Klausmeyer and Shaw 2009: Climate change, habitat loss, protected areas and the climate adaptation potential of species in Mediterranean ecosystems worldwide

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This paper presents a large assessment about the projected climate change induced chance in Mediterranean habitats worldwide. The authors look at several possible models and assess the likelihood of contractions and expansions of suitable climate in each of the study region.

After reading the paper we found that the main strengths of this study are:

  • The large number of climatic models. The authors have used all (23) of the IPPC’s GCMs to predict future climate under three (B1, A1B and A2) emission scenarios, resulting in 163 different projections. This is something one rarely sees in these types of studies.
  • The authors have also nicely produced sort of “confidence intervals” which they use to asses the likelihood of their predictions. I.e. if 90% of the models predict a site to disappear in the future etc. This can give more information to managers on how to plan their conservation strategies.

However, the study also has some weaknesses which sadly diminish the potential impact of this paper:

  • First of all, the authors decided to use an extremely conservative definition for the Mediterranean habitat, one that is also not that widely in use. Although they do compensate for this with the sensitivity analysis (using a less conservative definition).
  • The study accounts only for the changes in the (quite few) climatic factors and does not go into modelling actual species or species assemblages. Although we do acknowledge that extending the study to species habitat modelling would a) increase the already big workload significantly and b) could add certain type of uncertainties due to additional modelling phases, we do believe that simply modelling the climate can give quite a misleading picture. For example, the results of this study indicate that the overall area of Mediterranean habitat would increase in the future, mostly due to inland expansions in the Mediterranean basin and Chile/Argentina. However, as the habitat type requires climatic conditions which are produced e.g. shore areas with nearby cold ocean currents, an inland expansion might turn out to be impossible for some of the species. These types of factors can not be included into the results when modelling only the climate and not the biological linkages.
  • The actual assessment of the biome’s protection level remain fairly weak in this study. First of all, the conversion of polygon PA-data into the grid cells is done in a very coarse way, leaving some uncertainties about the true location and amount of protected area. There are many more sophisticated approaches to this issue, but for some reason the authors have decided not to use them. Secondly, the way the authors have calculated the changes in protection level remains a bit obscure: Did they only look at the confident contractions/expansions or also the likely contractions/expansions? Overall the question of expansions to new protected areas and the climate adaptation potential is very lightly discussed and no comprehensive analysis about this matter seems be done.

Overall the paper presents a nice global assessment, that brings together all the 5 regions of Mediterranean habitat and provides one good way to tackle the inseparable problem of uncertainty in climate change projections. However, the actual questions proposed by the title of this paper still remain unanswered: simply modelling the shifts in a set of climatic factors is not enough to give reliable information about the changes in the actual biome. Also the authors seem to be emphasizing those areas where the current climate will remain stable, giving, in the end, very little to assess about the actual changes in habitat loss, protection level and climatic adaptation potential of species.

Final conclusion: Nice paper to read, but the novelty and practical impact of the study remains weak.

Link to the paper
Klausmeyer and Shaw 2009. Climate change, habitat loss, protected areas and the climate adaptation potential of species in Mediterranean ecosystems worldwide. PLoS ONE. Vol. 4(7), p.6392-6401

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006392