A5026266151- Arctic and Antarctic ice dynamics
- Climate change and permafrost
- Cryospheric studies and observations
- Climate variability and models
- Methane Hydrates and Related Phenomena
- Atmospheric and Environmental Gas Dynamics
- Geological Studies and Exploration
- Geology and Paleoclimatology Research
- Arctic and Russian Policy Studies
- Meteorological Phenomena and Simulations
- Oceanographic and Atmospheric Processes
- Tropical and Extratropical Cyclones Research
- Atmospheric chemistry and aerosols
- Hydrology and Watershed Management Studies
- Polar Research and Ecology
- Food Industry and Aquatic Biology
- Tree-ring climate responses
- Icing and De-icing Technologies
- Indigenous Studies and Ecology
- Marine and environmental studies
- Atmospheric Ozone and Climate
- Marine animal studies overview
- Geophysics and Gravity Measurements
- Marine and fisheries research
- Ocean Acidification Effects and Responses
University of Colorado Boulder
2014-2023
Cooperative Institute for Research in Environmental Sciences
2014-2023
National Snow and Ice Data Center
2010-2022
University of Colorado System
2000-2021
NOAA National Ice Center
2012-2021
Princeton University
2021
University of Alaska Fairbanks
2005-2018
The Ohio State University
2000-2018
University of Washington
2018
NOAA Pacific Marine Environmental Laboratory
2018
From 1953 to 2006, Arctic sea ice extent at the end of melt season in September has declined sharply. All models participating Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) show declining cover over this period. However, depending time window for analysis, none or very few individual model simulations trends comparable observations. If multi‐model ensemble mean series provides a true representation forced change by greenhouse gas (GHG) loading, 33–38% observed...
The sequence of extreme September sea ice extent minima over the past decade suggests acceleration in response Arctic cover to external forcing, hastening ongoing transition towards a seasonally open Ocean. This reflects several mutually supporting processes. Because extensive water recent Septembers, following spring is increasingly dominated by thin, first-year (ice formed during previous autumn and winter) that vulnerable melting out summer. Thinner turn fosters stronger summer ice-albedo...
A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing terrestrial changes summer albedo contribute substantially recent high-latitude warming trends. Pronounced Alaska correlates with a lengthening of the snow-free season has increased atmospheric heating locally by about 3 watts per square meter decade (similar magnitude regional expected over multiple decades...
Linear trends in arctic sea-ice extent over the period 1979 to 2006 are negative every month. This ice loss is best viewed as a combination of strong natural variability coupled ice-ocean-atmosphere system and growing radiative forcing associated with rising concentrations atmospheric greenhouse gases, latter supported by evidence qualitative consistency between observed those simulated climate models same period. Although large scatter individual model simulations leads much uncertainty...
Abstract. Rises in surface and lower troposphere air temperatures through the 21st century are projected to be especially pronounced over Arctic Ocean during cold season. This amplification is largely driven by loss of sea ice cover, allowing for strong heat transfers from ocean atmosphere. Consistent with observed reductions extent, fields both NCEP/NCAR JRA-25 reanalyses point emergence surface-based last decade.
The rapid retreat and thinning of the Arctic sea ice cover over past several decades is one most striking manifestations global climate change. Previous research revealed that observed downward trend in September extent exceeded simulated trends from models participating World Climate Research Programme Coupled Model Intercomparison Project Phase 3 (CMIP3). We show here as a group, contributing to CMIP5 are more consistent with observations satellite era (1979–2011). Trends ensemble members...
Daily station data from U.S. Department of Agriculture snowpack telemetry (SNOTEL) archives through the 1995/1996 season are used to examine climatic characteristics snow water equivalent (SWE) for mountainous western United States and linkages with precipitation (PRE) temperature. Quality control procedures were developed screen outliers in each variable. SWE April 1 at SNOTEL sites compares favorably colocated course values. Regional differences seasonal cycle discussed terms winter‐half...
A summary is presented of the Surface Heat Budget Arctic Ocean (SHEBA) project, with a focus on field experiment that was conducted from October 1997 to 1998. The primary objective work collect ocean, ice, and atmospheric datasets over full annual cycle could be used understand processes controlling surface heat exchanges—in particular, ice–albedo feedback cloud–radiation feedback. This information being improve formulations arctic ice–ocean–atmosphere in climate models thereby simulations...
This paper synthesizes our understanding of the Arctic's large‐scale freshwater cycle. It combines terrestrial and oceanic observations with insights gained from ERA‐40 reanalysis land surface ice‐ocean models. Annual mean input to Arctic Ocean is dominated by river discharge (38%), inflow through Bering Strait (30%), net precipitation (24%). Total export North Atlantic transports Canadian Archipelago (35%) via Fram as liquid (26%) sea ice (25%). All terms are computed relative a reference...
Output from a cyclone detection and tracking algorithm, applied to twice-daily sea level pressure (SLP) fields for the period 1966–93, is used examine characteristics of activity associated with locus mean Icelandic low (IL), variability during extremes North Atlantic oscillation (NAO), recent changes in relation circulation over Northern Hemisphere. Cyclone events within climatological IL display modest seasonal cycle winter maximum. However, systems are considerably deeper than their...
Arctic sea ice declined rapidly to unprecedented low extents in the summer of 2007, raising concern that may be on verge a fundamental transition toward seasonal cover. extent typically attains maximum March and minimum September. Over course modern satellite record (1979 present), has significantly all months, with decline being most pronounced By mid‐July it was clear new would set during 2007.
One of the hypothesized effects global warming from increasing concentrations greenhouse gases is a change in frequency and/or intensity extratropical cyclones. In this study, winter frequencies and intensities cyclones Northern Hemisphere for period 1959–97 are examined to determine if identifiable trends occurring. Results indicate statistically significant decrease midlatitude cyclone increase high-latitude frequency. addition, storm has increased both high midlatitudes. The changes...
September Arctic sea ice extent over the period of satellite observations has a strong downward trend, accompanied by pronounced interannual variability with detrended 1 year lag autocorrelation essentially zero. We argue that through combination thinning and associated processes related to warming climate (a stronger albedo feedback, longer melt season, lack especially cold winters) trend itself is steepening. The manifests both inherent large in summer atmospheric circulation patterns...
Abstract Hydrologic cycle intensification is an expected manifestation of a warming climate. Although positive trends in several global average quantities have been reported, no previous studies documented broad across elements the Arctic freshwater (FWC). In this study, authors examine character and quantitative significance changes annual precipitation, evapotranspiration, river discharge terrestrial pan-Arctic over past decades from observations suite coupled general circulation models...
Satellite passive microwave observations document an overall downward trend in Arctic sea ice extent and area since 1978. While the record minimum observed September 2002 strongly reinforced this trend, extreme minima were again 2003 2004. Although having three years a row is unprecedented satellite record, attributing these recent trends extremes to greenhouse gas loading must be tempered by recognition that cover variable from year response wind, temperature oceanic forcings.
Changes in active layer thickness (ALT) over northern high‐latitude permafrost regions have important impacts on the surface energy balance, hydrologic cycle, carbon exchange between atmosphere and land surface, plant growth, ecosystems as a whole. This study examines 20th century variations of ALT for Ob, Yenisey, Lena River basins. is estimated from historical soil temperature measurements 17 stations (1956–1990, basin only), an annual thawing index based both air data (1901–2002)...
Projections of polar bear ( Ursus maritimus ) sea ice habitat distribution in the basin during 21st century were developed to understand consequences anticipated reductions on populations. We used location data from satellite‐collared bears and environmental (e.g., bathymetry, distance coastlines, ice) collected 1985 1995 build resource selection functions (RSFs). RSFs described habitats that preferred summer, autumn, winter, spring. When applied independent 1996 2006, consistently...
As the Arctic continues to warm faster than rest of planet, evidence mounts that region is experiencing unprecedented environmental change. The hydrological cycle projected intensify throughout twenty-first century, with increased evaporation from expanding open water areas and more precipitation. latest projections sixth phase Coupled Model Intercomparison Project (CMIP6) point rapid warming sea-ice loss by year 2100 in previous projections, consequently, larger changes cycle. precipitation...