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Global Climate Change on a Regional Level

An Interview with Professor Harry Vereecken

How is climate change affecting Germany? What ecological and economic conse-quences does it have in the different regions – from the North German Plain to the Alps? Finding the answers to these questions is the aim behind the project entitled Terrestrial Environmental Observatories (TERENO). Prof. Dr. Harry Vereecken, Director of the Institute of Bio- and Geosciences at Jülich, coordinates the network of six Helmholtz centres together with his Jülich colleague Dr. Heye Bogena.

Question: There are a plethora of climate monitoring stations – what’s so special about TERENO?

Vereecken: What is unique is that we are intensively monitoring all components of the terrestrial system – soil, groundwater, plants, and atmosphere – in four regions of Germany. This is the first time that such a large and diverse landscape is the subject of a long-term and interdisciplinary investigation. The observation area for which Jülich is responsible, namely the Rur observatory, stretches from the Eifel National Forest to the Lower Rhine Embayment and is as big as Luxembourg.
We will collect data here for a period of at least 15 years – on the greenhouse gas carbon dioxide (CO2) and the climate, as well on the nitrogen budget, methane formation, water and soil quality and on biodiversity. At the same time, we will analyse the land use. What are the consequences of reforestation or open-cast mining? Will farmers have to water more in the future? Up to now, there have not been enough data available to answer this question.

What knowledge gaps are particularly serious?

Vereecken: We know very little about processes in the deeper soil layers. And yet they play an extremely important role in terms of the climate. This is where a large proportion of bound carbon is stored – globally estimated to be around 1,600 billion tonnes. It is therefore essential that we find out how fast it is converted and released back into the atmosphere as CO2, and how temperature increases or changes in the water budget affect this process.

How do you acquire such information?

Vereecken: We employ a variety of different methods – from remote sensing using satellites and radar stations to sondes in the soil and lysimeters. Lysimeters are extracted soil cores measuring around 1.5 cubic metres in metal containers that are open at the bottom and allow us to precisely measure the transport of water and substances. Within the framework of SoilCan, a TERENO subproject, a total of 120 lysimeters are being installed in the four observatories. All measured data are transmitted via wireless networks and monitored in real time.

Basically, we’re talking about blocks of soil in large tin cans – what can you discover with them?

Vereecken: Among other things, lysimeters can be transported to other sites both within and between the observatories – for example, from regions with a lot of rain to regions with low precipitation or from cooler to warmer regions. This allows us to observe what happens, for example, when grassland soils or arable soils in the Rur observatory are subjected to greater drought, as is common in East Germany. In this way, we can simulate future climate changes.

Why do the measurements take so long?

Vereecken: 15 years is actually a short period of time for such studies. It takes hundreds of years to break down stable carbon compounds in the soil. Although we don’t want to study weather fluctuations of individual years, we do want to study the development and impact of climate trends in the long term. This is why it’s important that TERENO is connected to other long-term research projects, for example the EU Network of Hydrological Observatories (NOHA), which aims to record the water budget in a large number of European regions. Our work in the Rur observatory is also directly connected to the "Transregio32" (TR-32) Special Research Centre in which Forschungszentrum Jülich is cooperating with the universities at Cologne, Bonn and Aachen. TR-32 uses the same infrastructure that is made available by the Helmholtz Association.

Can you use all of this to look into the future?

Vereecken: If we combine satellite data, detailed measurements on precipitation and soil moisture with information on the groundwater level, for example, we will be able to predict more accurately than today whether there is a danger of flooding.
We will use the coupled measurement data to further develop models that will allow us to make better regional predictions on climate change and the ecological and economic consequences that we can expect.