BLACK and BLOOM: variations in the albedo of the Greenland Ice Sheet as a result of interactions between microbes and particulates.

Lead Research Organisation: University of Sheffield
Department Name: Geography

Abstract

Concerns are growing about how much melting occurs on the surface of the Greenland Ice Sheet (GrIS), and how much this melting will contribute to sea level rise (1). It seems that the amount of melting is accelerating and that the impact on sea level rise is over 1 mm each year (2). This information is of concern to governmental policy makers around the world because of the risk to viability of populated coastal and low-lying areas. There is currently a great scientific need to predict the amount of melting that will occur on the surface of the GrIS over the coming decades (3), since the uncertainties are high. The current models which are used to predict the amount of melting in a warmer climate rely heavily on determining the albedo, the ratio of how reflective the snow cover and the ice surface are to incoming solar energy. Surfaces which are whiter are said to have higher albedo, reflect more sunlight and melt less. Surfaces which are darker adsorb more sunlight and so melt more. Just how the albedo varies over time depends on a number of factors, including how wet the snow and ice is. One important factor that has been missed to date is bio-albedo. Each drop of water in wet snow and ice contains thousands of tiny microorganisms, mostly algae and cyanobacteria, which are pigmented - they have a built in sunblock - to protect them from sunlight. These algae and cyanobacteria have a large impact on the albedo, lowering it significantly. They also glue together dust particles that are swept out of the air by the falling snow. These dust particles also contain soot from industrial activity and forest fires, and so the mix of pigmented microbes and dark dust at the surface produces a darker ice sheet. We urgently need to know more about the factors that lead to and limit the growth of the pigmented microbes. Recent work by our group in the darkest zone of the ice sheet surface in the SW of Greenland shows that the darkest areas have the highest numbers of cells. Were these algae to grow equally well in other areas of the ice sheet surface, then the rate of melting of the whole ice sheet would increase very quickly. A major concern is that there will be more wet ice surfaces for these microorganisms to grow in, and for longer, during a period of climate warming, and so the microorganisms will grow in greater numbers and over a larger area, lowering the albedo and increasing the amount of melt that occurs each year. The nutrient - plant food - that the microorganisms need comes from the ice crystals and dust on the ice sheet surface, and there are fears that increased N levels in snow and ice may contribute to the growth of the microorganisms. This project aims to be the first to examine the growth and spread of the microorganisms in a warming climate, and to incorporate biological darkening into models that predict the future melting of the GrIS.

References

1. Sasgen I and 8 others. Timing and origin of recent regional ice-mass loss in Greenland. Earth and Planetary Science Letters, 333-334, 293-303(2012).
2. Rignot, E., Velicogna, I., van den Broeke, M. R., Monaghan, A. & Lenaerts, J. Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise. Geophys. Res. Lett. 38, L05503, doi:10.1029/2011gl046583 (2011).
3. Milne, G. A., Gehrels, W. R., Hughes, C. W. & Tamisiea, M. E. Identifying the causes of sea-level change. Nature Geosci 2, 471-478 (2009).

Planned Impact

BLACK and BLOOM aims to make a major impact on the state of the science for melt prediction from the Greenland Ice Sheet. We are committed to contributing our experiences during the course of our project to the international community via IASC (International Arctic Science Committee). We will be disseminating our research results to the academic community also via publication in the top rated peer reviewed literature and international, national and local conference presentations. We will use the auspices of the Cabot Institute at the University of Bristol to bring our improved predictions of the rate of melting of the Greenland Ice Sheet to the attention of governmental and other policy makers. The Dark Snow Project, run by Project Partner Jason Box (GEUS), is well known to the public, and we will link our project web site to that of Dark Snow to aid outreach of our work to the general public. We will contribute to blogs and question and answer sessions when we are in the field via web links from Kangerlussuaq International Science Support (KISS). Hence, we aim to outreach to a broad spectrum of scientists, policy makers and the general public.

Publications

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Title BIOSNICAR: a physically-based model for characterising biological and non-biological impurity effects upon snow albedo 
Description This software allows prediction of spectral and broad bnd albedo of snow and ice contaminated with biological impurities for the first time. Previous versions were only capable of parameterising the effects of non-biological impurities (dust and black carbon). The main code is written in MATLAB2016B with ancilliary code written in Python3.5 
Type Of Technology Software 
Year Produced 2018 
Open Source License? Yes  
Impact Widespread uptake by practitioners. Tours through the code (training) were given on request at a major scientific meeting. 
URL https://github.com/jmcook1186/BioSNICAR
 
Description Article describing project in Science magazine 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact News feature "Meltdown" in Science (vol 355, issue 6327) by Eli Kintisch, February, 2017: (doi: 10.1126/science.355.6327.788)
Year(s) Of Engagement Activity 2017
URL http://science.sciencemag.org/content/355/6327/788
 
Description Radio 4 interview 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact 'Midweek' on Radio 4, 14th December 2016
Year(s) Of Engagement Activity 2016,2017
 
Description School visit (Lichfield) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact School visit: "Microbes, sunshine and ice", King Edward VI School, Lichfield, 28/2/17 by Dr Joe Cook
Year(s) Of Engagement Activity 2017
 
Description Teaching at School 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Policymakers/politicians
Results and Impact PDRA Dr Joe Cook visited Dane Court Grammar School to conduct 3 x Climate Change sessions (Yr 10, Yr 11, Yr13 Geography), 18/10/17.
Year(s) Of Engagement Activity 2018
 
Description Teaching in schools 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact PDRA Joe Cook visited St Laurence Junior School to contribute to "Extreme Earth" teaching sessions, 2 x 1 hr, Yr 6, 17/10/17
Year(s) Of Engagement Activity 2018
 
Description University Open Day presentation 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Black and Bloom research was used to present research environment and its interface with education at Sheffield University during its open days.
Year(s) Of Engagement Activity 2016