Reto Knutti
Research highlights
The 2°C climate target and COP in Paris
What is an appropriate climate target? Will Paris deliver what it promises?
DownloadUnd jetzt alle, Autorenbeitrag NZZ am Sonntag, November 2015 (PDF, 612 KB)vertical_align_bottom
DownloadAuf dünnem Eis, Sonntagsblick, November 2015 (PDF, 1.6 MB)vertical_align_bottom
Download"Ausreichen wird das nicht", Tagblatt, November 2015 (PDF, 2.6 MB)vertical_align_bottom
Download«Marathon ist ausgeschildert», Tagblatt, Dezember 2015 (PDF, 2.4 MB)vertical_align_bottom
DownloadA scientific critique of the two-degree climate change target, Nature Geoscience (PDF, 1.2 MB)vertical_align_bottom
DownloadUnsinnige Debatte um das 2-Grad-Klimaziel, Meinungsbeitrag Tagesanzeiger, Dezember 2015 (PDF, 241 KB)vertical_align_bottom
external page"Wir sollten jetzt den ersten Schritt machen", Deutschlandfunk, Dezember 2015call_made
external pageScientists just undermined a key idea behind the Paris climate talks, Washington Post, December 2015call_made
external pageThe 2-Degree Warming Limit Is Arbitrary And Beside The Poin, FiveThirtyEight, December 2015call_made
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.
external pageNature Climate Change: Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremescall_made
external pageAktuelle Wetter-Extreme sind menschgemacht, 3sat nano, April 2015call_made
external pageEs fehlt nicht viel, und es wird extrem heisser, Tagesanzeiger, April 2015call_made
external pageNew study links weather extremes to global warming, New York Times, April 2015call_made
external pageStudy blames global warming for 75 of very hot days, AP, April 2015call_made
external pageIs it global warming or just the weather?, Economist, April 2015call_made
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.
DownloadNature Geoscience: Natural variability, radiative forcing and climate response in the recent hiatus reconciled (PDF, 1.6 MB)vertical_align_bottom
DownloadGRL: Estimating climate sensitivity and future temperature in the presence of natural variability (PDF, 931 KB)vertical_align_bottom
DownloadNature Geoscience: Energy budget constraints on climate response (PDF, 414 KB)vertical_align_bottom
ETH News: Why global warming is taking a break
Klimablog: Der Klimawandel pausiert (nicht)
Klimablog: Keine Entwarnung beim Klimawandel
external pageSRF Tagesschaucall_made
DownloadTagesanzeiger: Die Klimapause (PDF, 770 KB)vertical_align_bottom
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.
external pageNew York Times: How to Slice a Global Carbon Pie?call_made
external pageBAZ: Das CO2 Budget ist schon fast wegcall_made
external pagePresentation of IPCC AR5 at ETH Zurichcall_made
external pageMultimedia presentation, AURA Zurichcall_made
external pageIPCC AR5 WG1 Summary and drafts of chapterscall_made
external pageSRF: Wissenschaft und Politik sind sich einig; SRF Autorenbeitrag, September 2013call_made
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.
DownloadNature Geoscience: Imprint of Southern Ocean eddies on winds, clouds and rainfall (PDF, 1014 KB)vertical_align_bottom
DownloadNature Geoscience News & Views: Mesoscale eddy effects (PDF, 493 KB)vertical_align_bottom
external page20 Minuten: Auch kleine Meereswirbel ändern das Wettercall_made
external pageKleine Wasserwirbel beeinflussen das Wettercall_made
external pageDie große Wirkung kleiner Wirbelcall_made
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.
external pageOcCC: Klimaziele und Emissionsreduktion - Eine Analyse und politische Vision für die Schweizcall_made
DownloadInterview Sonntagszeitung, November 2012 (PDF, 2 MB)vertical_align_bottom
external pageSF Tageschaucall_made
external pageRendez-vous SR DRS1call_made
Bis zur Jahrhundertwende ohne Emissionen, ETH Life
Klimablog: Immer noch nicht auf dem Weg zum 2-Grad-Ziel
external pageProclim Climate Press: Ein Klimaziel für die Schweiz – Wieviel Ehrgeiz können wir uns leisten?call_made
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.
DownloadRobustness and uncertainties in the new CMIP5 climate model projections, Nature Climate Change 2012 (PDF, 4.9 MB)vertical_align_bottom
DownloadRobust joint projections for humidity and temperature extremes, Nature Climate Change 2012 (PDF, 1.4 MB)vertical_align_bottom
DownloadCommunication of the role of natural variability in future North American climate, Nature Climate Change 2012 (PDF, 3.8 MB)vertical_align_bottom
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.
DownloadEmission pathways to reach 2°C target (PDF, 988 KB)vertical_align_bottom
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.
DownloadAnthropogenic and natural warming inferred from changes in Earth’s energy balance, Nature Geoscience 2011 (PDF, 470 KB)vertical_align_bottom
external pageNature news: Three-quarters of climate change is man-madecall_made
external pageSwissinfo: Bild vom menschlichen Klima-Einfluss komplettiertcall_made
external pageScientific American: Three-quarters of climate change is man-madecall_made
external pagePhysicsworld: Energy balance points to man-made climate changecall_made
external pageDiscovery News: Human factor huge on climate changecall_made
external pageBBC: Climate research bolsters 'action' call to UN talkscall_made
external pageORF: Der Mensch und der Klimawandelcall_made
external pageFAZ: Der kostbare Kaffeesatz in den Klimamodellencall_made
external pageCarbonbrief: At least three-quarters of global temperature rise since the 1950s caused by humanscall_made
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.
DownloadLong-term climate implications of twenty-first century options for carbon dioxide emission mitigation, Nature Climate Change 2011 (PDF, 572 KB)vertical_align_bottom
external pageNature research highlight: Out-of-reach goal to limit warmingcall_made
external pagePressetext.com: Klimawandel: Zwei-Grad-Ziel "noch erreichbar"call_made
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:
DownloadAutorenbeitrag NZZ am Sonntag: Das Klima verdüstert sich (PDF, 338 KB)vertical_align_bottom
DownloadTagblatt: Der Wert der Eisbären (PDF, 3.8 MB)vertical_align_bottom
DownloadSonntagszeitung: Nur mit Verzicht funktioniert das nicht (PDF, 522 KB)vertical_align_bottom
DownloadSonntagszeitung: Die immer gleichen Verlierer (PDF, 1.7 MB)vertical_align_bottom
Additional work from the Climate Physics group:
external pageEmission pathways consistent with a 2 °C global temperature limit, Nature Climate Change 2011call_made
external pageUNEP Report: Bridging the Emissions Gapcall_made
Swiss climate change scenarios CH2011
In a new comprehensive report we present new climate change scenarios for Switzerland.
external pageReport, summaries and data. Deutsche Zusammenfassung.call_made
external pageSwiss TV: Tagesschaucall_made
external pageDRS Echo der Zeitcall_made
external pageSwissinfo: Klimawandel-Szenarien bestätigen Erwärmungcall_made
DownloadBund: Klimaschutz greift erst in 40 Jahren (PDF, 156 KB)vertical_align_bottom
ETH Life: CH2011 – die Klimaentwicklung in der Schweiz
Klimablog: Klimabericht «CH2011» – Forschungswissen für die Praxis aufbereitet
Tropics feel the heat
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.
DownloadThe response of the climate system to very high greenhouse gas emission scenarios, ERL 2011 (PDF, 1.2 MB)vertical_align_bottom
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?
external pageEnvironmental Research Web: Going beyond the IPCC ‘worst case’call_made
external pageNZZ: Extreme Annahmen – extremer Klimawandelcall_made
external pageTagesanzeiger: Die Natur würde verrückt spielencall_made
DownloadKVMR podcast: Climate models and high emission scenarios (MP3, 2.9 MB)vertical_align_bottom
Which climate model prediction should I trust?
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.
DownloadNature paper: Greenhouse-gas emission targets for limiting global warming to 2°C (PDF, 2.8 MB)vertical_align_bottom
DownloadCompanion Nature paper: Warming caused by cumulative carbon emissions towards the trillionth tonne (PDF, 838 KB)vertical_align_bottom
DownloadRelated commentary by the authors: The exit strategy (PDF, 329 KB)vertical_align_bottom
DownloadNature News and Views: Too much of a bad thing (PDF, 1.5 MB)vertical_align_bottom
DownloadNature Editorial: Time to act (PDF, 1 MB)vertical_align_bottom
DownloadRelated essay: The worst-case scenario (PDF, 1.1 MB)vertical_align_bottom
DownloadRelated commentary: Overshoot, adapt and recover (PDF, 2.1 MB)vertical_align_bottom
external pageBBC: 'Safe' climate means 'no to coal'call_made
external pageScientific American: How Much Is Too Much?: Estimating Greenhouse Gas Emissionscall_made
ETH Life: How the “2°C target” can be reached
external pageNZZ: Was zählt, ist die kumulierte Menge Kohlendioxidcall_made
ETH Life: Wie das «2°C-Ziel» erreicht werden kann
external page20 Minuten: Klimawandel erreicht kritischen Wertcall_made
external pageSF Tagesschau: Studie mahnt zu dringendem Klimaschutzcall_made
external pageSpiegel Online: Kritische Klimagrenze ist nur noch schwer zu erreichencall_made
The 2008 Olympics as an aerosol field experiment
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.
DownloadGRL paper: How much climate change can be avoided by mitigation (PDF, 1.5 MB)vertical_align_bottom
DownloadScience editor’s choice: How low can we go? (PDF, 269 KB)vertical_align_bottom
DownloadNature Reports Climate Change Research Highlight: Cuts curb impacts (PDF, 335 KB)vertical_align_bottom
external pageNews New York Times: Emissions Cuts Could Lessen Climate Changecall_made
external pageNews 20 Minuten: CO2 muss um 70 Prozent gesenkt werdencall_made
external pageNews Focus Online: Die Zukunft der Arktiscall_made
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.
DownloadPNAS paper: Irreversible climate change due to carbon dioxide emissions (PDF, 982 KB)vertical_align_bottom
external pageRealclimate background article: Irreversible Does Not Mean Unstoppablecall_made
external pageNews Swissinfo: Study warns climate change is irreversiblecall_made
external pageNews New Scientist: Effects of climate change now irreversiblecall_made
external pageNews Washington Times: Climate change fallout irreversiblecall_made
external pageNY Times Dot Earth: The Greenhouse Effect and the Bathtub Effect (worth reading!)call_made
ETH Life: Irreversible climate change
ETH Life: Unwiderruflicher Klimawandel
DownloadNews Sonntagszeitung: Tausend Jahre Dürre (PDF, 374 KB)vertical_align_bottom
external pageNews NZZ: Lang anhaltende Folgen der Klimaerwärmungcall_made
external pageNews 20 Minuten: Es gibt kein Zurückcall_made
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.