Negative feedback in the cold: ice retreat produces carbon sinks in Antarctica

1. Negative feedback in the cold: ice retreat produces carbon sinks in Antarctica By: L. S. Peck, D. K. A. Barnes, A. J. Cook, A. H. Fleming and A. Clarke Marshall Callahan Atmospheric Science

2. Overview • Purpose of Research • Importance of Research • Background Information • Data/Methods • Results • Conclusions • My Opinion • Questions

3. Purpose • Find out if loss of sea ice is counteracted by increase in marine ecosystems for global warming

4. Why is this Important? • Could Provide a new variable to take into account when estimating future global CO2 levels

5. Antarctica

6. Antarctica

7. Sea Ice • Can reflect around 70% of incoming Shortwave radiation (Acts as a negative feedback)

8. Melting Sea Ice • The melting of sea ice acts as a positive feedback for global warming • Less Sea Ice = Less reflected short wave radiation

9. Marine Ecosystems • All based off of phytoplankton or zooplankton => other animals (nekton and benthic) Benthic Nekton

10. Marine Ecosystems • Act as a carbon sink producing a negative feedback • An increase in amount of biomass can take more carbon out of the atmosphere

11. Unanswered Questions • Timescale of moving carbon from atmosphere to new marine ecosystems around Antarctica • Effect on total carbon cycle • Uncertainty due to other factors • Nutrient release from sea-ice • Role of Antarctica Circumpolar Current

12. Data/Methods • Use of Satellite images, preexisting charts, and averaging for the retreating of sea ice estimation 1950 Ice Front 2008 Ice Front 200m Isobath

13. Data/Methods • Used Sea WiFS (satellite) measurements to determine plankton amounts • Red = Higher concentration

14. Data/Methods • Measurements of plankton at depths deeper than satellites can view over a year Peak Season

15. Results • More area opened to phytoplankton productivity due to increase in open ocean • Around 23,900 km² of near shore area (200m or less) uncovered since 1950’s along Antarctica Peninsula • From the 1980’s18,800 km² now has phytoplankton productivity that did not before (About the size of Rhode Island, Connecticut, and Delaware or New Jersey)

16. Results Estimates of Carbon held in each type of biomass in the Ecosystem around Antarctica Peninsula (Total > 4.1 x 10⁵ tonnes) • Use other studies estimates then scale to area of lost sea ice (176 gCm⁻² and 109 gCm⁻²) • 1 tonne = 1000 kg

17. Results • Once the Carbon has entered the marine ecosystem it becomes very unlikely that it will be reintroduced into the atmosphere • Noted the benthic productivity can vary greatly, however the chances for it to happen around Antarctica are slim

18. Results • These new marine ecosystems act as a one-time carbon sink that has a limit, not as a continuing feedback • Once limit has been reached no more carbon can be added.

19. Results • Unable to determine how much carbon comes from deep ocean currents or from the atmosphere

20. Conclusions • Melting of sea ice around Antarctica Peninsula allows for the development of new marine ecosystems • These new ecosystems act as a limited carbon sink that can hold from 3.85 x 10⁵ to 2.36 x 106tonnes • What seems like a influential carbon sink is actually small • Total sink from Antarctica peninsula would only be around 11% of the carbon sink created by the expanding boreal forests (~8.4 x 106tonnes)

21. Conclusions • Some species have experienced faster growth rates due to increase of carbon in environment • Hard to predict flow of carbon and timescale of flow • Glaciers/Ice shelves around the Antarctica Peninsula occupy < 1% of the total area of glaciers/Ice shelves of Antarctica • Unpredictability of future events

22. My Opinion • Interesting predictions on new carbon sinks/negative feedback • Actually compare affect between sea albedo to carbon sink on climate • Carbon Cycle • Apply to other areas (ex: Antarctica, other near shore sea ice) • Boils down to time and money • Paying for research vessels to test • Time to study relationships

23. Qué?