Re: [maxent] How to choose "appropriate" GCM

[swammy50]

The GCM's are different models of the global climate system. There is no right model. Some models seem to do better at reproducing features of historic climate in certain regions. However, representing the past accurately is no guarantee of projecting the future accurately, particularly since we are headed into a novel global climate state.

The RCPs are different emissions scenarios, the lower the number the lower the greenhouse gas emissions assumed. Again there is no right answer I which to choose except the answer may depend on the question you are addressing. Remember, none of these models is predicting the future, they are all wrong in that context. But by using them in a Maxent model we can learn how species might respond to different climate futures.

I caution against ensemble means of models within scenarios (means across scenarios make little sense). The scenarios were designed to test global climate response to GHG emissions while Maxent models are designed to test response to climate, not the same thing. So a mean within scenarios is no more accurate than any one  model alone. Also note that ensemble means of climate end up in a region of climate space that no individual model occupies.

My recommendation for managers is to pick models that represent extremes (high and low precip for example) and use those to test the sensitivity of species response. But the best recommendation will depend on your question.

Hope that helps

Sam

On Sep 29, 2015, at 9:47 PM, Wena Japitana <weeja...@gmail.com> wrote:

Hi!

I'm planning to use MaxEnt to model the habitat suitability of a plant invasive species. I intend to use the IPCC 5 predictions for 2050 and 2070, my problem is that I'm not sure which GCMs and emission scenarios I should be using coz there seems to be too many. I also have some confusions about the four RCPs, RCP2.6, RCP4.5, RCP6, and RCP8.5 and how they work. I hope you could help me with this one.

Wena Japitana

MSc Student

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