Bridging the Gap: Ecology and Climate Modelling

With the prominent effects of climate change being brought to light, ecologists are under increased pressure to predict how individual species and the ecosystems they rely on will cope and change with varying effects of a changing climate1. However trying to bring two fields such as ecology and climate modelling together is no easy feat. It is safe to say that if you put an ecologist and a climate modeller in the same room they would basically be speaking two different languages. It is this gap, caused by misunderstandings between fields and a vast difference in tools used, that Dr Rebecca Harris from the University of Tasmania, wishes to bridge.

The projections that are produced by climate modellers are indeed highly essential for ecologists to study biological responses to climate change. However the understanding of these projections and the appropriateness of their use is still highly restricted due to the differences between the two fields2.

So where do the problems lie? The first and foremost thing to remember is that the projections built by climate modalists are not predictions like a weather reporter would give but rather a descriptive model of possible climate based futures derived from a given scenario. Screen Shot 2015-03-07 at 5.37.35 pmNow I know this sounds confusing however, if we look at figure 1 we begin to get an idea of how climate modelling works. What is shown is 8 different scenarios under which RF (radiative forcing) will increase over the century. It is not a prediction, but rather a variety of projections of which any could be a possible future.

Screen Shot 2015-03-07 at 5.37.09 pmNow figure 1 isn’t very helpful to ecologists as it doesn’t show climate changes overlaid on an environment. Figure 2 shows that there can be a very large difference between just 2 scenarios on a map of the earth. What does this mean for ecologists? Well they either have to come up with data for every single projection or are faced with the hard choice of determining which projections are most likely and therefore best to use.

The next issue is the downscaling of projections to a higher resolution that suits ecologists. Currently most models are too broad for ecological studies covering hundreds of kilometres . Ecologists need to see regionalised climate data, in some cases to resolutions as high as one kilometre to be able to study biological responses in certain regions3. There are a number of ways to downscale climate models, the problem with this is that downscaling can be an extremely expensive and intensive process, may not cover all climate variables such as humidity or wind and can at times require long reliable climate records2.

Another issue is that of choosing the correct Global Climate Model (GCM) to use. The IPCC uses over 50 models to create their reports, whereas the majority of ecological studies only use one. Individual models have problems with uncertainty and gaps in empirical data, thus a collaboration of multiple GCM’s is a necessity in order to minimise uncertainties and data gaps2, 4. For ecologists this means more work; they must use as many GCM’s as possible whilst insuring each is suitable for the data, independent of each other and represents the range of plausible features that are being studied.

The problems outlined above aren’t the only ones. Ecologists and modellers are faced with other choices to make such as what scenario/s to run, what variables to include, the length of the baseline period and how to present the data when using multiple projections. cs1Together these problems cause the need for increased investments in wealth and time into projects and leave a rather large gap to bridge. But what does the future hold for ecology based on climate models? Dr Harris certainly believes these gaps will slowly be bridged, I too believe the same, the more ecologists and climate modellers that start to work together the faster the bridges can be built.
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I would like to end by proposing a question for everyone: What ecosystem or species do you think climatic modelling would best benefit from, in terms of answering ecological questions related to climate change? I believe that marine climate models would be a fantastic tool for marine ecologists to help with areas of concern such as range shifts in corals or seagrasses.

1. Angert. A, LaDeau. S and Ostend. R. 2013. Climate change and species interactions: ways forward. Annals of the New York Academy of Sciences1297: 1-7.
2. Harris. R, Grose. M, Lee. G, Bindoff. N, Porfirio. L and Fox-Hughes. P. 2014. Climate projections for ecologists. WIREs Climate Change. 5: 621-637.
3. Parmesan. C, Burrows. M, Duarte. C, Poloczanska. E, Richardson. A, Schoeman. D and Singer, M. 2013. Beyond climate change attribution in conservation and ecological research. Ecology Letters16: 58-71.
4. McCreesh. N and Booth. M. 2013. Challenges in predicting the effects of climate change on Schistosoma mansoni and Schistosoma haematobium transmission potential. Trends in Parasitology. 29(11): 548-555.
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