Essay

Environmental Perspectives 12/2019

Environmental Monitoring – complex but indispensable

Anyone wanting to evaluate the condition of the environment, to understand how it has changed in the past and why, to use computer models to forecast how it will develop in the future subject to changes in climate and land use, must also monitor the environment and collect data. We already have copious amounts of data, with more coming in rapidly thanks to new satellite missions, a globally networked infrastructure (Internet of Things) and the broadening of citizen science. But when the questions become more specific and we want to analyse complex environmental systems in greater detail, we often discover that the data are still insufficient to provide us with plausible answers. This may be because data are missing, such as from remote and inaccessible regions, or because the data required in the specific case are not what was measured. For example, remote sensing methods can be used to observe ecosystems over a large area. But when analysing and evaluating processes in ecosystems, the conclusiveness of the resulting data can be limited and the uncertainties in interpretation can be large. Then additional measurements are required directly in the systems – in the soil, on trees, in rivers or in cities.

But when the questions become more specific and we want to analyse complex environmental systems in greater detail, we often discover that the data are still insufficient.

A comparison with medical diagnosis can help to illustrate the challenges and complexity of environmental monitoring. In medicine, the focus is on a human being. In environmental monitoring, the focus is on the environmental compartments of the soil, air or water and their interactions. And, as in medicine, so also in the environment, investigations on the healthy object contribute significantly to the fundamental understanding of how different functions and processes are interrelated – and will ultimately help us to prevent or even cure diseases.

Of course there are significant differences between medical diagnosis and environmental monitoring in the size and accessibility of the object. However, the investigation concepts and methods are quite similar. Visual inspection of the patient can be compared with remote sensing in the environment. If this external assessment is not sufficient, various physical methods can be used to get more insights. If these non-invasive methods are still not enough to clarify everything, invasive methods must be used to take and analyse samples.

In a direct comparison, medical diagnosis has the advantage that the general structure of the object of the investigation (the human body), its organs and their functions are at least basically the same and are very well known. In addition, findings can often be interpreted very well based on thousands of studies that have already been conducted. In contrast, it is significantly more difficult to transfer methodological procedures and interpretation approaches from one ecosystem to another.

Designing environmental observations is comparatively easy if their goal is clearly defined and suitable models exist that describe the states and functions of the systems under investigation. For example, sensitivity analyses can be used to determine to which changes the system reacts especially sensitively. This is an important information in determining where observations should be focused and what resolutions in space and time are required. Whether the investigation concept is technically feasible must then be evaluated based on the state of the art and a cost/benefit analysis. If there is a discrepancy between the concept and practical feasibility, this can also serve as the impetus for new technical developments.

It is more difficult to identify or quantify interrelationships and processes that are still poorly understood. Thus, driven by the limitation of material and human resources, there has been an intensive scientific discourse for years regarding which observation parameters are the right ones and which time periods the observations should cover. It must be taken into account that environmental systems often react to changing environmental conditions with a strong time lag, which would indicate a need for long-term monitoring in many cases.

One of the best-known examples of the importance of long-term environmental monitoring is the measurement of the CO2 content of the atmosphere on the Mauna Loa volcano on Hawaii, which was started by Charles David Keeling in 1958. At the time, no one could have imagined the importance this measurement would one day have. But in the mid-1970s, the data collected over years yielded the first metrological indication that humans were influencing the global climate. Keeling and his successors have continued these measurements up to the present. The resulting data series of the atmospheric CO2 content and its graphical representation – the Keeling curve – is without doubt one of the most well-known graphs in modern scientific history, even outside the halls of natural science. Continuous and long-term measurement programmes are therefore indispensable for distinguishing between unusual individual effects and significant trends, in order to more reliably forecast developments in ecosystems and for checking options for adaptation or prevention. UFZ has therefore been running its own research infrastructures (TERENO, GCEF) for long-term environmental research for many years and is also involved in various international research networks (ICOS, LTER) with these.

However, environmental research is faced with completely different challenges when the task at hand is to predict the long-term effects of short-term extreme events such as heat waves, droughts or floods, for which both the time and place of occurrence can rarely be predicted in the long term. The metrological investigation of such events requires significantly greater flexibility than can be provided by permanently installed and continuously operated measurement systems as in long-term environmental monitoring. A flexible, modular and mobile infrastructure that is suitable for this purpose is to be developed under the auspices of the Helmholtz Association by 2022. More information on his ambitious project, which goes by the name of MOSES (Modular Observation Solutions for Earth Systems), is given in the following feature article.

To cover story Umweltperspektiven 12/2019:
Environmental Monitoring – complex but indispensable (in Gernan)