The same river twice: Applied climatology in a changing environment

In recent retrospectives Stan Changnon (1995 and 2005) assessed the state of applied climatology, noting its past and questioning its future, then concluding that a golden age had begun. In many respects, certain basic needs have not changed. However, the discipline operates in a context that is evolving ever more rapidly, a characteristic of many other fields. This talk explores several elements of that bigger picture. One important determinant of this context is the subject matter itself, climate, the physical system that appears to be either changing or poised for change, depending on geography, season, and other factors. A large percentage of the applications of climate knowledge concern the expected behavior and associated statistics of the atmosphere over a future period of interest. An implicit assumption, almost a core belief, that has permeated much of the field is that the statistics of the past in effect serve as a kind of prediction of the statistics of the future of interest. Enormous societal investments in the infrastructure for civilization have been made on the basis of this expectation. Now, that principle, the stationarity of climate statistics, is being called into increasing question, on the basis of recent observations, predictions, or both. At one and the same time this situation poses significant challenges and opportunities. An entire cottage industry lurks, awaiting a methodology that will pass muster. The climate change issue has immense breadth and numerous dimensions, with a crucial need for accurate but understandable interpretation to a very diverse audience. Changes of some magnitude seem inevitable, and a large number of opportunities already exist, with many more to follow. Suitable tools to assist with this complex translation will be of great value. A perpetual preoccupation and source of angst for applied climatology has been data, and the observational system that supplies these numbers. For these new uses, consistent records are a

necessity, and yet the depth and duration of the commitment to the requisite observation system is not always apparent and still widely questioned. A basic requirement is for observations that are accurate and credible. For this reason a second major preoccupation of applied climatologists has been quality control. There is much concern about mis-edits, and yet there is as yet no widely applied consistent approach or adherence to a theoretical framework designed explicitly to (for example) minimize Type I or Type II errors. Bias detection and attribution is needed to understand whether our climate records are telling us about observational processes or about climate, and are particularly important for small to modest long-term fluctuation or change. Quality control is especially difficult in mountains, with highly complex patterns exhibiting fine scale structure present at a variety of time scales, and complicated spatial correlation textures with systematic seasonal and time-scale-dependent behavior,

accentuated in some circumstances by elevation or aspect (eg, presence/absence of snow cover). Lowland populations are highly dependent on water and other natural resources supplied by high elevations, where climate histories have been greatly undersampled. These and other mountain issues are the concern of CIRMOUNT. A suite of observations, operational products, tools, and activities, that are both learning from and advising the research infrastructure, constitute the major elements of applied climatology. These

components, along with outreach and education, take place within public and private organizations. The organizational and institutional infrastructure to accomplish all this, and a process for identifying and filling gaps, are the subject of an extended ongoing dialogue about a need for, and the scope of, a more formal program for national climate services, perhaps as a National Climate Service. As a robust and inclusive multi-partner consortium, such a climate service would significantly overlap with and address the present and projected core needs of applied climatology.