24 sep. 2013

Arktiska rådet om biodiversitet

Nu när vi skriver så mycket om Arktis och nyss har skrivit om biodiversitet så passar det utmärkt att påminna om Arktiska rådets nya rapport om biologisk mångfald i Arktis. Så här sammanfattar man betydelsen av klimatförändringarna:

Key Finding 2: Climate change is by far the most serious threat to Arctic biodiversity and exacerbates all other threats. 
Summer temperatures in the Arctic during recent decades have been warmer than at any time in the past 2000 years, and the region is warming twice as fast as the rest of the planet. Within this century, temperatures in the Arctic are projected to increase by several degrees further from the 1980-2000 average. Changing combinations of high temperatures, winds and precipitation are likely to give rise to very different climates in the Arctic. Arctic summer sea ice cover – and particularly the amount of multi-year ice – is decreasing at an accelerating rate. The years since 2007 have seen less summer sea ice than any previous year in the satellite era, and 2012 set another record low. The ocean is expected to become ice free in summer within a few decades. The increased carbon dioxide concentrations in the atmosphere are also leading to acidification of ocean waters worldwide, especially in colder Arctic waters that can dissolve more carbon dioxide. Warming is also causing loss of permafrost and glaciers, affecting hydrology, vegetation, erosion patterns and other features of terrestrial ecosystems. 
The distribution of flora and fauna is shifting northwards as the Arctic continues to warm. On land, shrubs are growing taller and spreading, boreal species and ecosystems are already moving into what is now the low Arctic, and the treeline is expected to move north. While low Arctic species are expected to move into the high Arctic, some high Arctic species and ecosystems are expected to disappear or remain only as isolated fragments in high mountain areas. In the ocean, loss of sea ice is already affecting the timing and patterns of primary production, altering food webs and reducing the availability of sea ice to walrus and ice seals for resting, molting, breeding and rearing young. The total loss of some key habitats such as multi-year pack ice is expected. In the process of rapid change and transitions, new combinations of species are altering Arctic ecosystems. 
By increasing the accessibility of the Arctic to humans, climate-induced changes will facilitate increased industrial activity such as oil and gas exploration and marine shipping. These changes will in turn bring other stressors to the region. For example, ships discharging ballast water into Arctic seas may introduce invasive species that may outcompete and displace resident species. The stress of climate change does not act in isolation, but works in conjunction with other stressors, yielding even greater risks to Arctic biodiversity.

10 kommentarer:

  1. Ja hur står det till med isbjörnsbeståndet?
    Har inte hört något om dem, antar att det betyder att isbjörnarna inte minskat i antal som agw-troende förutspådde (hoppades?).
    Någon som vet något?

    SvaraRadera
    Svar
    1. Björn, du skulle kanske kolla vad som sägs i rapporten.

      Radera
    2. Tack för tipset!

      Radera
    3. Äsch, samma gamla uppskattningar som förut, inget nytt om isbjörnarna.
      Data kommer från 1992-2007.
      Konstigt att det inte finns några nya data om isbjörnarna med tanke på just isavsmältningens förmodade dramatiska påverkan på isbjörnsbeståndet.
      Jag tror att om en inventering av isbjörnsbeståndet visade att populationerna minskade så skulle polminskningen få mer uppmärksamheten.

      Radera
    4. Tyvärr tycks det som att inventeringarna inte är så omfattande och täta som björn tycks utgå ifrån. Kanske behov av mer resurser för att följa vad som händer bättre. Regher et al 2010 som tas upp i rapporten verkar vara en av de senaste analyserna:
      4. In the most supported models, polar bear survival declined with an increasing number of days per year that waters over the continental shelf were ice free. In 2001–2003, the ice-free period was relatively short (mean 101 days) and adult female survival was high (0·96–0·99, depending on reproductive state). In 2004 and 2005, the ice-free period was longer (mean 135 days) and adult female survival was low (0·73–0·79, depending on reproductive state). Breeding rates and cub litter survival also declined with increasing duration of the ice-free period. Confidence intervals on vital rate estimates were wide.

      5. The effects of sea ice loss on polar bears in the southern Beaufort Sea may apply to polar bear populations in other portions of the polar basin that have similar sea ice dynamics and have experienced similar, or more severe, sea ice declines. Our findings therefore are relevant to the extinction risk facing approximately one-third of the world’s polar bears.

      Radera
    5. En nyligen publicerad studie, McKinney et al 2013, av Grönländska isbjörnarnas diet visar hur den förändrats till mer havslevande och subarktiska sälarter.

      En annan nyligen publicerad studie, Rode et al 2013, beskriver skillnaden i effekten av minskad havsis mellan olika geografiska områden.

      Radera
  2. Tips till Björn angående isbjörnar om han nu skulle läsa detta:
    http://www.theglobeandmail.com/news/national/healthy-polar-bear-count-confounds-doomsayers/article2392523/
    /Jellba

    SvaraRadera

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