With record global temperatures, giant storms, extended tree-killing droughts, and all the other assorted disasters we are experiencing, our fears that we humans are messing up the planet are becoming true. For CNPS, we see a lot of potential threats to the flora, as if the dead oaks and Sierra Nevada pines weren’t evidence enough.
My talk will examine the methods by which we try to predict probable local conditions under differing scenarios of carbon dioxide and methane additions and controls. Taking a ‘best guess’ on this we have to apply it to a chosen Global Climatic Model, of which there are over 20. We test each model to see how well it would have predicted climate that we have already experienced, and we usually get a couple of models that seem to fit. So far we see great agreement on rising
temperature, but considerable variation in predicting rainfall. We then take an average of all of the chosen models, and hope that this is going to be accurate.
Once the model is in place, we look at the flora. Each species has a range of tolerable temperatures and rainfall history in which it will survive, albeit with fluctuations in numbers. If the climate models show conditions that exceed species tolerance, then we can expect extirpation. For example, expected future conditions in Joshua Tree National Park actually result in elimination of most of the Joshua trees, but new habitat opens up in Nevada as the cold high desert warms up.
From the ecological point of view there are the added issues about such things as whether an insect vital for pollination is able to shift in tandem with a plant, the added invasion potential of alien weeds, and other issues. It is possible to build a threats-risk analysis for each species, and such things as vulnerability indices are constructed.
Now we have some potential triage issues. Should CNPS do “assisted migration” where we will move a plant into more suitable habitat while hopping across terrain that the plant would not be able to cross on its own? Do we spend our resources on the rarest species at risk, or on the fate of more common plants like oaks? In some ways we will play Noah at the door of the ark… or not. I hope to make my presentation interesting and promise to find as many optimistic points as possible. I know I have seen some… honest…
- – David Chipping