- Apr 2024
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www.theguardian.com www.theguardian.com
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Bei einer Hitzewelle in der Antarktis lag die Temperatur 38,5° über dem Durchschnittswert. Dieser enorm hohe Wert schockiert Forschende und ist bisher nicht erklärbar. Der Guardian stellt den Kontext ausführlich dar und hat dazu mehrere Fachleute befragt. Eine neue Publikation spricht von einem regime shift beim antarktischen Sommer-Meereis. Er gefährdet u.a. den Krill und die Kolonien der Kaiserpinguine. https://www.theguardian.com/environment/2024/apr/06/simply-mind-boggling-world-record-temperature-jump-in-antarctic-raises-fears-of-catastrophe
Tags
- species: Krill
- region: Antarctica
- expert: Michael Meredith
- 2024-04-06
- institution: British Antarctic Survey
- expert: Peter Fretwell
- by: RobinMcKie
- species: emperor penguin
- process: temperature records
- Study: Observational Evidence for a Regime Shift in Summer Antarctic Sea Ice
- treaty: Antarctic Treaty
- expert: Kate Hendry
- expert: Martin Siegert
- expert: Will Hobbs
Annotators
URL
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- Sep 2016
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via3.hypothes.is via3.hypothes.is
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one can obtain good indications for theexistence of alternative attractors from field data, but theycan never be conclusive. There is always the possibilitythat discontinuities in time series or spatial patternsare due to discontinuities in some environmental factor.Alternatively, the system might simply have a thresholdresponse (Figure 2b).
While these different potential processes behind particular patterns are not all associated with alternative stable states, they are all associated with regime shifts (barring some very narrow definition of "regime shift").
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Catastrophic regime shifts inecosystems: linking theory toobservation
The title of this paper is about "regime shifts", but most of the paper focuses "alternative stable states". My impression is that "alternative stable states" and their associated attractors represent one possible cause of regime shifts, so it's interesting that that is where all of the emphasis is placed.
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A graphical model of a vegetation-water feedback
This model directly assumes a critical transition from no vegetation to full vegetation at a transition point along a precipitation gradient, so the non-linear transition of the system is built in to the model. If vegetation increased smoothly with precipitation we wouldn't expect alternative stable states or regime shifts. This isn't to say that the model isn't useful for illustrative purposes, just that it basically assumes in the notable result.
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The obvious intuitive explanation for a sudden dra-matic change in nature is the occurrence of a sudden largeexternal impact. However, theoreticians have long stressedthat this need not be the case. Even a tiny incrementalchange in conditions can trigger a large shift in somesystems if a critical threshold known as ‘catastrophicbifurcation’ is passed[11].
Distinguishing between these two possibilities will be difficult since in most cases we lack a sufficiently thorough understanding of the processes driving the system to know for sure whether an important process has undergone a sudden change.
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