…is the title of an open access paper just published in Nature by a group of researchers at the University of Hawaii that attempts to estimate when future climates will move beyond recent ranges, and what effects that will have on biodiversity of several major taxa. I have some thoughts on this paper, especially on its overall approach. I rarely care about specific results presented in any paper until I’ve been able to look closely at its conceptual approach, assumptions (often unstated), and specific methods; what is the point in knowing what some paper claims to have found, without knowing pretty exactly how they went about it (and why)? In that regard, this paper could readily be used as a springboard to discuss a number of highly important issues in scientific practice generally, and in earth system science and/or ecology specifically.
The need to examine papers this way (i.e., as if one were a reviewer) raises a very important issue by itself, that is, how can anybody possibly read even a small subset of existing papers in a field? The answer is, that unless you’re a genius with a very wide scope of knowledge and training, and are a very focused and fast reader, or greatly restrict your scope, you can’t. Personally, I know very few people who qualify as such, zero in fact. You can skim things, you can read abstracts and discussion/conclusions, look at the graphs and tables, so as to get the general gist of the arguments and conclusions, but rarely can you delve into deep methodological details, except at the expense of the breadth of papers read. Detailed examination takes time, serious time, and a sound understanding of the fundamentals of the subject matter itself, and also of statistics and numerical analysis more generally, and the ability to judge the validity of the application(s) thereof to the subject matter.
This stuff is complicated; it’s not simple, it’s not easy, it’s not quick, it’s not automatic. It’s not molecular genetics, where important theoretical bases (e.g. inheritance rules, gene expression processes) are tight and well understood, and laboratory and analytical methods are frequently standardized and well defined. It’s environmental science; the variability is large, the contingencies many, the analytical methods all over the map and often poorly evaluated before being extensively applied. It wouldn’t be quite so bad if the focus was always maintained on certain environmental science sub-disciplines, but it’s not. Instead, inherently uncertain predictions in say, climate science, are often used as the basis to predict changes in climate-dependent variables, which themselves are highly complex, potentially poorly defined/quantified, and affected by many possible drivers.
Scientific publication is now like a fire hose stream of information coming at you, as is quickly realized by perusing publication databases like the Web of Science for a couple of hours–there are far more publications coming out daily than anybody can keep up with, for a topic as broad as the earth and environmental sciences (and same for other large topics). You want information of a quantity and quality you can handle, and instead it comes at you with the mass and velocity of water from a fire hydrant, whereupon you realize that you need a well considered strategy as to how you’re going to make any progress. In short, there’s an enormous gap between the volume of research coming out daily, and the number of people evaluating it in depth, and this is without question a recipe for problems of various kinds, seen on an ongoing basis.
This situation leaves you, the curious, with a few options. One is to take published science at face value, trusting the publication process to get things right a high percentage of the time, going largely with the flow, i.e., the consensus. A second is to make decisions about which scientists and/or research groups you trust and restrict yourself to reading their papers. A third is to make your own judgements, but focusing on only those papers either appearing to be the most important, however judged (the filtering process itself still a significant time requirement itself), or on those you can actually understand well. A fourth is to throw up your hands and walk away from the whole thing as something you really can’t deal with effectively.
OK, on to the paper. To get right to it, I think there are several serious problems with the work, largely conceptual, involving the general approach(es) taken. The paper’s stated main goals are to: (1) provide evidence of when future climates will move outside the range of historical climates, and (2) estimate where, and how large, the effects of those changes will be on biodiversity, generally, a grand objective indeed. The general approach used goes thus: (1) use GCMs to estimate the ranges of variability from 1860 to 2005 for several important climate variables centered around region-specific energy and water budgets, (2) use those same models to estimate when the mean state of those variables will exceed the high ends of those ranges, given two hypothetical GHG atmospheric growth rates, and (3) make some inferences about what these dates, along with nation-level economic conditions, imply for future “biodiversity” dynamics/stability.
The paper starts with the now seemingly obligatory litany of what future climate change might or could do to society and ecosystems. This kind of stuff gets repeated over and over in papers, usually with qualifying “coulds”, “mays”, or “cans” in the phrasing. I pay no attention to such text except to (sometimes) look at the citation list for any surprises, because it’s almost never useful information. We don’t need to be told that species can either adapt, migrate or “go extinct” in response to environmental change–this is not a chapter in a high school biology text. Nor do we need references to possible mental illness effects, or potential changes in “geopolitical stability”; if the stated goal is to discuss climate change rates and resulting effects on biodiversity, then please, stick right to it. The earth could also get blasted by an intense solar wind tomorrow, Haiti or San Francisco could get destroyed again by an earthquake, but I don’t see those things mentioned. Given how little space one has to make complex arguments in the science glamor journals (Nature, Science, PNAS, etc.), due to word limits, you’d think such irrelevancies would get axed in short order. Alas, to the contrary, you see them over and over again. They seem to have no purpose except to create or reinforce a particular attitude of mind, the effect of which does nothing but make me suspicious (although not necessarily prejudiced). I’m not interested in sweeping generalizations, especially when they don’t relate specifically to the stated goal(s).
The last sentence of the introduction ends “our understanding of climate change still lacks a precise indication of the time at which the climate of a given location will shift wholly outside the range of historical precedents”. The paper then proposes to provide such precise dates, and relate them to biodiversity dynamics. OK; you set the bar at the height you propose you can clear…now lets’s see you clear it.
Note: edited for clarity.