Institute for Atmospheric and Climate Science

Knutti, Reto, Prof.

Reto Knutti

ETH Zürich
Prof. Reto Knutti
Institute for Atmospheric and Climate Science
CHN N 12.1
Universitätstrasse 16
CH-8092 Zürich

Phone: +41 44 632 35 40
Fax: +41 44 633 10 58

Go to group website

Media, presentations and blog contributions

Interviews and media coverage


Full publication list Reto Knutti (includes some in press or submitted)

ResearcherID (Thompson Reuters Web of Science)

Google Scholar

New research


Humans affect extreme weather
Human induced warming has already increased the odds for hot days and heavy precipitation events. This will continue, and the most extreme events are affected most strongly. The study has attracted media attention world wide.
Nature Climate Change: Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes
Aktuelle Wetter-Extreme sind menschgemacht, 3sat nano, April 2015
Es fehlt nicht viel, und es wird extrem heisser, Tagesanzeiger, April 2015
New study links weather extremes to global warming, New York Times, April 2015
Study blames global warming for 75 of very hot days, AP, April 2015
Is it global warming or just the weather?, Economist, April 2015


Has global warming stopped?
Much has been speculated about the reduced surface warming in the last 15 years and the implications for the future. Several papers quantify climate sensitivity and transient response from the most recent data and explain the causes of the warming hiatus, and a number of blog and press articles over several months provide a broader perspective.
Nature Geoscience: Natural variability, radiative forcing and climate response in the recent hiatus reconciled
GRL: Estimating climate sensitivity and future temperature in the presence of natural variability
Nature Geoscience: Energy budget constraints on climate response
ETH News: Why global warming is taking a break
Klimablog: Der Klimawandel pausiert (nicht)
Klimablog: Keine Entwarnung beim Klimawandel
SRF Tagesschau
Tagesanzeiger: Die Klimapause


IPCC AR5, and how to slice the global carbon pie
The Working Group I summary of the Intergovernmental Panel on Climate Change Fifth Assessment Report is published. Some reactions of the media, with a focus on what I think is the most relevant topic: the global carbon budget for the 2°C target.
New York Times: How to Slice a Global Carbon Pie?
BAZ: Das CO2 Budget ist schon fast weg
Presentation of IPCC AR5 at ETH Zurich
Multimedia presentation, AURA Zurich
IPCC AR5 WG1 Summary and drafts of chapters
SRF: Wissenschaft und Politik sind sich einig; SRF Autorenbeitrag, September 2013


Ocean eddies influence weather
A new paper in Nature Geoscience demonstrates that small scale eddies in the ocean can affect the wind, clouds and rainfall.
Nature Geoscience: Imprint of Southern Ocean eddies on winds, clouds and rainfall
Nature Geoscience News & Views: Mesoscale eddy effects
20 Minuten: Auch kleine Meereswirbel ändern das Wetter
Kleine Wasserwirbel beeinflussen das Wetter
Die große Wirkung kleiner Wirbel
Mesoscale ocean eddies impact weather


On the way to four, not two degrees
Several recent reports have highlighted the gap between a pathway to 2°C warming and the political reality. In the report “Klimaziele und Emissionsreduktion - Eine Analyse und politische Vision für die Schweiz“ we review the science and discuss the role that Switzerland could take.
OcCC: Klimaziele und Emissionsreduktion - Eine Analyse und politische Vision für die Schweiz
Interview Sonntagszeitung, November 2012
SF Tageschau
Rendez-vous SR DRS1
Bis zur Jahrhundertwende ohne Emissionen, ETH Life
Klimablog: Immer noch nicht auf dem Weg zum 2-Grad-Ziel
Proclim Climate Press: Ein Klimaziel für die Schweiz – Wieviel Ehrgeiz können wir uns leisten?


Climate models: useful or useless?
In three new papers in Nature Climate we show that some climate projections are surprisingly robust, but overall the uncertainties in projections are not decreasing quickly. Some of the uncertainty is caused by internal climate variability that can be surprisingly large.
Robustness and uncertainties in the new CMIP5 climate model projections, Nature Climate Change 2012
Robust joint projections for humidity and temperature extremes, Nature Climate Change 2012
Communication of the role of natural variability in future North American climate, Nature Climate Change 2012
Klimablog: Hurrikan Sandy und der Nutzen von Klimamodellen


The others should do something first…
In a joint report with INFRAS we consider the implications of different burden sharing approaches for different countries in a scenario where greenhouse gases are reduced globally to reach the 2°C target. The interpretation of “common but differentiated responsibility” of course varies in the different burden sharing proposals, but developed countries will have to reduce emissions quickly in all cases.
Emission pathways to reach 2°C target (PDF)


At least three quarters of warming since 1950 manmade
A new paper in Nature Geoscience demonstrates that the global energy balance provides a strong argument that the observed warming is largely man-made.
Anthropogenic and natural warming inferred from changes in Earth’s energy balance, Nature Geoscience 2011
Nature news: Three-quarters of climate change is man-made
Swissinfo: Bild vom menschlichen Klima-Einfluss komplettiert
WDR Radio Interview
World Radio Switzerland Interview
Scientific American: Three-quarters of climate change is man-made
Physicsworld: Energy balance points to man-made climate change
Discovery News: Human factor huge on climate change
BBC: Climate research bolsters 'action' call to UN talks
ORF: Der Mensch und der Klimawandel
FAZ: Der kostbare Kaffeesatz in den Klimamodellen
Carbonbrief: At least three-quarters of global temperature rise since the 1950s caused by humans
Klimablog: Neue Studie: Der Fussabdruck des Klimawandels


Is two degrees warming still possible?
A new paper in Nature Climate Change shows emission reductions needed for a 2°C warming target.
Long-term climate implications of twenty-first century options for carbon dioxide emission mitigation, Nature Climate Change 2011
Nature research highlight: Out-of-reach goal to limit warming Klimawandel: Zwei-Grad-Ziel "noch erreichbar"
ETH Life: Letzte Chance für verbindliche Treibhausgas-Reduktionen?
Klimablog: Fünf vor zwölf für das 2-Grad-Klimaziel??
Press coverage on the 2°C target before Durban:
Autorenbeitrag NZZ am Sonntag: Das Klima verdüstert sich
Tagblatt: Der Wert der Eisbären
Sonntagszeitung: Nur mit Verzicht funktioniert das nicht
Sonntagszeitung: Die immer gleichen Verlierer
Additional work from the Climate Physics group:
Emission pathways consistent with a 2 °C global temperature limit, Nature Climate Change 2011
UNEP Report: Bridging the Emissions Gap


Swiss climate change scenarios CH2011
In a new comprehensive report we present new climate change scenarios for Switzerland.
Report, summaries and data. Deutsche Zusammenfassung.
Swiss TV: Tagesschau
Teletop TV (starts at 5min 30sec)
DRS Echo der Zeit
World Radio International
Swissinfo: Klimawandel-Szenarien bestätigen Erwärmung
Bund: Klimaschutz greift erst in 40 Jahren
ETH Life: CH2011 – die Klimaentwicklung in der Schweiz
Klimablog: Klimabericht «CH2011» – Forschungswissen für die Praxis aufbereitet


Tropics feel the heat
We show that contrary to popular belief, the warming signal will first emerge from natural variability in the tropics, not in high latitudes. Countries in the tropics are more vulnerable, have difficulties to adapt, but are not causing the climate change problem.
Early onset of significant local warming in low latitude countries, ERL 2011
Perspective by Gabi Hegerl: Global warming: it's not only size that matters
Environmentalresearchweb: Tropics will prove climate change first
Climate Ethics: What Can Science Tell Us?
Klimablog: Die Verlierer im Klima Monopoly


Worst case scenarios
In a new paper we explore potential climate impacts from scenarios with high greenhouse gas emissions that deliberately push the limit of what is plausible.
The response of the climate system to very high greenhouse gas emission scenarios, ERL 2011
ETH Klimablog: Neue Studie: Worst-Case-Klimaszenarien zeigen starke Klimaerwärmung
ETH Life: Viel wärmer als im schlimmsten Fall?
ETH Life: Much warmer than the worst-case scenario?
Environmental Research Web: Going beyond the IPCC ‘worst case’
NZZ: Extreme Annahmen – extremer Klimawandel
Tagesanzeiger: Die Natur würde verrückt spielen
KVMR podcast: Climate models and high emission scenarios


Which climate model prediction should I trust?
Several new papers discuss the problems of setting criteria for a “good” model and the challenges in combining results from multiple climate models.
Should we believe model predictions of future climate change?, Philosophical Transactions of the Royal Society 2008
Challenges in combining projections from multiple models, J. Climate 2010
Model behavior: Science Editor’s Choice to the above paper
The end of model democracy? Climatic Change 2010
Risks of model weighting in multi-model climate projections, J. Climate 2010
Climate model genealogy, GRL 2011
Good Practice Guidance Paper on “Assessing and Combining Multi Model Climate Projections”


How much more carbon for the two degree warming target?
A new study shows that only a small fraction of the fossil fuel reserves can be burnt if a warming of two degrees above preindustrial should be avoided. Peak and equilibrium warming are determined by the total emitted carbon; a tonne of carbon is a tonne of carbon, whether today or in fifty years. Emissions must peak soon and be reduced be at least 50% globally in 2050 to avoid two degree warming.
Nature paper: Greenhouse-gas emission targets for limiting global warming to 2°C
Companion Nature paper: Warming caused by cumulative carbon emissions towards the trillionth tonne
Related commentary by the authors: The exit strategy
Nature News and Views: Too much of a bad thing
Nature Editorial: Time to act
Related essay: The worst-case scenario
Related commentary: Overshoot, adapt and recover
BBC: 'Safe' climate means 'no to coal'
Scientific American: How Much Is Too Much?: Estimating Greenhouse Gas Emissions
ETH Life: How the “2°C target” can be reached
NZZ: Was zählt, ist die kumulierte Menge Kohlendioxid
ETH Life: Wie das «2°C-Ziel» erreicht werden kann
20 Minuten: Klimawandel erreicht kritischen Wert
SF Tagesschau: Studie mahnt zu dringendem Klimaschutz
Spiegel Online: Kritische Klimagrenze ist nur noch schwer zu erreichen


The 2008 Olympics as an aerosol field experiment
An analysis of satellite data shows that the effect of the Chinese government to reduce pollution during the 2008 Beijing Olympics was rather small. The improvement was significant but within the interannual variability range. Atmospheric transport is important for air quality in the city.
GRL paper: Beijing Olympics as an Aerosol Field Experiment
Nature Geoscience News and Views: Brief relief
Wired News: Beijing clean-up was largely ineffective
Science News: China Falls Short on Olympic Cleanup
Physics Today: Smog reduced for Beijing Olympics


How much climate change can be avoided?
New simulations with the a comprehensive high resolution model under strong mitigation scenarios show that about half of the climate change can be avoided by the end of the century. A two degree warming target preserves much of the permafrost and Arctic sea ice.
GRL paper: How much climate change can be avoided by mitigation
Science editor’s choice: How low can we go?
Nature Reports Climate Change Research Highlight: Cuts curb impacts
News New York Times: Emissions Cuts Could Lessen Climate Change
News 20 Minuten: CO2 muss um 70 Prozent gesenkt werden
News Focus Online: Die Zukunft der Arktis


Irreversible climate change
Even if carbon emissions were instantly reduced to zero, most of the climate change that has occurred is irreversible for a thousand years. While some impacts are still uncertain, there are robust predictions for both short term impacts like droughts and long term effects like sea level rise.
PNAS paper: Irreversible climate change due to carbon dioxide emissions
Realclimate background article: Irreversible Does Not Mean Unstoppable
News Swissinfo: Study warns climate change is irreversible
News New Scientist: Effects of climate change now irreversible
News Washington Times: Climate change fallout irreversible
NY Times Dot Earth: The Greenhouse Effect and the Bathtub Effect (worth reading!)
ETH Life: Irreversible climate change
ETH Life: Unwiderruflicher Klimawandel
News Sonntagszeitung: Tausend Jahre Dürre
News NZZ: Lang anhaltende Folgen der Klimaerwärmung
News 20 Minuten: Es gibt kein Zurück

Research interests

My research interests are the changes in the global climate system caused by the growing emissions of anthropogenic greenhouse gases like carbon dioxide. I use numerical models of different complexity, from simple energy balance to three-dimensional coupled climate models that resolve the atmosphere, ocean, land, sea ice and their interactions. In particular, I work on simulation of scenarios for future climate change, the quantification of uncertainties in the climate response, and the development of methods to constrain important feedback processes in the climate system by comparing observations with model results.



Wichtiger Hinweis:
Diese Website wird in älteren Versionen von Netscape ohne graphische Elemente dargestellt. Die Funktionalität der Website ist aber trotzdem gewährleistet. Wenn Sie diese Website regelmässig benutzen, empfehlen wir Ihnen, auf Ihrem Computer einen aktuellen Browser zu installieren. Weitere Informationen finden Sie auf
folgender Seite.

Important Note:
The content in this site is accessible to any browser or Internet device, however, some graphics will display correctly only in the newer versions of Netscape. To get the most out of our site we suggest you upgrade to a newer browser.
More information

© 2015 ETH Zurich | Imprint | Disclaimer | 28 May 2015