A framework to support engagement between metrology and climate science
by Prof. Nigel Fox, Dr. Emma Woolliams, Mr. Richard Barker, Dr. Paul Green, Dr. Tom Gardiner, Dr. Maurice Cox

Abstract

A measured, timely response to climate change requires trustworthy, readily assimilated information tied to action and consequences, with policy makers often desiring, unrealistically, for such data to have no uncertainty. In practice, the ‘information’ needs to derive from robust quantitative measurements typically transformed by, or providing an anchor to, models. Uncertainties in measurements and models should be described in ways that can inform decisions. The link between data and models may involve linear or non-linear processes, transition between a physical measurand and bio-geophysical parameter, various geographical scales, and ‘interpretation’. In most cases, change and trend signals are so small that it can take decades to extract the trend from a background of ‘natural-variability’ or noise. We need to detect and assess the consequences resulting from both actions, e.g., climate response to energy balance change resulting from anthropogenic greenhouse gas (GHG) emissions, and recovery due to societal action. The traditional role of metrology, assessing confidence and trust in the physical measuring systems used to obtain initial data, is achieved through calibration and traceability to SI units. However, assessing its performance and its ‘fitness-for-purpose’ to address the questions asked by a policy maker is a different matter and greatly confused by the complex chain through which the data transitions. Other than for relatively standard measurements, climate trend observations are often more demanding than can be readily delivered by metrology institutes and require research, investment and time to develop the necessary capability. Active early engagement of the metrology community is needed so it is ready to meet the calibration needs of instruments designed to address the most critical societal questions in a timely manner. Quantitative, evidenced requirements and dialogue to determine likelihood of success are needed. Metrology is not limited to the primary measurand and indeed can and should have a significant role to play in all transformational steps to the point of ‘interpretation’, where an independent assessment of confidence or uncertainty can play an important part. It is essential that the effort to reduce the uncertainty in a particular measurand is justified following any transformational process. For interactions between metrologists and the ‘climate community’ to occur efficiently requires a common interpretational framework of the ‘data to information’ transformational process, independent of societal question and associated underpinning physical measurand or data source. This paper proposes such a framework, aiding translation of societal questions into observational and traceability requirements to primary SI quantities incorporating all intermediate steps.