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Der Hamburg-Tornado vom 7. Juni 2016 – Vorhersage wäre möglich gewesen

11. Juni 2018 - 10:57

Meteorologe Dr. Peter Hoffmann: „Als ich an dem Tag von der S-Bahn nach Hause ging, habe ich das Gewitter gesehen. Es war nicht weit entfernt, ich schätze etwa drei Kilometer. Normalerweise wäre ich stehen geblieben und hätte gewartet, um mir das Schauspiel anzusehen. Denn ich bin auch Storm Chaser und habe in Texas, USA, einmal einen Tornado live gesehen. Aber ich wollte nach Hause, zu meinem kleinen Sohn. So habe ich den Tornado vor meiner eigenen Haustür tatsächlich verpasst!
Hätte ich das nur vorher gewusst. Ich erinnerte mich dann an das Rechenmodell zur Wettervorhersage, mit dem ich während meiner Zeit in Australien gearbeitet hatte. Es ist frei verfügbar, ich hatte es auf meinem Laptop installiert und probierte es kurze Zeit später aus: Die Vorhersage für Hamburg sah vielversprechend aus!“

Zur gleichen Zeit zeichnete auf dem Dach des Geomatikums der Universität Hamburg das Regenradar den Tornado detailliert auf. Für die Meteorologinnen und Meteorologen vom CEN ein seltener Glücksfall, dass er sich im Einzugsgebiet des Hamburger Radars befand.

Meteorologe Prof. Felix Ament: „Unsere Radarbilder sind die einzigen professionellen Aufzeichnungen, auf denen der Tornado im Detail zu sehen ist. Weil nur wenige Gebiete weltweit von hoch aufgelösten Radaren beobachtet werden, verpassen wir diese Ereignisse in der Regel. Von vielen gibt es dann nur Handyvideos im Internet. Durch die wissenschaftlichen Aufzeichnungen wissen wir jetzt genau: Der Hamburg-Tornado dauerte 13 Minuten und legte eine Strecke von 1,3 Kilometern zurück.“

Der Tornado wurde mit der Stärke F1 auf der Fujita-Skala (F0-F5) bewertet, ein eher leichtes Ereignis. Obwohl er in einer dicht besiedelten Gegend auftrat, entstanden nur Sachschäden. Peter Hoffmann passte das bestehende Vorhersage-Modell namens CCAM (Conformal Cubic Atmosphere Model) in mehreren Rechenschritten so an, dass es den Niederschlag mit einer Auflösung von einem Kilometer Maschenweite wiedergeben kann. Startet man das Modell mit den Informationen aus der Nacht vom 6. auf den 7. Juni, 2 Uhr, kann es eine Gewitterzelle über Hamburg gegen 17 Uhr nachmittags mit Potenzial zu einem Tornado vorhersagen. Doch wie exakt ist diese Prognose?

Der Vergleich mit den hoch aufgelösten Daten des Radars vom Geomatikum zeigt: Das Modell hätte das Ereignis bis zu zwölf Stunden vorher, zeitlich auf eine halbe Stunde genau und räumlich mit nur etwa drei Kilometern Abweichung vorhersagen können. Mit einfacher Technik lassen sich also bereits erstaunlich exakte Ergebnisse erzielen. 

Ob sich vorhergesagte Gewitterzellen tatsächlich zu einem Tornado entwickeln, lässt sich aus dem Modell nicht ableiten. Tornados entstehen aus Superzellen, das sind hoch strukturierte Gewitterzellen, die rotieren. Doch Studien aus den USA zeigen, dass sich nur aus 26 Prozent aller Superzellen auch tatsächlich ein Tornado bildet. Für Europa wurde dies noch nicht untersucht. Zur genaueren Analyse müssten kurzfristig aktuelle hoch aufgelöste Radardaten einfließen. Ament und Hoffmann haben gemeinsam mit den Kolleginnen Claire Merker (CEN, MeteoSwiss Zürich) und Katharina Lengfeld (Deutscher Wetterdienst) nur dieses einzelne extreme Ereignis untersucht, für routinemäßige Vorhersagen ist weitere Forschung nötig – Potenzial dafür ist eindeutig vorhanden.


Zum Fachartikel


Kontakt:

Dr. Peter Hoffmann, CEN, Universität Hamburg (bis 04/2018)
Climate Service Center Germany, GERICS (ab 05/2018)
Tel.: 040 226 338 457
peter.hoffmanndummy@hzgdummy2.de

Prof. Dr. Felix Ament, CEN, Universität Hamburg
Tel.: 040-42838 3597
felix.amentdummy@uni-hamburgdummy2.de

Climate pros “made in Hamburg”: 10 years of SICSS Graduate School

29. Mai 2018 - 11:43

“Worldwide, the SICSS is a pioneer when it comes to producing climate professionals who think in interdisciplinary terms,” says Prof. Annette Eschenbach, Academic Director of the School of Integrated Climate System Science, describing the school’s approach. “From the outset we have combined disciplines like meteorology, oceanography and biogeochemistry with economics- and social-sciences-based climate research. By doing so, we ensure the researchers of tomorrow are ready to devise increasingly accurate climate-change forecasts, and to develop sound mitigation and adaptation strategies.”

In the course of a two-year Master’s degree program, SICSS students learn about the fundamentals of the climate system from a natural sciences perspective, as well as the social and economic consequences of climate changes. For example, our doctoral candidates are currently investigating Asian monsoon patterns, calculating the costs of adopting renewable energies, and taking a closer look at the actions of individual countries in the context of difficult negotiations on protecting the global climate. On average, they complete their doctoral studies after only 3.5 years – considerably faster than the national average.

For many SICSS students, Hamburg’s intensive focus on climate research influenced their choice of university. The graduate school is part of the Cluster of Excellence CliSAP (Integrated Climate System Analysis and Prediction), in the context of which not only Universität Hamburg, but also the Max Planck Institute for Meteorology, the Helmholtz Centre Geesthacht and the German Climate Computing Center engage in joint research.

In practice, for PhD candidates like Jana Hinners this means that she can work on datasets from the Helmholtz Centre, or regularly attend events hosted by Hamburg’s KlimaCampus Colloquium. “Here in Hamburg I’m more exposed to the diversity of climate research than I would be in any other city,” says the marine biologist, who previously studied in Berlin and in Lund, Sweden.

Once she’s completed her doctoral studies, Hinners plans to stay in research – like roughly half of all SICSS graduates choose to do. Those who aren’t interested in pursuing an academic career find jobs in commerce, politics or with international organizations. 

SICSS Graduates

Daniele Vieira: Climate Change and Education

“I always wanted to be a professor in Brazil – and I’m sure I will be someday! Right now I’m working for UNESCO in the area ‘education for sustainable development,’ which involves a great deal of international travel.

My four years at the SICSS gave me the ideal preparation. I came to Hamburg because it was important to me to write my dissertation in an international setting and in English – and in a country that’s leading the way in climate research. And Germany’s outstanding reputation in this regard opened a lot of doors for me after I graduated. 

Here I had the chance to compare notes with internationally respected experts, travel to congresses and meetings, and to receive valuable support when it was time to start publishing my own research.  I can’t imagine a better way to spend your doctoral studies!”

PhD in Social Science 2016 
Thesis: Interorganisational Situated Learning in Brazil: An Analysis of the Diffusion of the Brazilian Flex-Fuel Vehicle Mitigation Technology

Ali Hoshyaripour: Aerosol Researcher for Solar Parks

“To explore fundamental research questions at a respected institute, and preferably with a concrete connection to practice; that was my dream. And it came true: today I work at the Karlsruhe Institute of Technology (KIT), where I’m studying the influence of dust particles and volcanic ash, which we call natural aerosols, on weather – and on solar parks.  

As an aerosol researcher, I was able to specialize in volcanic aerosols at the SICSS. At the same time, I was in close contact with the top-quality research being pursued in other disciplines. Here, physicists, engineers, economists, sociologists and journalists all pursue a shared focus: on climate change. At first it was a real challenge for us to understand one another; every discipline has its own jargon. To work together effectively, we had to go far outside our comfort zones and devise a new way of communicating – for me, it was a totally new experience. But it paid off. This ‘side effect’ of the SICSS helped me to build many bridges in my subsequent career.”

PhD in Geosciences 2013, Specialty: Geophysics
Thesis: 
Modulation of ash iron solubility in volcanic eruption plumes

Armine Avagyan: From Hamburg to the UN to New York

“My expectations about doing my PhD at the SICSS were definitely all met. I’m currently working at the United Nations (UN) as an advisor for natural resources and climate change for the FAO, the UN’s Food and Agriculture Organization in New York. Thanks to my time at the SICSS I not only have a solid climate research background; I can also use my scientific knowhow to develop political measures, and to translate them into concrete projects.

The interdisciplinary approach pursued at the SICSS ideally equipped me for my choice of career: we always approached climate change from the standpoints of various disciplines. For instance, in the group we discussed how my findings from the field of soil science could be used by climate modelers, economists or journalists; this gave me new perspectives on my core research question. I learned how to present my work to various types of audience – and how to enter into dialogues with them.” 

PhD in Geosciences 2013, Specialty: Soil Science
Thesis: Spatial variability and seasonal dynamics of dissolved organic matter in surface and soil pore waters in mire-forest landscapes in the Komi Republic, Northwest-Russia

Celebration 10 Years SICSS 
Pressinterviews: 01. Juni 2018
Contact christina.kraetzigdummy@uni-hamburgdummy2.de if you are interested.
Timeslots for interviews: 9.30-10.30 und 12.30-13.30 Uhr
Location: Foyer ESA-Ost, Universität Hamburg, 
Edmund Siemers Allee 1, Flügelbau Ost, Hauptgebäude

Program Celebration (pdf)
Portrait Jana Hinners ©UHH/CEN
Portrait Daniele Vieira ©privat
Portrait Ali Hoshyaripour ©UHH/CEN/Ausserhofer
Portrait Armine Avagyan ©UHH/CEN/Ausserhofer

Presscontact:

Christina Krätzig 
Centrum für Erdsystemforschung und Nachhaltigkeit (CEN)
CEN/CliSAP Outreach
E-Mail: christina.kraetzigdummy@uni-hamburgdummy2.de 
Tel: 42838-4237
Universität Hamburg

The North Sea takes up twice as much CO2 along its coasts as previously thought

15. Mai 2018 - 13:46

As climate researchers at Universität Hamburg’s Center for Earth System Research and Sustainability (CEN), my colleague Maybritt Meyer and I wanted to investigate how much carbon dioxide (CO2) the North Sea absorbs in a year. To do so we needed two main pieces of information: firstly the concentration of CO2 in the air compared to that in the water. If the levels are the same, nothing changes. However, the greater the difference – e.g. a high concentration of carbon dioxide in the air and a low concentration in the water – the higher the “pressure” on the CO2 to dissolve in the water. An international team collected this data during several excursions.

At the same time, wind plays an important role – something we also investigated closely. The more strongly the wind blows, stirring up the water’s surface, the greater the exchange with the atmosphere. By mixing the sea like a whisk, it allows CO2 to be more effectively absorbed. However, there is no comprehensive data from all points in the North Sea, so how can the wind be incorporated into the calculations?

To date, we have relied on data from a relatively coarse resolution global model that describes the wind speed at one grid point every hundred kilometers. We used this information to calculate how quickly or slowly the water is able to absorb carbon dioxide. But at the coasts, the wind is particularly changeable, which means that this data hardly reflects the reality.

34 percent more CO2 uptake for the entire North Sea

Our partners from the Helmholtz Center Geesthacht are investigating the coasts with higher resolution models. Using what is known as downscaling – a complex computer simulation – it is possible to meaningfully fill the gaps in the data for regions for which there is little information. The Center calculated a new wind data set for us with a grid spacing of five to ten kilometers for the entire North Sea.

We compared this data with measurements from four stations – two near the coast and two on drilling platforms in the open sea. The results show: the wind at the coasts has previously been greatly underestimated! The high-resolution data paints a much more accurate picture. For the open sea, the measurements correspond well with the older wind data.

We recalculated the CO2 balance – with astounding results: along the coasts more than twice as much carbon dioxide is absorbed as previously assumed. In a year, the entire North Sea took up 34 percent more of the greenhouse gas than thought.

Acidification is in full swing

But what does that mean? We don’t know when the marine carbon dioxide storage will be full. But the more CO2 an ocean absorbs, the more acidic it becomes. In the North Sea, acidification is in full swing, and the changes in the water’s pH can have a detrimental effect on the plants and animals there: their metabolisms have to adapt, while mussels and crabs can have problems forming their shells.

Using refined methods, we can provide increasingly accurate predictions, many of which demonstrate the dramatic impacts of our actions. Therefore I would like to call on the German Federal Government to adhere to the climate goals agreed in Paris in 2015 and effectively curb greenhouse gas emissions.

This content was first published as a guest article in the newspaper Hamburger Abendblatt in May 2018.

Johannes Pätsch is a computer scientist and North Sea expert at Universität Hamburg’s Center for Earth System Research and Sustainability (CEN).

Go to whole Abendblatt-series.

Possible for the first time: reliable three-month forecasts for European winters

24. April 2018 - 12:22

Three-month forecasts – also known as seasonal forecasts – provide average values for the weather over the next three months. With improved reliability, they could provide valuable data for agriculture and industry alike.

Yet the winter in Europe has always been considered to be too unpredictable, and the North Atlantic Oscillation (NAO) to be too chaotic. However, it’s precisely this interplay of the Icelandic Low and Azores High that greatly influences the winter in many parts of Europe. The NAO works like a giant switch that characterizes the direction of air currents over the Atlantic, an aspect that Dobrynin and his team put to good use. They found that, if we can predict the switch’s current position, it can provide us with valuable insights into future weather development in Europe.

"Very good accuracy rate for the first time."

With the aid of a new method, Dobrynin can now much more reliably predict the NAO’s switching phases: as an analysis of the winters from 2001 to 2017 confirmed, in more than half the cases the forecasts have improved. This marks the first time that a forecast for Europe demonstrated quality comparable to those for the Tropics.

“Though there have been a number of previous international and German projects on seasonal forecasts in Europe, the outcomes weren’t much better than if we had simply guessed,” Dobrynin explains. “Now, for the first time, we’re reaching a very good accuracy rate.”

Teleconnections potentially offer a valuable tool for better forecasts worldwide

To make that happen, the oceanographer uses what are known as “teleconnections”: links between specific regions scattered across the globe and the average weather in other regions. For instance, the amount of October snowfall in Siberia influences the coming winter in Europe, just as the North Atlantic Ocean, higher atmospheric layers and the Arctic do. Though teleconnections are difficult to identify and can also change over time, considering them in the analysis can apparently make three-month forecasts much more accurate – which also means they could potentially offer a valuable tool for better forecasts worldwide.

In the context of a European project, Dobrynin will now use the new method in four different forecasting systems, allowing the new tool and its performance be assessed in real-time. One is the German Climate Forecast System, which, just like the new method, was jointly developed by Universität Hamburg, the Max Planck Institute for Meteorology, the ETH Zurich and Germany’s National Meteorological Service.

Original article: Dobrynin M., Domeisen D. I. V., Müller W. A., Bell L., Brune S., Bunzel F., Düsterhus A., Fröhlich K., Pohlmann H., Baehr J. (2018): Improved teleconnection-based dynamical seasonal predictions of boreal winter. Geophysical Research Letters, 45.

Further information: 

German Climate Forecast System (GCFS): Seasonal Forecasts from Germany’s National Meteorological Service (DWD)

Contact:

Dr. Mikhail Dobrynin
Center for Earth System Research and Sustainability (CEN)
E-Mail: mikhail.dobrynindummy@uni-hamburgdummy2.de
Phone: +49 40 42838-7750
Universität Hamburg

Stephanie Janssen
Center for Earth System Research and Sustainability (CEN)
Outreach
E-Mail: stephanie.janssendummy@uni-hamburgdummy2.de 
Phone: +49 40 42838-7596
Universität Hamburg

New insights into mysterious ice clouds

11. April 2018 - 10:29

On fair days, I can study the subject of my research just by looking out my office window: cirrus clouds, which look like feathers painted on the sky with delicate brushstrokes. They can be found at altitudes of six to fourteen kilometers, are composed of tiny ice crystals, and play a decisive part in the climate system. But we’re only beginning to understand just how they actually work.

To learn more about cirrus clouds, I have developed a measuring instrument that can peer inside ice clouds from the vantage point of a satellite. For the past 13 years, I’ve been trying to convince the European Space Agency (ESA) of the instrument’s value – and now I’ve finally succeeded: in 2022 the “ICI” (Ice Cloud Imager) will be launched into orbit together with the weather satellite MetOp-SG, where it will observe cirrus and other ice clouds for the next twenty years from 800 kilometers above the surface.

Clouds have an enormous influence on our climate. For one thing, they reflect part of the sun’s radiation back into space; for another, they capture part of the heat produced on Earth, which would otherwise dissipate into space. As such, they help shape the temperature on our planet.

That being said, not all clouds are created equal. Low-hanging clouds composed of water droplets reflect more short-wave solar radiation and let the Earth’s long-wave radiation pass through them – we can often feel their cooling effect firsthand. In contrast, cirrus and other clouds made of ice have very different physical properties: they let in more solar radiation and keep more heat near the Earth’s surface; as such, they have more of a warming effect.

The ICI will measure how much of the radiation coming from the surface a given ice cloud allows to pass through. To date, researchers have only been able to gauge this radiation in certain segments of the electromagnetic spectrum: one third of it is released into space before it can be analyzed. The ICI will penetrate this unexplored area and record radiation in the “sub-millimeter range,” i.e., at wavelengths of between 0.5 and 1.5 millimeters.

Thanks to various tests, we know that such measurements can be taken with the sensors available today. For example, together with British researchers we mounted a prototype of the instrument on an airplane and had the craft fly over ice clouds. We’re very satisfied with the results; though there’s still no guarantee that the ICI will work just as smoothly in space, but they’re a promising start.
 
The new data this approach yields will allow us to determine the makeup of a given cloud: how much ice it contains, how large the individual crystals are, and whether there are also water droplets. We need this type of information to refine our climate simulations, which can currently only portray clouds in a very rudimentary form: that’s true for today’s clouds, and even more so for the clouds of tomorrow, which will be affected by climate change. But we don’t yet know if there will be more or fewer ice clouds in the future, if their distribution will change, or if their composition will be altered. Thanks to the ICI we’ll be able to make more accurate predictions – and to follow the first changes “live.”

This content was first published as a guest article in the newspaper Hamburger Abendblatt in April 2018.

Prof. Stefan Bühler is a member of Universität Hamburg’s Center for Earth System Research and Sustainability (CEN) and Managing Director of its Meteorological Institute.  

Go to whole Abendblatt-series.

IPCC appoints new authors: scientists from Hamburg assume important functions for sixth IPCC report (Kopie 1)

9. April 2018 - 11:03

“The IPCC report is an important and, in its form, unique stocktaking of what we know about climate change and its consequences for the environment and for society,” says Prof. Dr. Jochem Marotzke from MPI-M, who will act as a Coordinating Lead Author. Along with Marotzke, three other colleagues from the Max Planck Institute for Meteorology will work on the first part of the report about the physical science basis: Prof. Dr. Victor Brovkin, Dr. Thorsten Mauritsen and Dr. Dirk Notz.

The second part of the report will deal with impacts of climate change on the environment and society, and potential adaption strategies. CEN scientist Prof. Dr. Christian Möllmann was chosen as a Lead Author of the chapter “Europe”. “There is an increasing societal interest to understand which opportunities for action are actually at our disposal in terms of adaptation and mitigation and what their respective advantages and disadvantages are,” explained CEN scientist Prof Dr Herrmann Held, who has been chosen to be a Review Editor for the third part of the report. This part will cover opportunities climate change mitigation and he will work on chapter 17 “Accelerating the transition in the context of sustainable development”. Dr. Oliver Geden, who is a research group leader at the German Institute for International and Security Affairs (SWP) and a guest at MPI-M and The Centre for Globalisation and Governance (CGG) at Universität Hamburg, will also contribute to the third part.  

The IPCC authors assess, compare and integrate all results of the international scientific community. Their reports serve governments as a decision-making tool. The fifth report was published in 2013/2014, ahead of the sixth assessment report, special reports are planned. The special reports will include topics like “Global Warming of 1.5°C”, “Ocean and Cryosphere in a Changing Climate” and “Climate Change and Land”.

Working Group 1: The Physical Science Basis

Prof. Dr. Victor Brovkin, Max Planck Institute for Meteorology. Review Editor chapter 5: “Global carbon and other biogeochemical cycles and feedbacks”.
Prof. Dr. Jochem Marotzke, Max Planck Institute for Meteorology. Coordinating Lead Author chapter 4: “Future global climate: scenario-based projections and near-term information”.
Dr. Thorsten Mauritsen, Max Planck Institute for Meteorology. Lead Author chapter 7: “The Earth´s energy budget, climate feedbacks, and climate sensitivity”.
Dr. Dirk Notz, Max Planck Institute for Meteorology. Lead Author chapter 9: “Ocean, cryosphere, and sea level change”.

Working Group 2: Impacts, Adaptation, and Vulnerability 

Prof. Dr. Christian Möllmann, Center for Earth System Research and Sustainability (CEN), Universität Hamburg. Lead Author chapter 13: “Europe”.

Working Group 3: Mitigation of Climate Change 

Prof. Dr. Hermann Held, Center for Earth System Research and Sustainability (CEN), Universität Hamburg. Review editor chapter 17: “Accelerating the transition in the context of sustainable development”.
Dr. Oliver Geden, who is a research group leader at the German Institute for International and Security Affairs (SWP) and a guest at MPI-M and The Centre for Globalisation and Governance (CGG) at Universität Hamburg, will also contribute to the third part.

This personnel composition is still subject to the proviso that no conflicts of interest between existing functions and a future participation in the IPCC-AR6 are to be found. Candidates chosen by IPCC must have selected characteristics: cutting-edge expertise documented by relevant publications, broad overview of a research field proven by relevant review publications or expert reports, proven coordination and communication skills.

Further information: 

Factsheet: How does the IPCC select its authors? (PDF)

Find more information about the different author categories here.

Contact:

Stephanie Janssen
Universität Hamburg
Press- and public relations
Phone +49 40/ 42838 – 7596
stephanie.janssendummy@uni-hamburgdummy2.de 

Dörte de Graaf
Max Planck Institute for Meteorology
Communication
Phone +49 40/ 41173 - 387
doerte.degraafdummy@mpimet.mpgdummy2.de

IPCC appoints new authors: scientists from Hamburg assume important functions for sixth IPCC report

9. April 2018 - 11:03

“The IPCC report is an important and, in its form, unique stocktaking of what we know about climate change and its consequences for the environment and for society,” says Prof. Dr. Jochem Marotzke from MPI-M, who will act as a Coordinating Lead Author. Along with Marotzke, three other colleagues from the Max Planck Institute for Meteorology will work on the first part of the report about the physical science basis: Prof. Dr. Victor Brovkin, Dr. Thorsten Mauritsen and Dr. Dirk Notz.

The second part of the report will deal with impacts of climate change on the environment and society, and potential adaption strategies. CEN scientist Prof. Dr. Christian Möllmann was chosen as a Lead Author of the chapter “Europe”. “There is an increasing societal interest to understand which opportunities for action are actually at our disposal in terms of adaptation and mitigation and what their respective advantages and disadvantages are,” explained CEN scientist Prof. Dr. Herrmann Held, who has been chosen to be a Review Editor for the third part of the report. This part will cover opportunities climate change mitigation and he will work on chapter 17 “Accelerating the transition in the context of sustainable development”.  

The IPCC authors assess, compare and integrate all results of the international scientific community. Their reports serve governments as a decision-making tool. The fifth report was published in 2013/2014, ahead of the sixth assessment report, special reports are planned. The special reports will include topics like “Global Warming of 1.5°C”, “Ocean and Cryosphere in a Changing Climate” and “Climate Change and Land”.

Working Group 1: The Physical Science Basis

Prof. Dr. Victor Brovkin, Max Planck Institute for Meteorology. Review Editor chapter 5: “Global carbon and other biogeochemical cycles and feedbacks”.
Prof. Dr. Jochem Marotzke, Max Planck Institute for Meteorology. Coordinating Lead Author chapter 4: “Future global climate: scenario-based projections and near-term information”.
Dr. Thorsten Mauritsen, Max Planck Institute for Meteorology. Lead Author chapter 7: “The Earth´s energy budget, climate feedbacks, and climate sensitivity”.
Dr. Dirk Notz, Max Planck Institute for Meteorology. Lead Author chapter 9: “Ocean, cryosphere, and sea level change”.

Working Group 2: Impacts, Adaptation, and Vulnerability 

Prof. Dr. Christian Möllmann, Center for Earth System Research and Sustainability (CEN), Universität Hamburg. Lead Author chapter 13: “Europe”.

Working Group 3: Mitigation of Climate Change 

Prof. Dr. Hermann Held, Center for Earth System Research and Sustainability (CEN), Universität Hamburg. Review editor chapter 17: “Accelerating the transition in the context of sustainable development”. 

This personnel composition is still subject to the proviso that no conflicts of interest between existing functions and a future participation in the IPCC-AR6 are to be found. Candidates chosen by IPCC must have selected characteristics: cutting-edge expertise documented by relevant publications, broad overview of a research field proven by relevant review publications or expert reports, proven coordination and communication skills.

Further information: 

Factsheet: How does the IPCC select its authors? (PDF)

Find more information about the different author categories here.

Contact:

Stephanie Janssen
Universität Hamburg
Press- and public relations
Phone +49 40/ 42838 – 7596
stephanie.janssendummy@uni-hamburgdummy2.de 

Dörte de Graaf
Max Planck Institute for Meteorology
Communication
Phone +49 40/ 41173 - 387
doerte.degraafdummy@mpimet.mpgdummy2.de

Thawing permafrost produces more methane than expected

19. März 2018 - 11:42

Methane (CH4) is a potent greenhouse gas, which is roughly 30 times more harmful to the climate than carbon dioxide (CO2). Both gases are produced in thawing permafrost as dead animal and plant remains are decomposed. However, methane is only formed if no oxygen is available. Until now, it was assumed that larger amounts of greenhouse gases are formed when the ground was dry and well aerated – when oxygen was available. Christian Knoblauch and his colleagues have now demonstrated that water-saturated permafrost soils without oxygen can be twice as harmful to the climate as dry soils – which means the role of methane has been greatly underestimated.

Knoblauch has, for the first time, measured and quantified in the laboratory the long-term production of methane in thawing permafrost. The team had to wait for three years before the approximately forty-thousand-year-old samples from the Siberian Arctic finally produced methane. The team observed the permafrost for a total of seven years: an unprecedented long-term study.

What they found: without oxygen, equal amounts of methane and CO2 are produced. But since methane is a far more potent greenhouse gas, it is more significant. Because methane production couldn’t be measured, it was assumed that in the absence of oxygen only very small amounts of it can be formed. “It takes an extremely long time until stable methane-producing microorganisms develop in thawing permafrost,” explains Knoblauch. “That’s why it was so difficult to demonstrate methane production until now.”

The team has used the new data to improve a computer model that estimates how much greenhouse gas is produced in permafrost in the long term – and they’ve compiled a first forecasts. According to the soil scientist: “The permafrost soils of Northern Europe, Northern Asia and North America could produce up to one gigaton of methane and 37 gigatons of carbon dioxide by 2100.” But there are uncertainties. To what depth will the soil actually thaw by then? Will it be wet or dry? One thing, however, is certain: the new data will enable more accurate predictions about the impacts of thawing permafrost on our climate.

Article:
Knoblauch C, Beer C, Liebner S, Grigoriev M N, Pfeiffer E-M (2018): Methane production as key to the greenhouse gas budget of thawing permafrost; Nature Climate Change, DOI: 10.1038/s41558-018-0095-z

Picture download:

Collection of the samples

Christian Knoblauch with sample

 

Contact:

Dr. Christian Knoblauch
Center for Earth System Research and Sustainability (CEN)
Universität Hamburg
christian.knoblauch@uni-hamburg.de
+49 40 42838 2277

Stephanie Janssen
Presse- und Öffentlichkeitsarbeit
Center for Earth System Research and Sustainability (CEN)
Universität Hamburg
stephanie.janssen@uni-hamburg.de
+49 40 42838 7596

The climate-conscious farmer

13. März 2018 - 12:57

In agriculture, there are various sources of greenhouse gases: tractors emit carbon dioxide, while cattle produce methane. The nitrogen in their liquid and dry manure is an effective fertilizer, but can also transform into nitrous oxide, which is 300 times as harmful to the climate as carbon dioxide. Around the world, whenever someone clears a forest, turns grasslands into pastures, or reduces the amount of humus in their crop soil, they harm the climate. In addition, aspects that may seem trivial can have real consequences: how often farmers till the soil, which crops they plant in which order, and whether they fertilize their soil when it’s wet or dry.

Starting in 2030, the still-forming “grand coalition” of political parties heading Germany’s federal government plans to obligate the agricultural sector to reduce emissions – just like the industrial sector is already forced to do. But who’s going to measure the emissions? Every field, every stall and sty is different; every management decision counts, and not even the farmers themselves can keep track of all the consequences. They do, however, consider the issue to be an important one: this was confirmed in the first survey of German farmers, which we conducted in connection with our research into greenhouse gases in agriculture.

First survey of German farmers on greenhouse gases

The majority of the 254 farmers surveyed rated their own level of knowledge in this area as comparatively low and wanted to receive further information. What’s more: the majority claimed they were willing to do their part to reduce emissions. We were surprised to see just how willing: 70 percent of those surveyed claimed that societal recognition would motivate them to run their farms in an environmentally friendlier manner. 40 percent even considered an emissions tax to be a good thing, most likely because it would affect all farms equally and therefore seemed fair to them. In return, the farmers expected to receive compensation, such as subsidies or a label for climate-friendly products, which could be used to justify charging higher prices.

Yet a tool that could show farmers exactly where the greenhouse gases come from, and how their individual choices affect emissions production, would also be an important aspect. It would need to be straightforward, lightweight and deliver results fast. And that’s exactly where we come in. We’re currently working to modify software that farmers already use – and to calculate emissions by drawing on data that they already collect. For example, sensors on their farm machinery already measure plant growth and indicators of crops’ nutrient supply. Using this data, the management software monitoring the sensors automatically measures the amount of fertilizer distributed, down to a scale of one square meter. If a mathematical model were added, the software could also calculate the amount of greenhouse gases produced. We’re now exploring the feasibility of this option at selected farms. Our vision is that, in the future, every farmer will have access to this additional software feature: first in Germany, and later throughout Europe.

Once that happens, farmers will be able to decide for themselves how to run their farms, where they can reduce emissions, and whether potential crop losses can be compensated for by financial remuneration. In turn, it will also be possible to define, review and implement climate targets for farmers.

This content was first published as a guest article in the newspaper Hamburger Abendblatt on 12th March 2018.

Uwe Schneider is an agricultural economist at Universität Hamburg.

Go to whole Abendblatt-series.

How cities shape the weather

8. März 2018 - 13:52

Urban climate is made up of factors like temperature, wind and humidity. Which is the most interesting?

For me it’s recently become the wind; it’s so changeable. It constantly surprises me when effects don’t occur where I expect them to: a gust of wind doesn’t sweep right around the corner, but instead releases its full force a few meters farther away.

Which is the most important weather factor?

For most people it’s the apparent temperature, which largely determines the comfort factor. We call this thermal comfort, and it mainly consists of air temperature, wind and the surface temperature of the ground and buildings together.

You study urban climate. How does this differ from the climate in the countryside?

When the prevailing “normal” weather in the countryside hits a city, most of the individual weather factors are affected. This is due to the buildings, patchy vegetation, and the characteristics of the various surfaces. Streets and buildings absorb heat during the day, and release that heat when the cooler evening comes. Unlike green areas, sealed surfaces can’t release cooling moisture through evaporation. At the same time, the corners of the buildings make the wind harsher, producing gusts.

In a recently published study, you investigate which urban effects are produced by cities themselves, and which are caused by global climate change, for instance. Why is it important to differentiate?

Once we know which climate change-related phenomena are intensified in cities, future urban planners will be able to implement targeted measures accordingly. But this aspect isn’t always easy to identify: when one of a city’s weather parameters changes, it also changes the other parameters – these are highly complex interactions. That’s why we’re working to clearly identify those factors that cities themselves influence.

Which weather factors fall into that category?

Wind, air temperature, humidity and surface temperature – in other words, factors that make up the thermal comfort – are all significantly changed by cities. In the summertime, the afternoons are much warmer in the city than they are in the surrounding countryside. For example, in Hamburg we record an average of 31 days per year with a high of over 25 degrees Celsius, but only 22 such days in the countryside. When it comes to hotter days, with a high of more than 30 degrees, the average number in the city is six per year – which is twice the number in the surrounding area. For people with health issues, the growing heat could mean real problems – and as climate change progresses, we’re likely to see more and more of these hot days.

Which weather factors aren’t affected?

When it comes to precipitation and hours of sunlight, we haven’t found any differences – at least not in your average major city in Central Europe, which Hamburg is a good example of. In China things can be a very different story; for example, in its metropolises the sunlight is limited due to heavy smog.

What can we do about urban heat if climate change continues?

Open bodies of water and greening efforts can produce a cooling effect; we should try to avoid adding more sealed surfaces. These aspects need to be directly addressed in the context of urban planning – which will improve citizens’ thermal comfort. At a higher level, the City of Hamburg can also help by reducing emissions and doing its part to achieve the globally agreed-upon climate protection goals.

Original article:
Sarah Wiesner, Benjamin Bechtel, Jana Fischereit, Verena Gruetzun, Peter Hoffmann, Bernd Leitl, Diana Rechid, K. Heinke Schlünzen, Simon Thomsen (2018): Is It Possible to Distinguish Global and Regional Climate Change from Urban Land Cover Induced Signals? A Mid-Latitude City Example; Urban Science 2 (1), 12

Enhanced weathering of rocks can help to suck CO₂ out of the air – a little

7. März 2018 - 17:06

“The Paris Agreement calls for a balance between anthropogenic greenhouse gas emissions by sources and removals by sinks in the second half of our century to keep global warming well below 2 degrees Celsius,” says lead-author Jessica Strefler from the Potsdam Institute for Climate Impact Research (PIK). “More than anything else this requires rapid and strong reductions of burning fossil fuels such as coal; but some emissions, for instance from industrial processes, will be difficult to reduce – therefore getting CO2 out of the air and storing it safely is a rather hot topic. The weathering of rocks, as dull as it might seem at first glance, is a scientifically exciting part of this.”

Hence the interest of assessing the economics of enhanced weathering for climate mitigation. Mining and grinding as well as transport and distribution were factored in. “Our calculations show that enhanced weathering could be competitive already at 60 US-dollars per ton of CO2 removed for dunite, but only at 200 US-dollars per ton of CO2 removed for basalt,” says Strefler. “This is roughly double of the carbon prices discussed in the current political debate, and substantially more than cost estimates for afforestation which are at 24 Euros per ton of CO2 removed. This is of course an important obstacle for any future implementation of enhanced weathering.”

India, Brazil, South East Asia, China seem to be the best suited locations

Strategies of carbon dioxide removal come with trade-offs. Planting huge numbers of trees to suck CO2 out of the air and store it in their trunks and branches for instance can come at the expense of land needed for food production. Also, carbon capture and underground storage (CCS) on an industrial scale is not accepted as safe by large parts of the population. Enhanced weathering, the spreading of rock material on land, may be easier to realize. However, dunite – the rock type most discussed amongst experts – contains harmful substances, such as chromium or nickel, that could get released during the process. This is why for the present study dunite is an important benchmark, but the researchers focus on basalt as a more sustainable option.

Current CO2 emissions are around 40 billion tons a year; natural weathering absorbs roughly 1.1 billion tons. Enhanced weathering could remove up to 4.9 billion tons per year if basalt is used, and up to 95 billion tons for dunite, according to the scientists’ calculations. It is likely, however, that in practice and considering all trade-offs, only a fraction of this potential could be realized. The best suited locations are warm and humid regions, particularly in India, Brazil, South East Asia, and China, where almost three quarters of the global potential could be realized. This is substantial, yet the uncertainties involved are also substantial, the scientists stress.

More than 3 billion tons of basalt needed to sequester one billion tons of CO2

“The annual potential of CO2 consumption is defined by the grain size and the weathering rate of the rocks used,” says Thorben Amann from Universität Hamburg’s Institute for Geology, Center for Earth System Research and Sustainability (CEN), he is also lead-author of the study. To sequester one billion tons of CO2, more than 3 billion tons basalt would have to be spread, a mindboggling amount equal to almost half of the current global coal production. Grinding the rocks and spreading the powder over roughly one fifth of global cropland would be necessary, which is believed to be feasible, but – due to the gigantic amount of rocks involved – the costs eventually add up.
“We can say that Enhanced Weathering is not just a crazy idea but could actually help climate policy, yet it is still a challenge to get a precise understanding of the involved processes,” says Amann. “After all, there will be impacts on the agricultural soils, their properties will change, but this can also be beneficial. Basalt for example can actually supply certain nutrients to soils, acting as a natural fertilizer.”

The assessment shows that enhanced weathering especially of basalt rocks could be an attractive option to support climate change mitigation, especially for tropical and subtropical regions, where the CO2 uptake potential is the highest. Yet, given the costs and the mass of rocks that would need to be moved, it can likely provide only a small additional contribution.


Press release by the Potsdam Institute for Climate Impact Research and Universität Hamburg, Center for Earth System Research and Sustainability (CEN)


Article: Jessica Strefler, Thorben Amann, Nicolas Bauer, Elmar Kriegler, Jens Hartmann (2018): Potential and costs of carbon dioxide removal by enhanced weathering of rocks. Environmental Research Letters [doi:10.1088/1748-9326/aaa9c4] (open access)

Weblink to the article

Contact:
Dr. Thorben Amann
Universität Hamburg
Bundesstraße 55
20146 Hamburg
Phone: +49 40 42838-6676
E-Mail: thorben.amann@uni-hamburg.de

For further information please contact:
PIK press office
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