Arctic climate change and effects on the ecosystems

Transcription

1 Arctic climate change and effects on the ecosystems NalânKoç Centre for Ice, Climate and Ecosystems (ICE) Norwegian Polar Institute

2 The Arctic Pacific Ocean Main inflow Main outflow Main river inputs Arctic Ocean Atlantic Ocean AMAP (1998)

3 Arctic regions experience amplified climatic change 1.6 to 2.1 C temperatures compared with the mean. The Arctic is warming at almost twice the rate of the rest of the world. - Positive feedbacks

4 Arctic summer sea ice is disappearing.. (NSIDC)

5 Change in the age oficeonthe Arctic Ocean Sources: NOAA report State ofthe Arctic, october2006,&nsidc.

6 Source: National Snow and Ice Data Center, University of Colorado at Boulder, USA. Updated from Stroeve et al

7 The ice associated ecosystem

8 Reduced ice extent and thickness/age of the ice Ice fauna -Gammarus wilkitzkii B. Gulliksen Living habitat Ring seal K. Kovacks Pupping, moulting and resting platform Polar cod (B.saida) Polar bear B. Gulliksen J.E. Søreide Refugee and feeding ground Feeding/hunting ground

9 Sea ice plays a dual role in polar seas: both providing a habitat for ice algae and regulating the available light for primary production Polar regions: two sources of primary production Sea ice algae Phytoplankton (time difference!) Decrease in sea ice: Changed timing Phytoplankton Sea ice algae

10 Potential future scenarios Less sea ice = more light increased primary production BUT higher primary production = higher secondary production?

11 SEA ICE Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. Open water Sea Ice Icealgae phytoplankton Match eggs females nauplii Population Biomass Søreide et al GCB

12 Earlier ice break up limited ice algae April May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March Open water Sea Ice phytoplankton Mismatch? eggs females nauplii Population Biomass Søreide et al GCB

13 BIOMASS 32 g C. finmarchicus 28 g ( g DW m-2) C. glacialis 0.5 g ( g DW m-2) C. hyperboreus ( g DW m-2) 10 g Søreide et al DSR II

14 Reduced sea ice conditions, earlier break-up Seals follow the ice Ringed seals Bearded seals

15 Ringed seal movements

16 Reduced sea ice conditions, earlier break-up Polar bears follow seals

17 Ivory gulls follow polar bears and drift ice

18 Expected changes in Arctic sea ice are certain to cause alterations to the forage-base of virtually all top trophic Arctic animals in marine environments, including density and distributional shifts in their prey species, as well as potential losses of some of their traditionally favoured fat-rich, Arctic fish and zooplankton. Even though overall production levels are likely to be higher in an Arctic with a shorter ice-covered season, resources are likely to be much less predictable in both a time and space than the situation experienced in recent millennia when multi-year ice (MYI) has always been a significant feature of the Arctic and a reservoir for microbes, algae, invertebrate fauna and even larval fish to seed first-year ice, and where retraction and expansion of ice edges have largely taken place over shallow shelf seas, causing upwelling and a distinctive productivity pulse that has been regionally restricted. ice-associated animals are likely to face increased competition from invasive temperate species, increased predation from species formerly unable to access them in areas of extensive sea ice or simply because the water temperature was restrictive, increased disease risk and possibly also increased risks from contaminants. Over the coming decades it is also likely that top trophic Arctic animals will face increased impacts from human traffic and development in previously inaccessible ice-covered areas.

19 How will the future look like?

20 ICE-Ecosystems Understand the effect of changed ice structure, proximity to land and bathymetry on the ice-associated ecosystem. 12 Aug. 2010

21 ICE-Ecosystems Key elements: Influx of warm Atlantic water Bathymetry Marginal ice zone Over the shelf? Distance from land Ice & snow characteristics Sunlight patterns Winter time 4 months without sun Summer Midnight sun 4 months with continuous daylight.

22 To developfuture scenarios for Arctic marine ecosystems under decreasedice cover, it is important to: Consider timing ofbiologicalkeyprocesses Life strategies/ speciesadaptations Understand couplingamongtrophiclevels Carbonflow: sympagic-pelagic-benthic Includefoodquality as an importantmeasure

23 Thank you!