Periodic Reporting for period 4 - DEEP PURPLE (DEEP PURPLE: darkening of the Greenland Ice Sheet)
Reporting period: 2023-10-01 to 2025-03-31
The stability of the Greenland Ice Sheet (GrIS) is a threat to coastal communities worldwide. We have changed our understanding of why it darkens during the melt season, becoming increasingly deep purple due to pigmented ice algal blooms in the ice surface, producing more melt and accelerating the GrIS towards its tipping point, and accelerating sea level rise.
The next step jump in our understanding of biological darkening will be provided by DEEP PURPLE, which will establish the factors that control ice algal blooms. These factors are essential for the modelling of future melting, which require a process-based understanding of blooming. DEEP PURPLE will quantify the synergies between the biology, chemistry and physics of ice algae micro-niches in rotting, melting ice, and examine the combination of factors which stabilise them.
State-of-the-science analytical and observational methods will be employed to characterise the complex mosaic of wet ice habitats, dependent on factors such as the hydrology, nutrient status, particulate content and light fields within these continually evolving ice-water-particulate-microbe systems. We will quantitatively assess why and how the fine light mineral dust particulates contained within the melting ice amplify the growth of ice algae.
The particulate content and composition of different layers in the GrIS is dependent on age, and so the algae that the melting ice can support may fundamentally change over time. We look back to understand if the ice biome has changed through the Anthropocene via analyse of fjord sediments. The first draft genome of ice algae will show their key adaptations to glacier surface habitats. DEEP PURPLE looks forward by providing the critical field data sets and conceptual models of ice algal growth that will facilitate the next generation of predictive models of sea level rise due to biologically enhanced melting of the GrIS.
DEEP PURPLE aims to investigate the physical and microbial processes that darken the Greenland Ice Sheet (GrIS) and accelerate sea level rise, with the following principal objectives:
1. To make contemporaneous measurements of the biological, geochemical and physical factors effecting surface darkening at sites across the GrIS, including the relatively frigid north of the Dark Zone, towards the interior of the ice sheet and at sites in the relatively mild south.
2. To gain process information on the limits and stimulation of darkening from a southern site, and the potential for further darkening from the northern and the interior areas of the GrIS.
3. To examine interactions between ice algae, mineral dust (including black carbon) concentrations, and test their relative importance and synergies in surface darkening.
The next step jump in our understanding of biological darkening will be provided by DEEP PURPLE, which will establish the factors that control ice algal blooms. These factors are essential for the modelling of future melting, which require a process-based understanding of blooming. DEEP PURPLE will quantify the synergies between the biology, chemistry and physics of ice algae micro-niches in rotting, melting ice, and examine the combination of factors which stabilise them.
State-of-the-science analytical and observational methods will be employed to characterise the complex mosaic of wet ice habitats, dependent on factors such as the hydrology, nutrient status, particulate content and light fields within these continually evolving ice-water-particulate-microbe systems. We will quantitatively assess why and how the fine light mineral dust particulates contained within the melting ice amplify the growth of ice algae.
The particulate content and composition of different layers in the GrIS is dependent on age, and so the algae that the melting ice can support may fundamentally change over time. We look back to understand if the ice biome has changed through the Anthropocene via analyse of fjord sediments. The first draft genome of ice algae will show their key adaptations to glacier surface habitats. DEEP PURPLE looks forward by providing the critical field data sets and conceptual models of ice algal growth that will facilitate the next generation of predictive models of sea level rise due to biologically enhanced melting of the GrIS.
DEEP PURPLE aims to investigate the physical and microbial processes that darken the Greenland Ice Sheet (GrIS) and accelerate sea level rise, with the following principal objectives:
1. To make contemporaneous measurements of the biological, geochemical and physical factors effecting surface darkening at sites across the GrIS, including the relatively frigid north of the Dark Zone, towards the interior of the ice sheet and at sites in the relatively mild south.
2. To gain process information on the limits and stimulation of darkening from a southern site, and the potential for further darkening from the northern and the interior areas of the GrIS.
3. To examine interactions between ice algae, mineral dust (including black carbon) concentrations, and test their relative importance and synergies in surface darkening.
To date, field campaigns have been undertaken at four locations in Greenland (https://www.deeppurple-ercsyg.eu/fieldwork(opens in new window)) with work concentrated on the life cycles of snow and glacier ice algae, and the impact of the increased frequency and severity of rainfall and storms. Lab work focussed on developing novel ways to characterise the adsorption properties of glacier ice algae for use in radiative transfer models. Drone and remote sensing work characterised Dark Zone variability and change, both at present and looking as far back in satellite records as has been possible (to 1984).
Cultures have been established for algae living on the ice sheet surfaces in order to understand controls on the growth of snow and ice algae in their respective ice and snow habitats, which has permitted work on the genomics of ice algae and in-depth understanding of their life cycles to be undertaken.
We designed, tested and validated methods of how to collect and process on site ice cores cleanly (for microbial analyses) and tested and cross-confirmed best procedures for returning ice cores to the home lab without compromising the integrity of collected ice cores (i.e. avoid / minimize recrystallization of the ice).
Deep Purple has been able to characterise the activity, nutrient requirements and genome of glacier ice algae, using novel single-cell techniques (secondary ion mass spectrometry (SIMS), combined scanning electron microscopy, and single cell sorting). A range of experiments, together with the single-cell measurements, provided some vital data about nutrient controls, suggesting that glacial ice algae are not severely limited by macronutrients.
A number of techniques for the characterisation of organic molecules related to biological activity on ice surfaces have been used during the field campaigns, showing, for instance, that microbial communities on the ice surface are able to emit volatile organic carbon at the same order of magnitude as in tundra ecosystems. Furthermore, a significant fraction of the volatile organic carbon produced have been identified as anti-fungal metabolites. This information combined with the high rates of fungal parasitic infection on glacial algae demonstrate the chemical warfare that happens in microbial communities from the ice surface.
Cultures have been established for algae living on the ice sheet surfaces in order to understand controls on the growth of snow and ice algae in their respective ice and snow habitats, which has permitted work on the genomics of ice algae and in-depth understanding of their life cycles to be undertaken.
We designed, tested and validated methods of how to collect and process on site ice cores cleanly (for microbial analyses) and tested and cross-confirmed best procedures for returning ice cores to the home lab without compromising the integrity of collected ice cores (i.e. avoid / minimize recrystallization of the ice).
Deep Purple has been able to characterise the activity, nutrient requirements and genome of glacier ice algae, using novel single-cell techniques (secondary ion mass spectrometry (SIMS), combined scanning electron microscopy, and single cell sorting). A range of experiments, together with the single-cell measurements, provided some vital data about nutrient controls, suggesting that glacial ice algae are not severely limited by macronutrients.
A number of techniques for the characterisation of organic molecules related to biological activity on ice surfaces have been used during the field campaigns, showing, for instance, that microbial communities on the ice surface are able to emit volatile organic carbon at the same order of magnitude as in tundra ecosystems. Furthermore, a significant fraction of the volatile organic carbon produced have been identified as anti-fungal metabolites. This information combined with the high rates of fungal parasitic infection on glacial algae demonstrate the chemical warfare that happens in microbial communities from the ice surface.
We have produced the first harmonised satellite remote sensing data for albedo variations in the Dark Zone, from 1984 to 2020 (https://github.com/fsn1995/Remote-Sensing-of-Albedo(opens in new window) Feng et al, 2023, doi: 10.1017/jog.2023.11). There has been widespread community uptake of the BIOSNICER GO radiative transfer model (https://github.com/jmcook1186/BioSNICAR_GO(opens in new window)) the state of the science model for calculating the impact of both organic and inorganic particulates on ice melt. New methodology has been developed for measuring the adsorption capacity of glacier ice algal cells, providing new fundamental data for use in radiative transfer models. Our work on nutrient chemistry shows that future expansion of the Dark Zone is unlikely to be macro-nutrient limited, removing one of the key hurdles that confounds widescale darkening of the ice sheet in a warming climate.
We are close to publishing a full genome of the glacier algae and to provide in-depth understanding of their characteristics and evolutionary traits that allow them to survive and thrive on ice surfaces. This will have a high impact in the subject area, considering that the glacier ice algae do not only inhabit the Greenland Ice Sheet, but glaciers worldwide.
We have designed, tested and validated new methods to collect, preserve, process and analyse the very low levels of organic carbon contents in the melted snow and ice by avoiding any use of plastics in the procedures. Using a similar approach, we also optimized the extraction and analyses of the complex carbon species contained in all filtered particulates by developing and optimising a series of extraction and analyses protocols for high-resolution mass spectrometric analyse of all organic compounds (incl. pigments, metabolites and carbon species) in all cases to very low levels.
The understanding of the nutrient requirements from single cell nutrient analysis is allowing refinement of the culturing work that will allow for the next generation of laboratory experiments with glacier ice algae. This would include, for example, understanding of how ice algae interact with other members of the microbial community, mechanisms for production of photo-protective pigments (that ultimately impact on albedo), and their adaptation mechanisms to freeze-thawing conditions.
We are close to publishing a full genome of the glacier algae and to provide in-depth understanding of their characteristics and evolutionary traits that allow them to survive and thrive on ice surfaces. This will have a high impact in the subject area, considering that the glacier ice algae do not only inhabit the Greenland Ice Sheet, but glaciers worldwide.
We have designed, tested and validated new methods to collect, preserve, process and analyse the very low levels of organic carbon contents in the melted snow and ice by avoiding any use of plastics in the procedures. Using a similar approach, we also optimized the extraction and analyses of the complex carbon species contained in all filtered particulates by developing and optimising a series of extraction and analyses protocols for high-resolution mass spectrometric analyse of all organic compounds (incl. pigments, metabolites and carbon species) in all cases to very low levels.
The understanding of the nutrient requirements from single cell nutrient analysis is allowing refinement of the culturing work that will allow for the next generation of laboratory experiments with glacier ice algae. This would include, for example, understanding of how ice algae interact with other members of the microbial community, mechanisms for production of photo-protective pigments (that ultimately impact on albedo), and their adaptation mechanisms to freeze-thawing conditions.