• Le 13 March 2019
    Unknown label
    Faculté des Sciences - Amphi 111
  • 12h

Dr. Christopher Williamson is invited by the team Remote sensing & benthic ecology. He will give a talk entitled:

Black and Bloom: the impact of microalgae on darkening and melt of the Greenland Ice Sheet


Melt of the Greenland Ice Sheet (GrIS), the second largest body of ice in the world, is the single largest contributor to global sea level rise. Accelerating surface melt since the early 1990s has been accompanied by long-term declines in GrIS surface albedo, i.e. surface darkening, particularly along the western margin of the ice sheet in the so-called ‘dark-zone’. Given that albedo is the dominant control of ice surface melt, processes that serve to darken the GrIS hold significant potential to drive melt, with global consequences.
groenland
  • Colourful ice algal blooms surround the science camp on the surface of the Greenland Ice Sheet (left). Surface ice is full of pigmented algae and particles (top right), with algae showing significant pigmentation (bottom right) to protect against excessive irradiance.

Here I will present my work as part of the UK NERC funded Black & Bloom project that was established to determine the relative importance of dark particles (black) and microorganisms (bloom) on surface darkening and melt of the GrIS. Over the past 3 years I have led field expeditions across the western ablation zone of the GrIS to constrain dynamics in ‘ice-algal’ blooms that occur in surface ice during summer melt periods. These assemblages of heavily pigmented Streptophyte microalgae are able to thrive and bloom in surface ice when liquid water is available, despite the extreme abiotic conditions that prevail. I’ll present the approach taken by the Black & Bloom team to constrain drivers of surface darkening, with emphasis on my work concerning ice algal ecophysiology, and constraining temporal/spatial patterning in bloom progression.

Dr. Christopher Williamson is a Postdoctoral Research Associate from Bristol University
williamson