four species. This suggested that Ag and Cu may be associated through a common ligand, possibly metallothionein. The association between Ag and Se in beluga liver was less strong than that between Hg and Se; moreover, Ag did not increase with age. These findings indicate that Ag probably does not compete with Hg for Se binding, and therefore is unlikely to substantially inhibit detoxification of Hg in beluga whales. In the second portion of this research, tissues from bowhead whales, beluga whales and ringed seals were examined at both the gross and light microscopic level. The purpose of this evaluation was three-fold: to describe the normal histologic appearance of tissues; to perform a routine histologic survey of tissues that would contribute to a general health assessment, and; to scrutinize tissues for lesions that might support a diagnosis of toxicosis caused by Cd, Hg, Ag, or Se. Tissues examined were chosen on the basis of their propensity to be targets for toxicologic injury from the specified elements (with the exception of brain) and included, but were not limited to, the tissues analyzed chemically. Special stains were used to identify particular pigments or tissue components. Overall, the bowhead whales evaluated appeared healthy and had low parasite burdens. The most common lesion, which was observed in all bowheads, was a non-inflammatory chronic renal periglomerular and interstitial fibrosis. This lesion was not typical of Cd-induced nephropathy, and it did not appear to be associated with renal Cd burdens. Nevertheless, thresholds of Cd-induced renal injury are not known for cetacean species, and more whales need to be examined histologically in conjunction with analysis of tissue Cd residues. Acute myodegeneration was observed in cardiac and/or skeletal muscle of a few bowheads, and was presumed to reflect a hunting-induced exertional myopathy. The beluga whales examined were generally in good body condition and appeared healthy grossly, but they had much higher parasite burdens than bowhead whales. In particular, prevalence in belugas of pulmonary nematodiasis was high, being especially common among whales obtained from Pt. Hope compared to those from Pt. Lay. Grossly, firm, caseous nodules were associated with lungworms, while histologically, the associated pulmonary changes ranged from mild chronic inflammation and focal granuloma formation to catarrhal granulomatous and eosinophilic verminous bronchopneumonia. Another change observed in some belugas and believed to be associated with lungworm infection, was multifocal pulmonary arterial medial hypertrophy and degeneration. Beluga whales harvested at Pt. Lay (summer) frequently showed evidence of hepatic and pancreatic atrophy, while whales taken at Pt. Hope (spring) did not. This was believed to result from anorexia during migration—a supposition corroborated by the lack of stomach contents among Pt. Lay whales. Another prominent histologic finding among belugas was hepatic telangectasia, which occurred with significantly greater frequency and severity in Pt. Hope belugas than in those from Pt. Lay. The etiology and significance of this lesion could be not be ascertained, although it was not believed to be associated with any of the elements analyzed in this study. Mild thickening of Bowman’s capsule was seen frequently in belugas. However, this lesion was not typical of Hg or Cd-induced nephropathies, and did not appear correlated with kidney concentrations of these metals. This lesion was believed to be a normal consequence of aging in belugas, although a metal etiology for it could not be excluded irrefutably. In general, ringed seals were in good body condition and appeared healthy on gross examination. Among seals evaluated histologically, the most common finding was a mild, chronic, focal or periportal hepatitis, with focal hepatocellular necrosis sometimes apparent. Although a metal etiology for this lesion could not be definitively ruled out, in the absence of other lesions that would support a diagnosis of metal toxicosis, an infectious etiology was considered more credible. Two out of sixteen seals had embryologic remnants (an epidermoid cyst and an ultimobranchial cyst)—lesions that are usually considered incidental. While no toxic (metal or otherwise) etiology could be ascertained for these lesions, the incidence of retained embryologic remnants seemed high. A number of xenobiotics are known to be endocrine-disruptors, and the potential for such an etiology among these seals should be examined further. Lipofuscin deposition was ubiquitous among all three species examined histologically. Lipofuscin was most prevalent in hepatocytes, but also commonly was observed in various other tissue and cell types, especially in cardiac and skeletal myocytes, and in uriniferous tubular epithelial cells. The third portion of this study employed autometallographic (AMG) development of light microscopic tissue sections to amplify and localize deposition of inorganic Hg in liver and kidney of beluga and bowhead whales. No staining occurred among bowhead tissues, confirming the extremely low concentration of Hg determined through chemical analyses. In beluga kidney sections, AMG granules were seen throughout the uriniferous tubular epithelium, showing that Hg deposits throughout the nephric tubule, and not solely in the proximal tubular epithelium. In liver tissue, AMG granules were deposited primarily in periportal regions among whales with lower hepatic Hg burdens. In addition to periportal deposition, AMG granules were observed in pericentral and mid-zonal regions in the belugas sampled that had higher liver Hg concentrations (generally older animals). Granules were densely concentrated in stellate macrophages, especially near portal triads. Granules also were distributed in hepatocellular cytoplasm, generally concentrated toward the bile cannalicular domain of the cell. Granules were discrete, potentially indicating that Hg was confined within lysosomes. These observations suggested that inorganic Hg deposits initially in periportal regions of young animals, with subsequent accumulation occurring pericentrally, and finally, midzonally as the whales age. Computer-assisted densitometric analysis was used for semi-quantitative evaluation of AMG staining intensities. These AMG staining intensities were well correlated with concentrations of Hg determined via chemical analysis. Areas with AMG-staining were identified and compared with location of lipofuscin in the same field, visualized with fluorescent microscopy. While AMG granules and lipofuscin deposits sometimes were co-localized, they more often were not. In addition, abundant lipofuscin deposition was seen in livers of younger belugas with little to no Hg-catalyzed AMG staining. Also, lipofuscin concentrated predominantly in pericentral regions. These observations suggested that in the healthy marine mammals of this study, marked hepatic lipofuscin deposition most often occurred independently of Hg accumulation. Consequently, hepatic lipofuscin is likely to be a poor indicator of Hg-induced damage in belugas. The abundant lipofuscin deposition in livers of marine mammals was interpreted as most likely denoting a heightened exposure to oxidative stress that is probably inherent to a marine mammalian existence. These oxidative stressors may include a diet high in polyunsaturated fatty acids (PUFAs), alternating hypoxia and abundant oxygenation, and periodic bouts of anorexia associated with migration.
We conducted gamma spectrometric analyses on more than 200 arctic marine mammal tissue samples. These samples were primarily provided by subsistence hunters from northern Alaska, with a smaller number of samples from the Resolute region in Canada. The majority of samples (>90% ) had detectable levels of the anthropogenic radionuclide 137Cs, with a mean level observed in all samples of 0.67 Bq kg-1 dry weight ±0.81 (SD). Converted to wet weight, the mean was 0.21 Bq kg-1 ±0.19 SD. The median activity observed was 0.45 Bq kg-1 dry weight (0.18 Bq kg-1 wet weight) with a range from detection limits to 6.7 Bq kg-1dry weight (1.1 Bq kg-l wet weight). These findings confirm expectations that current anthropogenic gamma emitter burdens in marine mammals used in the North American Arctic as subsistence food resources are well below activities that would normally merit public health concern (~1000 Bq kg-1 wet weight). Some differences among species and tissues were observed. Beluga tissues had slightly higher mean burdens of 137Cs overall, and epidermis and muscle tissues in bowhead and beluga whales typically had higher burdens than other tissues analyzed. Low levels of the neutron activation product l08mAg (half-life 418 yr.), probably bioaccumulated from bomb fallout sources, were observed in 16 of 17 beluga livers analyzed, but were not found in any other tissues of beluga or in any other species sampled. A subset of 39 samples of various tissues was analyzed for the alpha and beta emitters 239,240Pu and 90Sr. Plutonium levels were near the threshold of detectability (~0.1 Bq kg-1 dry weight) in 6 of the 39 samples; all other samples had no detectable plutonium. A detectable level of 90Sr (10.3 ±1.0 Bq kg-1 dry weight) was observed in only one of the 39 samples analyzed, a bowhead epidermis sample. Although the accumulation of 108mAg has not been previously reported in any marine mammal livers, all of our analytical measurements indicate that only very low levels of anthropogenic radioactivity are associated with marine mammals harvested and consumed in the North American Arctic.
Moose (Alces alces) found dead (FD) and hunter-killed (HK) in 1995 on the north slope of Alaska (Colville River drainage) were evaluated for heavy metal and mineral status. Compared to previous reports for moose and domestic cattle, and data presented here from Alaska moose outside the Colville River area, levels of copper (Cu) were determined to be low in hoof, hair, liver, kidney, rumen contents, and muscle for these north slope moose. Iron (Fe) was low in muscle as well. These findings, in conjunction with evidence of poor calf survival and adult mortality prompted investigation of a mineral deficiency in moose (serum, blood, and hair) captured in the spring of 1996 and 1997. Captured males had higher Ca, Zn and Cu levels in hair than captured females. Female moose hair samples were determined to be low (deficient) in Cu, Ca, Fe, and Se with mean levels (ppm) of 2.77, 599.7, 37.4, and 0.30, respectively. Serum Cu level was low, and to a lesser degree Zn was deficient as well. Whole blood (1997 only) was marginally deficient in Se and all animals were deficient in Cu. Based on whole blood, sera and hair, Cu levels were considered low for moose captured in spring 1996 and 1997 in the Colville River area as compared to published data and other populations evaluated in this study. Low levels of ceruloplasmin activity support this Cu deficiency theory. Evidence indicates that these moose are deficient in Cu and other minerals; however, the remote location precluded sufficient examination of animals to associate this apparent deficiency with direct effects or lesions. Renal levels of Cd increased with age at expected levels.
Establish a benchmark to gauge the efficacy of legislation restricting the use of marine antifoulants containing TBT on the Pacific coast of the US
Polybrominated diphenyl ethers (PBDEs) are persistent and lipophilic compounds used as flame retardants in electronic equipment, plastic material and synthetic fibbers among other things. The PBDEs are mainly used as Deca-BDE and Bromokal 70-5DE, a mixture of tetra-, penta- and hexa-BDE. Due to its chemical and physical properties PBDEs, especially TeBDEs, tend to bioaccumulate. PBDEs were first reported in sediments in USA, and in fish from a Swedish river. More recently PBDEs have also been reported in seals, birds, mussels, whales and humans. In this study an SFE-method for rapid analysis of PBDEs in marine mammals was developed. This method was used to determinate the concentrations of these environmental pollutants in Pilot Whale samples caught in the Faroe Islands, Beluga Whales from the Arctic and Polar Bears from Svalbard. Using this method several PBDEs were analysed in the different species. In addition methoxylated PBDEs (Me-O-PBDE) were identified by interpretation of the different mass spectra’s. Of the 209 theoretical possible congeners only a few PBDE seem to accumulate in the environment. Accumulation of PBDE is related to the different chemical properties of the molecule. With the help of multivariate characterisation of a compound class using semi-empirical molecular orbital calculations, literature data and actual experimental measurements, the behaviour of PBDE in the environment can be modelled and predicted. Such models are essential in order to gain more insight in the behaviour of PBDE in the environment.
Our broad area of enquiry is the role of polar regions in the global energy and water cycles, and the atmospheric, oceanic and sea ice processes that determine that role. The primary importance of our investigation is to show how these polar processes relate to global climate.
The Barrow Observatory is a two-person manned station from which hundreds of measurements are made that are related to factors in the atmosphere that affect climate change and ozone depletion. In addition to a wide spectrum of NOAA programs, the Barrow Observatory is host to a dozen cooperative programs with other agencies and universities.
Research in the NOAA OAR Arctic Research Office Activities Supported by Base Funds in FY2000 Joint IARC/CIFAR Research In FY2000, the NOAA Arctic Research Office developed a partnership with the National Science Foundation and the International Arctic Research Center at the University of Alaska to conduct a research program focused on climate variability and on persistent contaminants in the Arctic. This partnership resulted from a unique confluence of mutual interest and unexpected funding that NSF chose to obligate through NOAA because of NOAA's on-going joint programs at the University of Alaska. NSF anticipates establishing its own institutional arrangement with the University of Alaska in the future. The research initiated in FY2000 focused on 5 climate themes and 1 contaminant theme, with several specific topics associated with each: A. detection of contemporary climate change in the Arctic changes in sea ice role of shallow tundra lakes in climate comparison of Arctic warming in the 1920s and the present variability in the polar atmosphere dynamics of the Arctic Oscillation downscaling model output for Arctic change detection long-term climate trends in northern Alaska and adjacent Seas B. Arctic paleoclimate reconstructions drilling in the Bering land bridge Arctic treeline investigation Mt. Logan ice core test models to simulate millennial-scale variability C. Atmosphere-ice-land-ocean interactions and feedbacks impact of Arctic sea ice variability on the atmosphere model-based study of aerosol intrusions into the Arctic international intercomparison of Arctic regional climate models reconstruction of Arctic ocean circulation intercomparison of Arctic ocean models Arctic freshwater budget variation in the Arctic vortex role of Arctic ocean in climate variability Arctic Oscillation and variability of the upper ocean D. Arctic atmospheric chemistry assessment of UV variability in the Arctic Arctic UV, aerosol, and ozone aerosols in the Finnish Arctic inhomogeneities of the Arctic atmosphere aerosol-cloud interactions and feedbacks Arctic haze variability E. Impacts and consequences of global climate change on biota and ecosystems in the Arctic linking optical signals to functional changes in Arctic ecosystems marine ecosystem response to Arctic climate changes faunal succession in high Arctic ecosystems long-term biophysical observations in the Bering Sea cryoturbation-ecosystem interactions predicting carbon dioxide flux from soil organic matter F. Contaminant Sources, Transport, Pathways, Impacts using apex marine predators to monitor climate and contamination change trends in atmospheric deposition of contaminants assessment of data on persistent organic pollutants in the Arctic paleorecords of atmospheric deposition derived from peat bog cores toxicological effects of bio-accumulated pollutants Under these themes, 45 research projects were initiated that will continue into 2001. The support for these projects totals $8 million over two years, of which only $1 million comes from NOAA. This tremendous leverage cannot be expected to continue; however the Arctic Research Office will continue its interactions with the International Arctic Research Center and seek collaborative efforts whenever possible. Arctic Climate Impact Assessment The United States has agreed to lead the other seven Arctic countries to undertake an Arctic Climate Impact Assessment (ACIA). This assessment will culminate in 2002 with a peer-reviewed report on the state of knowledge of climate variability and change in the Arctic, a set of possible climate change scenarios, and an analysis of the impacts on ecosystems, infrastructure, and socio-economic systems that might result from the various climate change scenarios. NOAA and NSF will provide support in FY2000, with the ARO providing early support and leadership for planning the ACIA. Scientific Planning and Diversity The Arctic Research Office will support scientific planning, information dissemination, and NOAA's diversity goals through workshops and other activities. An international conference on Arctic Pollution, Biomarkers, and Human Health will be held in May, 2000. The conference is being organized by the National Institutes of Environmental Health Sciences, with co-sponsorship by NSF and the Arctic Research Office. Research planning activities are being supported that will lead to future program activities related to climate variability and change and to impacts from contamination of the Arctic. The Study of Environmental Arctic Change (SEARCH) is being planned on an interagency basis, with the Arctic Research Office providing input for NOAA. An Alaskan Contaminants Program (ACP) is under development, with leadership coming from organizations within the state of Alaska. To accelerate the flow of minorities into scientific fields of interest to NOAA, the Arctic Research Office will undertake an effort in conjunction with Alaskan Native organizations that will encourage young Native students to obtain degrees in scientific fields. Outlook to FY2001 The Arctic Research Office will use resources available on FY2001 to begin implementation of the interagency Arctic climate science plan "Study of Environmental Arctic Change" (SEARCH). The NOAA/ARO role in SEARCH will involve long-term observations of the ocean, atmosphere and cryosphere, improved computer-based modeling of climate with an emphasis on the Arctic, and diagnostic analysis and assessment of climate data and information from the Arctic. Funds available in FY2001 will permit planning and limited prototype observation and modeling activities. The role of the NOAA/ARO in the Alaska Contaminants Program will become during the last half of FY2000, and some initial activities may be undertaken in FY2001. In addition, the NOAA/ARO will continue its partial sponsorship of the Arctic Climate Impact Assessment, being pursued on an international basis with the involvement of all 8 Arctic countries. It is anticipated that the ARO will provide support to experts to produce portions of the draft state-of-knowledge report during FY2001 and conduct one or more review workshops.
Our central geophysical objective is to determine how sea ice and the polar oceans respond to and influence the large-scale circulation of the atmosphere. Our primary technical objective is to determine how best to incorporate satellite measurements in an ice/ocean model.
To observe the temperature/salinity structure of the Arctic Ocean along cross-Arctic transects aboard U.S. nuclear submarines in the SCICEX program.
To develop a long-range (ca. 30-day) AUV to deploy under the Arctic pack ice to measure and monitor ocean variables.
The program provides logistics for ongoing research projects in Greenland, Alaska, and the Arctic Ocean. Logistics capabilities and platforms provided for research projects include: icebreakers, other ships, remote field camps, heavy-lift aircraft, and field stations (e.g. Toolik Field Station and Summit Greenland Station). The program also supports research projects at Long-Term Observatories and development of remote, autonomous instruments.
The project consists of two parts: the generation of a data set of sea ice extents and areas, and associated scientific analyses. The objective of the first part is to produce a 30-year, research quality sea ice data set for climate change studies. The data set will build on an existing 18-year data set derived from satellite passive-microwave observations and currently archived at the National Snow and Ice Data Center in Boulder, CO. We will extend this data set by using historical data from the 1970's from the National Ice Center and new data from DMSP Special Sensor Microwave Imagers and the upcoming EOS-PM Advanced Microwave Scanning Radiometer. These data sets will be cross-calibrated to ensure a consistent 30-year data set following methods developed earlier and based on matching the geophysical parameters during periods of sensor overlap. The principal products will be Arctic and Antarctic sea ice extents and areas, derived from sea ice concentration maps. The second part of the proposal will center on the analysis and use of the 30-year data set. The science objectives are (1) to define and explain the hemispheric, regional, seasonal, and interannual variabilities and trends of the Arctic and Antarctic sea ice covers and (2) to understand any observed hemispheric asymmetries in global sea ice changes. Hemispheric sea ice cover asymmetries have been found in the existing 18-year record and have also been suggested from some model experiments simulating future conditions assuming a gradual increase in atmospheric CO2. We will examine the proposed 30-year record to determine the degree and nature of the hemispheric asymmetry in it and to place the sea ice observations in the context of other climate variables through comparisons with simulations from the NOAA Geophysical Fluid Dynamics Laboratory and Hadley Centre climate models.
Principal areas of activity are directed to: - observations of changes in the arctic system important to climate change, including the state of the atmosphere, ocean, sea ice and ecosystems; - studies of arctic system processes that may produce significant feedbacks tothe global system; - development of models based on process studies to predict the consequences of global change for the arctic environment and to predict the global consequences of changes occurring within the Arctic; - compilation of a record of past environmental variability; - coupling of paleoclimatic and modern observational records to improve quantitative reconstructions of past conditions for better evaluation of modeling results.
Observing the temperature structure of the Arctic Ocean along a transect from Franz Josef Land to ALERT, Canada, using acoustic tomography.