Extinction artifact in coarse scales

CO2 Science reviews a study showing that the appearance of high levels of extinction due to shifts in climate is due to the coarse resolution of the grid cells used in the simulations. This is another vindication of the conclusion of our 18 author collaboration.

When grid cells are coarse, a one degree shift in temperature, say, affects a large area, and can appear to eliminate all habitat for a species in the grid cell. The virtual species must move a long way to find another suitable grid cell. In actuality each coarse grid cell contains a range of temperatures. When the grid cells are finer, there will most likely be areas within the grid cell with suitable habitat for the species, enabling it to persist through large climate variations.

Refugia are well known to have a crucial role in species’ persistence, and may be characterized as areas of high spatial heterogeneity. It is easy to see that choice of scale would have a large effect on determinations of species persistence, and great caution would be needed in interpreting results of simulations conducted on coarse grids.

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0 thoughts on “Extinction artifact in coarse scales

  1. The issue of microclimates is not trivial in this respect. In Michaels et al’s review of the recent CCSP report:
    “Models of extinction of species that “evolved based upon historical climate” completely neglect the fact that microclimatic refugia are likely to preserve many species, despite their larger “historical climate”. I offer the CCSP the stand of Abies balsamea growing in northeast Iowa, far away from the “historical climate” of the boreal forest. According to every climate/extinction model, it should not be there.”

    Indeed, Balsam Fir has no business being that far south. And yet it is…

    • Excellent point Andrew. Just because we have determined the ideal climate for a species does NOT mean that it cannot survive outside of that narrow limitation!!

      • Actually, that’s a separate, bit also important point. What I was saying was that, the environment is different in small areas that are not defined by broad latitudinal swaths. Small areas of NE Iowa have climate more similar to states to the North.

      • I’m not even sure what is meant by an optimal environment for a species/genus/whatever. It is likely that a species does best in a place where both the available benefits are maximised AND the threats are minimised. These can be mutually exclusive. e.g. a place of abundant food can also be a place of abundant predators. Are you aware of work showing that many communities live “on the fringe” of where they would like to be and are therefore resilient to location change? (I do not kow the answer. I’m merely using a bit of observation and logic, no formal studies I can quote).There are numerous examples of creatures using much energy to gather food that is incrementally just able to support species existence, e.g. birds that fly huge distances to breed and feed, penguins that swim miles each day, wharfies spending a lot of effort to avoid work, etc.

      • I’m not a follower of the Ecological literature, but it wouldn’t surprise me if a lot of species tend to live at the margins of their “ideal” habitat. There are any number of reasons why this makes sense, I think one is that they maximize their distance from competitors by not living where they would all be gathered together, but along a perimeter. But it also would mean that when dealing with changing conditions in their environment, they would very quickly become aware and be able to move with the changes, not suddenly finding themselves trapped in the center of a dwindling habitat. A sort of “advance warning” of environmental shifts.

    • Yes, indeed!

      And oceanic cyanobacteria have no business transferring a small portion of their photosynthetic electrons to their external environment (while they are fixing 20 – 30% of the atmospheric CO2) – but we now know they do:

      http://www.newswise.com/articles/view/565664/?sc=dwhn

      That electron has to go somewhere and e.g. some of it goes into the aerobic reduction (!) of methylphosphonate to methane in phosphate-stressed surface waters.

      http://www.biogeosciences.net/7/1099/2010/bg-7-1099-2010.pdf

      The key point is that our detailed ecological knowledge of why certain adaptations are in place is still so very limited yet our hubris about our so-called ‘understanding’ of ecosystems, their subtleties, their refugia etc is so huge.

  2. The issue of microclimates is not trivial in this respect. In Michaels et al's review of the recent CCSP report:”Models of extinction of species that “evolved based upon historical climate” completely neglect the fact that microclimatic refugia are likely to preserve many species, despite their larger “historical climate”. I offer the CCSP the stand of Abies balsamea growing in northeast Iowa, far away from the “historical climate” of the boreal forest. According to every climate/extinction model, it should not be there.”Indeed, Balsam Fir has no business being that far south. And yet it is…

  3. Excellent point Andrew. Just because we have determined the ideal climate for a species does NOT mean that it cannot survive outside of that narrow limitation!!

  4. Actually, that's a separate, bit also important point. What I was saying was that, the environment is different in small areas that are not defined by broad latitudinal swaths. Small areas of NE Iowa have climate more similar to states to the North.

  5. Yes, indeed!And oceanic cyanobacteria have no business transferring a small portion of their photosynthetic electrons to their external environment (while they are fixing 20 – 30% of the atmospheric CO2) – but we now know they do:http://www.newswise.com/articles/view/565664/?s…That electron has to go somewhere and e.g. some of it goes into the aerobic reduction (!) of methylphosphonate to methane in phosphate-stressed surface waters.http://www.biogeosciences.net/7/1099/2010/bg-7-1099-20...The key point is that our detailed ecological knowledge of why certain adaptations are in place is still so very limited yet our hubris about our so-called 'understanding' of ecosystems, their subtleties, their refugia etc is so huge.

  6. I'm not even sure what is meant by an optimal environment for a species/genus/whatever. It is likely that a species does best in a place where both the available benefits are maximised AND the threats are minimised. These can be mutually exclusive. e.g. a place of abundant food can also be a place of abundant predators. Are you aware of work showing that many communities live “on the fringe” of where they would like to be and are therefore resilient to location change? (I do not kow the answer. I'm merely using a bit of observation and logic, no formal studies I can quote).There are numerous examples of creatures using much energy to gather food that is incrementally just able to support species existence, e.g. birds that fly huge distances to breed and feed, penguins that swim miles each day, wharfies spending a lot of effort to avoid work, etc.

  7. I'm not a follower of the Ecological literature, but it wouldn't surprise me if a lot of species tend to live at the margins of their “ideal” habitat. There are any number of reasons why this makes sense, I think one is that they maximize their distance from competitors by not living where they would all be gathered together, but along a perimeter. But it also would mean that when dealing with changing conditions in their environment, they would very quickly become aware and be able to move with the changes, not suddenly finding themselves trapped in the center of a dwindling habitat. A sort of “advance warning” of environmental shifts.

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