Karen Junge

Senior Oceanographer

PSC Department


Bonnie Light

Chair, Polar Science Center

Senior Principal Physicist

PSC Department


Affiliate Associate Professor, Atmospheric Sciences

Monica Orellana

Principal Oceanographer

Polar Science Center

Carie Frantz

Research Associate

PSC Department


Shelly Carpenter

Research Collaborator

PSC Department


Extreme Summer Melt

Assessing the Habitability and Physical Structure of Rotting First-year Arctic Sea Ice

We are studying an ice type that hasn't been looked at before. We call it rotten ice. It's heavily melted sea ice.

The ice harbors micro-organisms that produce polymer-like substances. These polymers may actually affect the physics and structure of the melting sea ice.

Sea ice cover in the Arctic during summer is shrinking and thinning. The melt season is lengthening and the prevalence of "rotten" sea ice is increasing.

A multidisciplinary team of researchers is making a series of three monthly (May, June, and July) expeditions to Barrow, AK. They are measuring the summertime melt processes that transform the physical properties of sea ice, which in turn transform the biological and chemical properties of the ice habitat.

Sea ice at the beginning of the melt season has been studied extensively. So for the May trip to Barrow, the team is using standard, accepted methods to take detailed measurements of the ice and microbial communities within it.

When the team returns later in the melt season, they will be exploring uncharted territory — their methods have never been applied to severely melted, or "rotten", sea ice.


Summertime melt processes act to transform the microstructure of sea ice, and these changes in the microstructure transform large-scale biological, chemical, and physical properties of the ice.

Polymer gels help preserve ice integrity, providing an important link between algae, bacteria and structural integrity. Sea ice is expected to become more "rotten" when included polymer gels are less prevalent and are composed of smaller sizes.

Science Questions

  • What are the physical (salinity, temperature, ice density, and permeability), microstructural (crystal size, shape, brine pocket number densities, channel diameters and thickness) and optical (spectral albedo) properties of rotten ice?
  • What are the microbial abundances, activities, productivity and diversity in rotten ice?
  • What are the predominant phylotypes in rotten ice and can we predict the dominant species in a future warmer ice–icean system?
  • How do physical and microbiological characteristics of rotten ice relate?
  • How does the melting process affect microbial and microstructural characteristics of the ice?
  • What is the role of polymers in the interdependence between ice stability and microbial life?
  • Will the ice become more rotten when less and/or smaller size polymer gels are present?
  • How important could this ice type be for the Arctic summertime ecosystem, how important for carbon budgets?