a look at the arctic over the past 100 years

  1. 5,732 Posts.
    A post in another thread unrelated to the arctic alerted me to this study, discussing changes in the arctic over this past century, particularly in the Barents Sea area: Bengtsson 2004. I posted most of this in the other thread and figure what I found shouldn't go to waste so am putting it up as a new post under the proper topic heading for anyone who's interested in the arctic itself. Here are some relevant highlight snippets from the Bengtsson paper (italics are bits I added for clarity):

    An evaluation of the coupled model suggests that a major part of the warming (ie earlier 20th century) is caused by transport of warm ocean water, in the uppermost 125 m of the ocean model, into the Barents Sea, driven by stronger-than normal surface winds...We suggest that the warm Arctic event might have occurred through an aggregation of several consecutive winters with a pronounced high-latitude westerly in the Atlantic sector....Needless to say, a necessary condition for the Arctic warming event to commence depends on changes in the large-scale atmospheric circulation. A comprehensive discussion of this is outside the scope of this study. As discussed in the introduction, there are many possibilities. Our view is that natural processes in the climate system are the most likely cause; at least, there is hardly any information from observations or from model experiments to the opposite....Observational data in the Arctic from the first part of the twentieth century are relatively sparse, especially from the Arctic Ocean. The gridded datasets of surface temperature and sea ice are essentially constructed from a limited number of observations, although the autocorrelation structure used in the analyses are calculated from present data. However, observations from the most sensitive region, Barents Sea, are fairly good and better that previously thought, which means that we can have reasonable confidence in the result....What consequences may the findings of this study have for understanding the possible evolution of the Arctic climate? Notwithstanding an expected overall climate warming it is suggested that the Arctic climate would be exposed to considerable internal variations over several years initiated by stochastic variations of the high-latitude atmospheric circulation and subsequently enhanced and maintained by sea ice feedback.
    The Barents Sea region is identified as a particularly sensitive area in this respect. Realistic simulation of the Arctic climate consequently requires an accurate representation of atmosphere - ocean - sea ice feedback processes.


    Here is a pdf presentation by Ola M. Johannessen who was lead author on another paper with Bengtsson in 2004. It includes some of Bengtsson's work and compares the current warming with fluctuations in the arctic in the first half of last century. This presentation is short, fairly easy to read and has lots of charts and figures. Good for a quick overview (bear in mind it was prepared in 2004 and does not include events such as the large ice loss in 2007 etc or recent winter cold spells in parts of the arctic).

    A major research effort was conducted in the early 2000s, called the Arctic Climate Impact Assessment. It involved 300 researchers and three years of work. The reports can be found here. I haven't read them yet so cannot comment on their contents. If anyone has an interest in the arctic I'd love to see your comments on it.

    Finally, here are some articles relating to the arctic now and in recent history:
    Realclimate 'Cold Winter in a World of Warming'
    Realclimate article on satellites and how they are used
    Realclimate on how (disproportionately) excited some people get about ice and no ice
    An article by Tamino on declining arctic ice from a statistical perspective, with links to longer term studies.
 
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