Geoengineering What is a bottom-up technology

Research on the evaluation of climate engineering

The one running from May 2013 to May 2019 Priority Program (SPP) 1689 of the German Research Foundation (DFG) examined risks and side effects of so-called "climate engineering". The term Climate Engineering (CE) summarizes technological measures that could be used specifically to lower the atmospheric CO2 concentration or to directly influence the Earth's radiation balance in order to mitigate or compensate for anthropogenic climate change.

Climate engineering and our climate goals - an overdue debate

This brochure was created as part of the public relations work for this priority program. It is intended to contribute to promoting an open-ended social and political debate, informed by the best available knowledge, about the possibilities and risks of the various ideas of climate engineering.

read extracts from the brochure online here ...

  • Stenzel, F., Greve, P., Lucht, W., Tramberend, S., Wada, Y. and Gerten, D. Irrigation of biomass plantations may globally increase water stress more than climate change. Nat Commun 12, 1512 (2021).
  • Klaus, G., Oswald, L., Ernst, A. and Merk, C. (2021)Effects of opinion statements on laypeople's acceptance of a climate engineering technology. Comparing the source credibility of researchers, politicians and a citizens' jury. 
  • Robrecht, S., Vogel, B., Tilmes, S., Müller, R. Potential of future stratospheric ozone loss in the midlatitudes under global warming and sulfate geoengineering. doi: 10.5194 / acp-21-2427-2021 /

How can we still achieve the 1.5 degree goal?

Interactive lecture by Prof. Dr. Andreas Oschlies, GEOMAR Kiel, 09.09.20

  • Robrecht, S., Vogel, B., Tilmes, S., Müller, R. (2020) Potential of future stratospheric ozone loss in the mid-latitudes under climate change and sulfate geoengineering
  • Rickels, W., Quaas, M. F., Ricke, K., Quaas, J., Moreno-Cruz, J., Smulders, S. (2020)
    Who turns the global thermostat and by how much?
  • Kreuter, J., Matzner, N., Baatz, C., Keller, D.P., Markus, T., Wittstock, F., Bernitt, U. and Mengis, N. Unveiling assumptions through interdisciplinary scrutiny: Observations from the German Priority Program on Climate Engineering (SPP 1689).Climatic change (2020).
  • Neuber, F. and Ott, K. The Buying Time Argument within the Solar Radiation Management Discourse. Appl. Sci. 2020, 10, 4637.
  • Amann, T., Hartmann, J., Struyf, E., de Oliveira Garcia, W., Fischer, E. K., Janssens, I., Meire, P. and Schoelynck, J. (2020) Enhanced Weathering and related element fluxes - a cropland mesocosm approach.
  • Matzner, N. and Barben, D. (2020): C.limate Engineering as a Communication Challenge: Contested Notions of Responsibility Across Expert Arenas of Science and Policy.
  • Merk, C., Klaus, G., Pohlers, J., Ernst, A., Ott, K., and Rehdanz, K. (2019): Public Perceptions of Climate Engineering: Laypersons ’Acceptance at Different Levels of Knowledge and Intensities of Deliberation.
  • Klaus, G., A. Ernst, L. Oswald (2019) Psychological factors influencing laypersons' acceptance of climate engineering, climate change mitigation and business as usual scenarios.

Sunday, August 18, 2019, 11 a.m. - 5 p.m.

GEOMAR Helmholtz Center for Ocean Research Kiel, Wischhofstr. 1-3, 24148 Kiel.

Detailed program here ...

  • Rickels, W., C, Merk, F. Reith, D. Keller and A. Oschlies (2019).(Mis) conceptions about modeling of negative emissions technologies. Environ. Res. Lett., Https://
  • Stenzel, F., D. Gerten, C. Werner and J. Jägermeyr (2019)Freshwater requirements of large-scale bioenergy plantations for limiting global warming to 1.5 ° C,Environmental Research Letters 14,

To see at the Kieler Woche in the tent on the "Schlaumachwiese" in front of the GEOMAR.

WEDNESDAY, MAY 15, 2019 // 7.30 p.m. - 10.30 p.m.


The priority program of the German Research Foundation
to Climate Engineering and the Museum für Naturkunde invite you to
public panel discussion.

More information and impressions here.

Climate Engineering: Opportunities and Challenges for Responsible Research and Anticipatory Governance

May 14-16, 2019 in Berlin.

Read and see more ...

  • Boyd, P., C. Vivian, M. Boettcher, F. Chai, J. Cullen, T. Goeschl, R. Lampitt, A. Lenton, A. Oschlies, G. Rau, R. Rickaby, K. Ricke an R Wanninkhof (2019).High Level Review of a Wide Range of Proposed Marine Geoengineering Techniques, Journal Series GESAMP Reports and Studies 98,
  • Irvine, P., K. Emanuel, J. He, L. W. Horowitz, G. Vecchi and D. Keith (2019).Halving warming with idealized solar geoengineering moderate key climate hazards,Nature Climate Changevolume 9, 295-299,
  • Mengis, N., D. P. Keller, W. Rickels, M. Quaas and A. Oschlies (2019).Climate engineering – induced changes in correlations between Earth system variables – implications for appropriate indicator selection, Climate Change,
  • Pfrommer, T., Goeschl, T., Proelss, A. et al. Climatic Change (2019). Establishing causation in climate litigation: admissibility and reliability.
  • Reith, F., W. Koeve, D. P. Keller, J. Getzlaff and A. Oschlies (2019).Meeting climate targets by direct CO2 injections: What price would the ocean have to pay? Earth System Dynamics,
  • Robrecht, S., B. Vogel, J.-U. Grooß, K. Rosenlof, T. Thornberry, A. Rollins, M. Krämer, L. Christensen and R. Müller (2019)Mechanism of ozone loss under enhanced water vapor conditions in the mid-latitude lower stratosphere in Summer, Atmos. Chem. Phys., 10, 5805-5833,

Prof. Dr. Andreas Oschlies // Wednesday, January 16, 2019

See and hear the day before on youtube:

Comic by the Helmholtz Association on the subject of climate engineering:

3 - 5 December 2018, Hamburg, Elsa-Brandström-Haus (

More information and some impressions here ...

Debate on geoengineering on November 28th from 6 p.m. in the Spreepalais in Berlin: (German) // START at 4:02 am

Guests on the podium were the geographer Lili Fuhr from the Heinrich Böll Foundation, the economist Prof. Jan Christoph Minx, PhD from the Mercator Research Institute on Global Commons and Climate Change and the physicist Prof. Dr. Andreas Oschlies from the Helmholtz Center for Ocean Research in Kiel and spokesman for the SPP 1689. Christoph Koch (Stern) and Dr. Mai Thi Nguyen-Kim (freelance science journalist) moderated the event.

Mon / 11/26/2018 / 7.30 p.m. to 9 p.m.
Museum of Natural History Berlin · Invalidenstr. 43 10115 Berlin

On the subject: Climate Engineering - changing the climate with targeted technical interventions. Does that help us?

Discussion event

Prof. Dr. Andreas Oschlies from GEOMAR Helmholtz Center for Ocean Research Kiel and Prof. Dr. Alexander Proelß, lawyer at the University of Hamburg, discuss with the audience.

An event of the Natural History Museum Berlin in cooperation with the SPP 1689 in the framework program for the special exhibition ARTEFAKTE in the Natural History Museum.

Further information and registration:

Third and final annual retreat of the SPP1689 / 2
September 26-28, Buchenau Castle

You can find some impressions here

Reflections from the natural, social and human sciences


  • Knowledge - competence - text

Edited By Nina Janich and Lisa Rhein

The book presents a disciplinary variety of perspectives on uncertainty in science. The focus is on climate research, environmental science and technology assessment. The contributions discuss the reasons and consequences of scientific uncertainty and the corresponding responsibility of science. Communication science, linguistics, philosophy, political science, sociology and economics as well as chemistry and climate science are represented.

The volume documents the unusual cooperation between two priority programs of the German Research Foundation - "Science and the Public" and "Climate Engineering: Risks, Challenges, Opportunities?" - who met with other scientists at a conference at TU Darmstadt for exchange and critical reflection.

  • Beck, Silke; et al. (2018): The politics of anticipation. The IPCC and the negative emissions technologies experience,
  • Beck, Silke, M. Mahony (2018):The IPCC and the new map of science and politics, WIREs Clim Change,
  • Held, Hermann (2018):The economic value of climate information: On the reinterpretation of climate goals under anticipated learning, Uncertainty as a Challenge for Science,
  • Janich, Nina and C. Stumpf (2018):Responsibility under the condition of uncertainty - and what climate scientists understand by it, Uncertainty as a Challenge for Science,
  • Lawrence, Mark G., S. Schäfer, H. Muri, V. Scott, A. Oschlies, N. E. Vaughan, O. Bucher, H. Schmidt, J. Haywood and J. Scheffran (2018):Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals, Nature Communications 9 (3734),
  • Matzner, Nils and D. Barben (2018): Manipulate the climate responsibly? Uncertainty and responsibility in the climate engineering discourse, Uncertainty as a Challenge for Science,
  • Merk, C., Pönitzsch, G. and Rehdanz, K. (2018) Do climate engineering experts display moral-hazard behavior ?, Climate Policy,doi: 10.1080 / 14693062.2018.1494534
  • Neuber, Frederike (2017):Buying Time with Climate Engineering? An analysis of the buying time framing in favor of climate engineering,
  • Oschlies, Andreas (2018):Evaluation of model quality and uncertainties in climate modeling, Uncertainty as a Challenge for Science,
  • Pfrommer, T. (2018):Diverging Regional Climate Preferences and the Assessment of Solar Geoengineering, Discussion Paper Series (654), doi: 10.11588 / heidok.00025204
  • Rickels, W., M. Quaas, K. Ricke, J. Quaas, J. Moreno-Cruz, S. Smulders (2018):Turning the Global Thermostat - Who, When, and How Much?, Kiel Working Paper (2110), much /

A video by Zhihong Zho // July 2018 // Travemünde

The infographics are licensed under the Creative Commons Attribution-NoDerivatives 4.0 International License.

Contrails - how airplanes naturally create clouds

When we look at the sky, we can often see different types of clouds. They differ in their appearance, their development and the length of their existence. The thin, narrow bands of cloud behind airplanes are now also an everyday phenomenon. Some mysterious theories have grown up around these narrow bands of clouds, also known as contrails. Above all, these are speculations about the cause of the contrails, their effects on climate and weather, as well as the influence of substances allegedly released on humans. In fact, there is a closed physical theory behind the appearance, development and duration of existence of the contrails, which describes processes that take place completely without secret substances.

More information can be found here

The SPP 1689 Young Scientist Retreat & Workshop on Interdisciplinary Exchange found inLandhaus Lenzener Elbtalaue, held on April 23-25.

You can find some impressions here

The research project TOMACE, one of the projects within the priority program 1689 »Climate Engineering« started its citizens' forum in January. Participation was only possible by invitation.

More information can be found here ...
You can find some impressions here

  • Ferrer González, Miriam, Tatiana Ilyina, Sebastian Sonntag, Hauke ​​Schmidt (2018):Enhanced Rates of Regional Warming and Ocean Acidification after Termination of Large ‐ scale Ocean Alkalinization, Geophysical Research Letters, doi: 10.1029 / 2018gl077847
  • Keller, D.P., Lenton, A., Littleton, E.W. et al. (2018):The Effects of Carbon Dioxide Removal on the Carbon Cycle, Curr Clim Change Rep, 1-16,
  • Kriegler, M., G. Luderer, N. Bauer, L. Baumstark, S. Fujimori, A. Popp, J. Rogelj, J. Strefler,. P. van Vuuren (2018):Pathways limiting warming to 1.5 ° C: a tale of turning around in no time?Phil. Trans. R. Soc. A 2018 376 20160457,
  • Oliveira-Garcia, W., T. Amann, J. Hartmann (2018):Increasing biomass demand enlarges negative forest nutrient budget areas in wood export regions,Scientific Reports 8 (5280), doi: 10.1038 / s41598-018-22728-5
  • Ott, K. K. (2018):On the Political Economy of Solar Radiation Management,Frontiers in Environmental Science 6, 43,
  • Rickels, W., Reith, F., Keller, D., Oschlies, A., & Quaas, M. F. (2018):Integrated Assessment of Carbon Dioxide Removal, Earth’s Future, 6.
  • Roshan, E., M. M. Khabbazan & H. Held (2018):Cost-Risk Trade-Off of Mitigation and Solar Geoengineering: Considering Regional Disparities Under Probabilistic Climate Sensitivity, Environ. Resource Econ., 1-17,
  • Strefler, Jessica; et al. (2018):Between Scylla and Charybdis: Delayed mitigation narrows the passage between large-scale CDR and high costs, Environmental Research Letters, 13. 044015.
  • Werner, C., H-P. Schmidt, D. Gerten, W. Lucht and C. Kammann (2018):Biogeochemical potential of biomass pyrolysis systems for limiting global warming to 1.5 ° C,Environmental Research Letters 13 (4),
  • Werner, C., H-P. Schmidt, D. Gerten, W. Lucht and C. Kammann (2018):Biogeochemical potential of biomass pyrolysis systems for limiting global warming to 1.5 ° C,Environmental Research Letters 13 (4),

The Coupled Model Intercomparison Project (CMIP; currently in the 6th phase) was organized under the auspices of the World Climate Research Program (WCRP). In order to improve the statements about past, present and future climate changes, the results of global coupled climate models are coordinated, exchanged, analyzed and compared in CMIP. They are a central element of the national and international assessment of climate change (e.g. IPCC reports).

CDRMIP, the Carbon Dioxide Removal Model Intercomparison Project, will now support CMIP in the future. The aim of CDRMIP is to research the potential, challenges and effects of Carbon Dioxide Removal (CDR). To do this, it brings models of the earth system together in a common framework. The CDRMIP experiments are designed to answer questions about CDR-induced “reversibility”, the reaction of the Earth system to direct atmospheric CO2 Examine distance (direct air acquisition and storage) and the CDR potential of proposed designs such as afforestation / reforestation and ocean alkalization.

World Climate Research Program:



  • Keller, D. P., Lenton, A., Scott, V., Vaughan, N. E., Bauer, N., Ji, D., Jones, C. D., Kravitz, B., Muri, H., and Zickfeld, K .:The Carbon Dioxide Removal Model Intercomparison Project (CDR-MIP): Rationale and experimental protocol for CMIP6, Geosci. Model Dev., Https://, 2018
  • Kleinschmitt, C., Boucher, O., and Platt, U. (2018): Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2injection studied with the LMDZ-S3A model, Atmos. Chem. Phys., 18, 2769-2786,
  • Oschlies, Andreas (2018): Solar engineering must take temperature debt into account, Nature 554, 423,
  • Mengis, N., Keller, D. P., and Oschlies, A. (2018): Systematic Correlation Matrix Evaluation (SCoMaE) - a bottom-up, science-led approach to identifying indicators, Earth Syst. Dynam., 9, 15-31,
  • Keller D.P. (2018) Marine Climate Engineering. In: Salomon M., Markus T. (eds) Handbook on Marine Environment Protection. Springer, Cham, doi: 10.1007 / 978-3-319-60156-4_13
  • Strefler, Jessica; et al. (2018): Potential and costs of carbon dioxide removal by enhanced weathering of rocks
  • Sunday, Sebastian; et al. (2018): Quantifying and comparing effects of climate engineering methods on the Earth system, Earth's Future, doi: 10.1002 / 2017EF000620
  • Heck, Vera; et al. (2018): Biomass-based negative emissions difficult to reconcile with planetary boundaries, Nature Climate Change (2018), doi: 10.1038 / s41558-017-0064-y

SPP 1689 WORKSHOP // 22 - 23 Jan 2018 // Potsdam Institute for Climate Impact Research, A56

Terrestrial CO2 Removal: Potentials and tradeoffs in the SDG context

This workshop will look into a set of pertinent questions related to potentials of tCDR methods and their interaction with SDGs. It will bring together SPP 1689 researchers and external experts to increase our holistic understanding of global and regional potentials and side-effects of tCDR as well as to identify future research priorities.
read more and find the agenda here ...

Niemeier, U. and Schmidt, H. (2017): Changing transport processes in the stratosphere by radiative heating of sulfate aerosols, Atmos. Chem. Phys., 17, 14871-14886,

Feng, E. Y .; Koeve, W .; Keller, D. P. and Oschlies, A. (2017): Model-based Assessment of the CO2 Sequestration Potential of Coastal Ocean Alkalinization. In Earth's Future. DOI: 10.1002 / 2017EF000659.

Ferrer-Gonzalez, M. (2017).Climate engineering by enhancement of ocean alkalinity: impacts on the Earth system and a comparison with solar radiation management. PhD thesis, University of Hamburg, Hamburg. doi: 10.17617 / 2.2472753.

Andreas Oschlies, Mark Lawrence, Oliver Geden and Lilly Fuhr about "Failing the carbon budget - what's next? " (Photo)

16 - 18 October 2017, KIEL

Some photographs, more information and the agenda here (english only) ...

  • Tavoni, M., V. Bosetti, S. Shayegh, L. Drouet, J. Emmerling, S. Fuss, T. Goeschl, C. Guivarch, TS Lontzek, V. Manoussi, J. Moreno-Cruz, H. Muri, M. Quaas, W. Rickels, (2017), 'Challenges and Opportunities for Integrated Modeling of Climate Engineering', Nota di Lavoro 38.2017, Milan, Italy: Fondazione Eni Enrico Mattei.
  • Kemena, Tronje Peer; Matthes, Katja; Martin, Thomas; Wahl, Sebastian; Oschlies, Andreas: Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara, Clim Dyn (2017).
  • Keller, D. P., Lenton, A., Scott, V., Vaughan, N. E., Bauer, N., Ji, D., Jones, C. D., Kravitz, B., Muri, H., and Zickfeld, K .: The Carbon Dioxide Removal Model Intercomparison Project (CDR-MIP): Rationale and experimental design, Geosci. Model Dev.Discuss., Https://, in review, 2017.

Climate Engineering Conference 2017

October 9-12, 2017, Berlin


Climate protection needs more researchers and inventors
// Less emissions alone are not enough: CO2 has to be extracted from the atmosphere / By Andreas Mihm

Wilfried Rickels i.a. in the article on

  • Niemeier, Ulrike, Tilmes, Simone:Sulfur injections for a cooler planet,Science 21 Jul 2017, Vol. 357, Issue 6348, pp. 246-248, DOI: 10.1126 / science.aan3317,

  • Lohmann, Ulrike, Gasparini, Blaž:A cirrus cloud climate dial ?,Science 21 Jul 2017, Vol. 357, Issue 6348, pp. 248-249, DOI: 10.1126 / science.aan3325,
  • Kleinschmitt, C., Boucher, O., and Platt, U .: Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2 injection studied with the LMDZ-S3A model, Atmos. Chem. Phys. Discuss., Https://, in review, 2017.

  • Stelzer, Harald (2017): Justifying Climate Engineering?. In: Yearbook for Science and Ethics. Volume 21 (2016). Berlin: De Gruyter, 147-169.

5-7 July 2017 at Buchenau Castle near Fulda / Bad Hersfeld.

Impressions from the retreat here ...

Lena Boysen about "green" climate engineering with trees:

Meeting of young scientists in the SPP 1689 in Malente

Impressions here ...

  • Boysen, Lena; et. al (2017): Trade-offs for food production, nature conservation and climate limit the terrestrial carbon dioxide removal potential. In: Global Change Biology, Accepted Articles, DOI: 10.1111 / gcb.13745
  • Boysen, Lena; et. al (2016): I.mpacts devalue the potential of large-scale terrestrial CO2 removal through biomass plantations. In: Environmental Research Letters, Vol. 11, Letter 9, DOI: 10.1088 / 1748-9326 / 11/9/095010 meta; jsessionid = 325AACE0FC1BCA551F5ABFF7BC15679E.ip-10-40-2-108
  • Montserrat, Francesc; et al. (2017):Olivine Dissolution in Seawater: Implications for CO2 Sequestration through Enhanced Weathering in Coastal Environments.In: Environmental Science & Technology, 51, 3960-3970. DOI: 10.1021 / acs.est.6b05942

The German Meteorological Society (DMG) has published a statement and a brief explanatory text on climate engineering in their "Mitteilungen":