The superconducting gravimeter on the Zugspitze measures the temporal variations in gravitational acceleration continuously and with high precision. In a research project called G-MONARCH, gravimetric methods are being used to improve our understanding of the Alpine water balance using the Zugspitze as an example. G-MONARCH stands for "Gravity-MONitoring for Alpine Research Catchment Hydrology". By analyzing gravity, it is possible to make statements about the underlying masses and their changes.

The building on the Zugspitze, where our gravimeter is located, is the former high-altitude radiation measuring station of the Max Planck Institute for Extraterrestrial Physics and is a listed building. Built in 1963, the futuristic building is also known as the "tooth" or "submarine".

The picture shows the satellite receiving station in Ny-Ålesund on Spitsbergen. The two domes are two antennas. The hut in the middle houses the receiving equipment. The station receives data from research satellites in polar orbits. Ny-Ålesund is the northernmost place in the world that can be reached by regular means of transportation such as airplanes and ships.

The current most important task of the NYA station is the reception of the two GRACE Follow On satellites (in orbit since 2018). The GFZ is responsible for the complete reception of the satellite data, for which the NYA Station is used as the primary receiving station of the mission.

Coral microatolls are excellent indicators of relative sea level and provide information about past sea level changes. Coral colonies grow and survive near the base of the intertidal zone. In St. John's Island and Lazarus Island off the coast of Singapore exists a field of living and fossil microatolls. Ideally, the corals have multiple concentric rings on their upper surfaces, with each ring formed after a partial coral die off due to a prolonged exposure at extreme low water. The determination of the age and height of the rings enables the reconstruction of Singapore's relative sea level since the 20th century and during the mid-Holocene. 

These sea level indicators are used to validate our Earth system models such as coupled climate models or solid Earth deformation models and the associated modelled relative sea level change since the last deglaciation. The picture was taken on a field trip in connection to the World Climate Research Program (WCRP) Sea Level Conference and the PALSEA Annual Meeting (Paleo Sea Level and Ice Sheets for Earth's Future).

The aerial view shows the Zarnekow polder at the TERENO Northeast observatories near Dargun, Mecklenburg-Vorpommern, which almost completely dried out during the extreme summer of 2018. The photograph was taken while flying over the area for the purpose of analysing the exchange of water and greenhouse gases between earth and atmosphere. The former percolation mire was artificially drained for the first time more than 200 years ago. 

In the 1960s, the fen was completely drained and converted to grassland. In 2004, the now protected landscape was re-wetted. Since fens represent important natural carbon reservoirs capable of retaining large amounts of greenhouse gas, their reclamation can also be seen as a long-term contribution to climate protection. Due to the great heat and drought during the summer of 2018, the polder, which is also an important biotope for waterfowl, fell dry for several months – the underlying cause being climate change. The consequences for the further development of the fen and the associated ecosystem remain unknown.

84.402443°N / 14.675241°E, April 10^th 2020, shortly before one o'clock in the morning: During the MOSAiC expedition in the Arctic Ocean I was on polar bear watch duty at our camp. On this evening we were keen to get out and see something other than the Polarstern, our research vessel. We also felt like trying out how it feels to sleep outside at minus 30°C, drifting on an ice floe across the Arctic Ocean. After the last meeting that evening, we trekked a few kilometers across the pack ice, equipped with thermal mats, tents, sleeping bags and hot drinks. 

We choose a spot behind a pressed ice ridge, out of sight and, above all, away from the noise of the Polarstern whose auxiliary diesel had to provide heat and electricity for man and machine around the clock. Initially grey and lacking in contrast due to cloud cover, this changed around midnight when the prevailing sun, which was far to the north, transformed the ice landscape into an endless expanse of white, various shades of blue and slightly pink glowing ice sculptures. It was only the cold that drove you into your sleeping bag at some point, where it seemed like a "normal" night in a tent. A bit fresh maybe, next time the thermal mat should be a little more than two centimeters thick.

In our GFZ subproject of the international MOSAiC expedition we are dealing with the biogeochemical cycles between ocean, ice and atmosphere. In particular, we are looking at carbon and heat fluxes as well as at methane isotope fractionation during thawing and freezing processes. Our findings contribute to a better understanding of processes in climate projections and provide information on how climate change affects sensitive elements of the Earth's surface system. 

The Láscar volcano, which is about 5,600 m high, is considered the most active volcano in northern Chile. On this day we only had to cover 700 meters to the summit; however, due to the low air pressure the ascent proved extremely strenuous. Apart from that, we also had heavy measuring equipment with us. Even our porters barely managed the ascent so that we scientists had to also take the backpacks and equipment carried by them which meant walking the way multiple times. Once we reached the top we were, however, rewarded by the magnificent scenery of the neighbouring volcanoes of the arid Andes Mountains with a view into the 800 m deep crater of the Láscar volcano at the same time. 

Láscar is a stratovolcano formed by two volcanic structures that have grown together. Its activity is regularly determined by hydromagmatically-triggered steam explosions. It can also emit powerful lava flows and large amounts of ash. A particularly large eruption in 1993 even led to showers of ash on the city of Buenos Aires, 1,500 km away. Due to a smaller eruption that occurred at the Láscar volcano at the end of last year we originally wanted to check the functionality of our measuring station. However, lightning then struck in January – not a rarity due to the exposed location. The power supply, data logger and carbon dioxide sensors had thus to be replaced so that monitoring could continue without interruption. The measured data are transmitted directly to the GFZ in Potsdam via satellite. 

The volcano is also monitored with cameras and via satellites. And, furthermore, the GFZ GFZ Helmholtz Centre for Geosciences in cooperation with its Chilean partners, conducts seismic campaigns and experiments, maps and measures the volcano's geomorphology with drone flights and performs thermal analyses. All of this takes place within the framework of the Integrated Plate Boundary Observatory Chile | IPOC.

Not often do you get to see scenes like this, even as a volcanologist. Together with colleagues from Spain, our team from the GFZ was standing barely half a kilometre from the crater rim on La Palma when the freshly deposited volcanic ash, lapilli and bombs – the glowing pile in the right half of the image – started moving again and plunged back into the crater. The rain of fire impressively demonstrates the importance of maintaining the 400 metres safety distance. The picture was taken in November 2021 at Cumbre Vieja, which had been erupting to over 3 km in height for two months. 

It was already our third trip there. Only days after the eruption began on 19 September of the same year, the GFZ had sent a task force to La Palma to provide a rapid assessment of volcanic eruptions and earthquakes on the island. Together with Spanish institutions, we began to investigate the interaction of the eruption with the quakes and surface deformations. For this purpose, we used seismometers, inclinometers, thermal cameras and drones, as well as images from radar satellites. It was particularly important to record the direction and changes of the lava flows, as they ran through populated territory.

Around 20 million cubic metres of ash fell on the Canary Island of La Palma during the volcanic eruption in 2021. However, this was probably not the cause of the death of these pine trees. Instead, they are evidence of how toxic the volcanic degassing is, particularly due to sulphur dioxide. The dead trunks are located just 250 metres east of one of the 18 craters and help us to track down degassing sites underground.

As part of my EU-funded ERC grant project ‘ROTTnROCK’, we are investigating the effects of such gases and hot, acidic fluids on the stability of craters and volcanic rock. Our observations show that they corrode rocks so that the volcanoes can literally rot from the inside out. We suspect that this is a major cause of unexpected volcanic eruptions and collapses of crater flanks.

We therefore want to understand the process of this so-called alteration in detail, monitor it with innovative drones and satellite sensors, simulate and analyse it in the laboratory and then incorporate these findings into numerical prediction models. 

What looks like a relaxed fishing trip is actually our field campaign on Lake Laach in the Eifel — the most active volcanic lake in Germany. Volcanic gases are continuously rising from the bottom of the lake and we analyse the gases at regular intervals for their composition and concentration in order to detect changes in the activity of the magma system and to better assess the hazards they may pose. 

You can see my colleague, Walter Düsing, lowering a CTD measuring device into the water, which records conductivity and temperature as a function of depth. We use a depth sonar (red sphere) to localise the gas emission points on the lake floor, which can be as deep as 51 metres. We can then steer our underwater drone there to collect gas bubbles, which we analyse in the laboratory. This allows us to find out whether the gas comes e.g., from a magma chamber or the Earth's crust. The yellow box contains a CO2 analyser that we use to determine the diffuse CO2 flux at the lake surface.

Lake Laach is part of the Observatory for Central European Volcanic Provinces, which is operated by the GFZ. Our research is also part of the EU-funded ERC grant project EMERGE which is focusing on the quantification of CO2 emissions in tectonically active areas.

The picture was taken in the Mbeya region in southern Tanzania. Here we are investigating whether indispensable but rare raw materials, so-called "Critical Raw Materials" (CRM), can also be extracted from hot water for geothermal application. The GFZ coordinates the large EU project "CRM-geothermal" with institutions from 14 EU states and six partner countries. One of them is Kenya, and we plan to include further countries in East Africa. 

While working on this crack, which is part of the East African Rift Valley, we could hear the thermal water boiling in the fissures. With the hot springs and the lime stone travertine precipitated from them, it was one of the most interesting study sites of our expedition to Tanzania. 

What many do not know: East Africa is a veritable hotspot for geothermal energy. Kenya has been one of the pioneers in its use since the early 1980s. And in Tanzania, hot water is extracted via boreholes and used for agricultural purposes in a pilot plant. Our aim is to find out in what concentrations the critical raw materials occur, and how they can be extracted in an environmentally friendly and socially acceptable way. 

Spread over many shoulders, we carry our equipment along the crater wall down to Lac Flammarion on Guadeloupe. Our PALAVAS project is part of a French-German cooperation programme. We have everything we need to build a small floating platform, which we will use to drill into the lake bed and lift an 8 meter long sediment core. Why all this effort? To gain a better understanding of the intensive weathering and erosion processes on volcanic islands. This is important because rock weathering over geological time is one of the largest sinks for atmospheric CO₂.

The drill core provides us with valuable information on the deposition of the radioactive beryllium isotope (¹⁰Be), which is carried into the lake by precipitation. This isotope makes it possible to determine the strength and speed of weathering. Rocks of magmatic origin in particular, such as basalt or gabbro, are likely to contribute significantly to CO₂ withdrawal, as they dissolve comparatively quickly when exposed to rainwater. This is why tropical volcanic islands are so interesting for research. The active Souffrière volcano is only a few hundred meters away from this ancient caldera. 

We recovered this ice core in July 2020 during our summer field expedition in South Greenland. Here we are about 75 kilometers west of Narsarsuaq. At the beginning of the expedition our camp was still on snow. Then we experienced three weeks of rapid snowmelt, persistent rain and strong winds of up to 80 kilometers per hour. Soon all the snow had disappeared. All that remained was the bare ice, which is populated by purple ice algae. 

The black color on the top of our drill core is a mixture of minerals and various microorganisms. The dark discoloration is mainly due to the chromophoric purpurogalline pigment that ice algae develop to protect themselves from the high UV radiation. Our project "DEEP PURPLE" deals with all processes that darken the Greenland ice sheet: the physical, the microbial and their complex interaction. The project is financed by the Synergy Grant of the European Research Council. Its significance goes far beyond Europe. When ice and snow darken, they absorb more sunlight and, with this, heat. This accelerates the melting process which, in turn, leads to a rise in sea level.

This very first drill core of the season and many others that followed helped us first to optimize the method of preserving snow and ice and its microbial colonization. All cores eventually drilled in the Greenland ice sheet, usually about one meter long, arrived safely at the GFZ after a long transatlantic boat trip in an industrial freezing container and are now being analysed in detail.

On 18 September 2022, I worked on Sary-Chelek Lake in West Kyrgyzstan together with our GFZ-colleague Jens Mingram and our local driver and technician Igor Tutarev. That day we deployed a logger chain to measure the temperature down to 40 m water depth, fixed with a ground weight at more than 150 m. It is part of our activities within the “Focus Site Central Asia”. 

Based on sediment cores from different Kyrgyz lakes, we try to reconstruct the climatic development of the region in the past to learn for the future. To better understand the formation of seasonally laminated sediments in these paleoclimate archives, we need current data on the weather and from the lake. With my Alexander von Humboldt Foundation Climate Protection fellowship we aim to develop some new monitoring techniques as well as a webpage providing existing information on Kyrgyz lakes.

Speaking of new monitoring techniques: Always have some chocolate with you —not only as a give-away on various occasions as we usually do. This time, fortunately, we had some on board: the tinfoil from the packaging helped us to repair a broken contact spring of an underwater pressure logger.

On this evening in early August 2024, we set up our tents again – on our annual  expedition to the glaciers of the Tien Shan Mountains. This time we spent six days travelling – four days on foot and two working days on site. Here in the far east of Uzbekistan, we have also been measuring how the Pakhtakor glacier is developing since last year. This is part of our CAWa-Green and CLIMWATER research projects, which are investigating the water balance in Central Asia in the wake of climate change. 

Our tasks on site are varied: we read the values from the automatic weather station, which collects data throughout the year. We measure how the height of the glacier has changed using so-called ablation stakes that are inserted in the ice. We also use GPS data to estimate the height, extent and coordinates of the glacier and the glacier tongue. In the past year, the glacier tongue has shrunk by 20 metres and the ice has lost 3 metres in thickness.

It is also important to observe an upstream glacial lake. Such lakes are critical because if their shoreline structures burst, for example due to overload, catastrophic amounts of water suddenly will flow into the valley, potentially threatening people and infrastructure. 

Wine connoisseurs will recognise the Pinot Gris here, geologists spot the soil borer (centre), and we see a ‘long-term experiment to save the climate’. The winemaker has been applying ground basalt rock as a mineral fertiliser to his vineyard in the Palatinate region of Germany for 20 years. An unintended side effect: basalt binds the greenhouse gas CO₂ by accelerating weathering. 

In the mountains, far away from the vines, silicate weathering occurs naturally over geological time scales. It is also known as the ‘Earth's thermostat’, because for millions of years it has kept the temperatures on our planet relatively constant. 

So, should we crush rock on a large scale and spread it on fields where it weathers more quickly? The process removes CO₂ from the atmosphere, could also counteracts ocean acidification and even fertilises the soil. No additional land is needed for this. But to do this, basalt rock would first have to be mined and crushed. The heavy metals it contains could eventually accumulate in the soil. This is where our research comes in: We, Dirk Sachse and Patrick Frings, are interested in the long-term effects of this basalt fertilisation. According to the winemaker, the wine has already improved in taste.

Seldom do we see the mixing of two rivers as clearly as is visible here at the meeting of the Rio Gazamumo and the Rio Gazaunta in Colombia on the eastern flank of the Andes. For somebody like me, who studies processes on the Earth's surface, this is quite impressive. 

Usually, rivers in a specific region are similar to each other. Here, however, one was particularly rich in sediments, probably due to a landslide upstream. While driving by we suddenly saw it: we immediately hit the brakes and set our drone into motion! Right before our eyes was the perfect opportunity to see the carbon cycle in action, so to speak. 

With the sediment, organic carbon e.g. from soils and floodplains is also mobilised. A few thousand years can pass before the carbon from this river reaches the Atlantic Ocean some 1600 kilometres away where it is again stored over geological time. In the meantime, it is deposited, eroded or converted by microbial processes over and over again. Whether rivers end up being carbon sources or carbon sinks depends on the balance of such processes. In the ESKOLA project, we are investigating the effects of such natural Earth surface processes as well as anthropogenic factors on matter fluxes in the Colombian Andes. This research project also serves to strengthen our collaboration with Colombian scientists.

Step by step, we descend 44 metres into the middle of the Telegrafenberg. Here we have set up the prototype of the latest generation of the water sampler developed at the GFZ. The deep well under the glass dome behind the Wirtschaftshof was built back in 1879 to supply water. It was later also used for scientific purposes. At the beginning of the 20th century, for example, gravity measurements carried out there were the first to provide evidence of tidal effects on the Earth's crust.

In March 2023, the well served as a test site for our advanced isotope autosampler. This can work autonomously and independently, but also remotely controlled over many months in the field. The instrument takes strictly separated water samples, filters them and fills them hermetically into sample containers. These samples then undergo isotope analyses in the GFZ laboratories.

The original version of the water sampler from 2016 was only designed to collect rainwater. This latest generation device can also process well and spring water as well as contaminated samples from lakes and rivers. There are currently six, and soon to be ten, such appliances in use worldwide. Meanwhile, we at the GFZ already miss the sporting activity which came with every little thing forgotten at the bottom of the well.

The tape library at the GFZ is part of the server room that was built in the new GeoBioLab in 2021. Each magnetic tape can store between 6 and 12 terabytes of data – and even up to 30 when compressed. They offer the possibility to securely store e.g. little-used data on – compared to HDD hard disks or SSD storage – inexpensive, energy-efficient and particularly durable media.

For example, we save backup data from PCs and servers here. Data from the home directory of users is also stored here after they leave the office. The storage period varies between 60 days and one year, depending on the purpose and agreement. For data from past GFZ projects, it can be 30 years or more.

We also provide an HDD cache area as a fast buffer for not too large amounts of data. Its content is successively written to a free tape after a certain time and is then quasi offline: For reading and writing, the tapes must first be fetched from the magnetic tape library by a robot, inserted into a drive and read from there.