As every year we humans pump out more and more carbon dioxide, our climate is changing. While select few in their fields disagree that any alterations are human-induced, the majority of the scientific community accepts the data which shows global warming and other changes - ocean acidification, for example - are occurring, and it's our fault. Even still, we hotly debate exactly what needs to be done, and meanwhile, the ecosystems are shifting.
While we argue who should cut what emissions or who's to blame, species are going extinct, and others are moving. Exactly how much is changing is surprising. Just ask Diana Stralberg - her team just published a fascinating paper in PLoS ONE about bird communities in California. They found that 60 years from now, over half of California could be occupied by novel assemblages of bird species. This means species will be competing with species they have never seen for food, nesting space, and survival.
The research team wanted to know how global warming and predicted temperature changes might affect the bird communities in California. Birds are often limited to specific temperature ranges. Stralberg and her colleagues hypothesized that as the overall climate changes, so, too, will the distribution patterns of bird species. So, they used a multivariate modeling approach to quantify the potential change in breeding bird communities based on current and future distribution models for 60 focal Californian species.
What they found was nothing short of staggering. Depending on the variables used - community scales, algorithms, and climate models - the areas that would be host to completely mixed-up species groupings ranged from 10% to 57%. They found that many of these new assemblages - up to 50% - would be completely unlike any current bird communities. The image above shows how different California's bird communities will be according to the different models. The redder the color, the fewer current bird communities exist that are similar, or analogs, to the community predicted to occur there in 60 years. In other words, the redder an area is, the less comparable it will be to anything we've ever seen. This means that we have, at best, a weak notion of what would happen to the different species involved and how they would interact with their environment. This could lead to dramatic community reshuffling and unpredictable patterns of species interactions.
What is out of scope of the model is how these new interactions might affect the populations and distributions of species. For example, the model might place two species with similar food niches in the same area, but it doesn't reveal how that competition might affect the population density of either species. One might out-compete the other causing local extinction, or both might survive in high numbers - we don't know, especially for areas with no current analogs to compare to. With these new interactions will inevitably come new challenges for conservation and species management, particularly for endangered species.
Models like this one show just how much climate change is impacting our planet. Not in 100 or 1000 years - now, in our lifetimes. It's likely that my generation and up and coming scientists like myself will see an unprecedented dramatic shift in the ecology of the world we live in, and it will be our responsibility to deal with whatever is left.
And yet, old men in starched suits who likely won't last to see the impacts of their actions are the ones who are debating and deciding should be done. Sometimes is just makes me angry to think about how unbelievably unjust and unfair it all seems, but most of the time, it just makes me more determined to do what I do. I'd like to think that, someday, I might be one of the old, grouchy people deciding what my outdated generation will leave as a legacy to the ones that follow, and if so, I'd like to believe that my decisions will be better.
Stralberg, D., Jongsomjit, D., Howell, C., Snyder, M., Alexander, J., Wiens, J., & Root, T. (2009). Re-Shuffling of Species with Climate Disruption: A No-Analog Future for California Birds? PLoS ONE, 4 (9) DOI: 10.1371/journal.pone.0006825