The Need for a Systems Approach to Climate Observations

There is compelling evidence that the climate is changing, for whatever reason. We discuss the degree, nature, and cause of the climate variations and whether there is in fact a change, but the only way to resolve the issue is with solid information. This requires improved global observations of the state variables and the variables causing change (the forcings), the means to process these and understand them, and the ability to set them in a coherent physical (as well as chemical and biological) framework with models for diagnostic and prognostic purposes. Meanwhile, the information that helps settle these arguments and reduces uncertainties is also extremely valuable for many other purposes, including a myriad of practical applications for business, industry, government, and the general public. The following is a list of strategic requirements necessary for a comprehensive climate observing system: Climate observations from both space-based and in situ platforms are taken in ways that address climate needs and adhere to the 10 principles outlined by the NRC. The international framework for sharing data is vital. A global telecommunications and satellite ground systems network and satellite data telemetry capacity to enable data and products from all observing platforms to be disseminated. A climate observations analysis and tracking capability that produces global and regional analyses of various products for the atmosphere, oceans, land surface and hydrology, and the cryosphere. Four-dimensional data assimilation and reanalysis capabilities that process the multivariate data in a physically consistent framework to enable production of the analyses, not just for the atmosphere, but also for the oceans, land surface, and cryosphere. Global climate models that encompass all parts of the climate system and that are utilized in data assimilation and in making ensemble predictions originating from the initial observed state. A climate observation oversight and observing system monitoring capability that tracks the performance of the observations, the gathering of the data, and the processing systems. This must also include the resources and influence to fix problems and the capability to communicate climate requirements when observational systems are being discussed and established, such as for weather purposes or in establishing requirements for instruments on satellites. Although much has been learned about climate from past and present observing systems, we do not have an adequate climate observing system at present. Instead, we make do with an eclectic mix of observations mostly taken for other purposes. Nor are they adequately synthesized. Hence, in addition to making new observations, there is a strong rationale for building the system, and incorporating the management principles described here.