Eco-Light

Description

The Arctic is warming more than twice as fast as any other region of our planet. This warming has led to quantifiable changes right across the Arctic; land, ocean and atmosphere. The most dramatic changes are those associated with Arctic sea ice whose extent has decreased by over 50% in the last three decades. The Arctic is no longer a region dominated by a thick multi-year ice (MYI); it is now a regime controlled by thinner, more dynamic, first year ice (FYI). Moreover, the Arctic is experiencing a shift from a year-round sea-ice cover to a seasonal regime. In fact complex computer models predict that the Arctic Ocean is on track to become mostly ice free in summer within a few decades, if not earlier.

These changes have important implications for the Arctic marine ecosystem since its functioning is mainly driven by the seasonality and the physical properties of the sea ice. Our understanding of the functioning of the Arctic marine ecosystem has been overwhelmingly derived from a MYI setting, rather than the FYI dominated Arctic of recent years. As a result, our current state of knowledge of these processes and the validity of many of the parameterisations presently embedded in computer models become more questionable. Light is one of the critical drivers of primary production in and under sea ice by acting as a trigger for sea-ice algae and phyotplankton blooms. Recent studies revealed that that the transition from MYI to FYI ice cover corresponds to an increase of 200% in light transmittance into the upper ocean. Therefore, if we are to understand and predict ecosystem function in this ‘new Arctic’, we must understand and correctly parameterise the light climate under this new FYI environment we find ourselves in today, and for the foreseeable future. To do this correctly we need a holistic approach that seamlessly brings biology, optics, sea ice and ocean physics, together with satellite remote sensing and cutting-edge modelling.

Our programme, Eco-Light does this by utilising the modelling and observational expertise of the United Kingdom and Germany, along with collaborations with South Korea and Canada, to better understand the influence of changing Arctic sea ice and snow conditions on oceanographic properties and ecosystem function.

Objectives

Our overall goal is to demonstrate how the Arctic ecosystem may change in the future, because of changes in timing and duration of primary production events and grazing habits of zooplankton. We will evaluate how these ecosystem functions mirror changing snow and sea ice regimes in the Arctic Ocean, as they continue their transition from thick MYI to thinner and more dynamic FYI.  The shift from MYI to FYI has consequences on the radiative transfer, as well as for changes in the phenology of food availability, i.e. phytoplankton blooms and sea-ice algae. To quantify the biological response to this changing Arctic, we need to better describe the complexity of the coupled physical-biological system, especially over an annual cycle. Changes in the light field under the sea ice is one of the drivers that affects large-scale ecosystem structure and biogeochemical functioning of the Arctic marine environment.

With this information in mind we have the following two sub-objectives:

1. The determination of how the distribution of light/radiation relevant for the biology of the sea ice matrix varies on the pan-Arctic scale, and its dependence on snow thickness, sea ice type and state and season.
2. The upscaling of the observed/investigated light regimes in and below the sea-ice matrix to the pan-Arctic scale for improving numerical simulations of the sympagic ecosystem and prediction of its changes.

Taken as a whole our project will improve our understanding of how changes in the physical environment (snow, sea ice and ocean) affect the large-scale ecosystem functioning of the Arctic marine environment, both today and under different IPCC emission scenarios.

Region

To predict the consequences of changing sea ice for Arctic ecosystem function, it is critical that we understand the links between sea ice, upper ocean physics and ecosystem dynamics in a region that has witnessed some of the greatest changes. For this reason we will perform a focused set of multidisciplinary autonomous measurements in the Beaufort/Chukchi Sea.  We will deploy our scientific instrumentation during two late season cruises, September 2018 and 2019, of the Korean icebreaker Araon.

Methodology

Since satellites sensors cannot ‘see through’ the sea ice or the ocean, the response of Arctic primary production (and zooplankton) to changes in sea ice and snow properties can only be determined with continuous in-situ monitoring of algae and phytoplankton stocks, together with the main physical drivers affecting their phenology: under-ice light field, sea ice and snow properties, temperature and salinity of the ocean surface, nutrients and mixed layer depth.  To do this Eco-Light has developed a holistic approach that seamlessly brings together autonomous robotic observations of sea ice, snow and ocean properties (physical and biological) together with remote sensing and cutting-edge modelling. Our interdisciplinary project aims to observationally constrain and improve the parameterisations of processes of light transmission in this ‘new’ Arctic and to validate and improve parameterisations describing the ecosystem functioning. To work efficiently we have broken these down into manageable work packages (WPs), indicating the linkages between each WP. The first three WPs address each of the hypotheses mentioned above, whilst the final WP, WP4, is related to the project management and communication between project partners, other UK and German funded projects, KOPRI, and the funding agencies. Our interlinked WPs are entitled:

• WP 1: Integrated bio-physical observations on local and pan-Arctic scale
• WP 2: Understanding the seasonality of light-driven processes in the sea ice ecosystem
• WP3 Simulating and upscaling the biophysical system to pan-Arctic scale
• WP4: Project Governance

Eco-Light plays to the Arctic marine scientific strengths of the UK, Germany and Korea. As a result our devised strategy takes advantage of each country’s strength, and applies them to one of the fastest changing regions of the Arctic. All datasets collected by Eco-Light are freely accessible via dedicated websites located at AWI and BAS.