ETH - IACETH - Knutti, Reto, Prof.

	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 Pressetext.com: 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.

More about my research

Courses

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

Knutti, Reto, Prof.

Media News

Selected recent publications

Quick links

Media, presentations and blog contributions

Publications

New research

Research interests

Courses