Climate Response to a very large volcanic eruption: An Earth System Model Approach Claudia Timmreck and Super Volcano Project Group Max Planck Institute for Meteorology, Hamburg IUGG, Perugia 13 July 2007

Why study super volcanic eruptions with an Earth System Model?

Changes in surface albedo and atmospheric radiation Direct effect on vegetation Massive global cooling over several years (decades) -> Impact on vegetation e.g tropical rainforest Stratospheric warming Changes in atmospheric circulation (AO) and chemical composition (e.g. ozone depletion) Changes in sea level and ocean heat content Impact on the carbon cycle (e.g. change in NPP, marine bioproductivity) Impact on water cycle (e.g. reduced tropical precipitation) Super volcanos constitute extremely strong forcing to all compartments of the Earth system:

The MPI-Met „Super Volcano“ project  A crosscutting project at the MPI for Meteorology with international cooperation groups/super-volcanoes.html The Mission  to understand the complex feedback mechanisms of the earth system  to understand past climate changes  to improve our Earth System Model

The MPI Earth System Model

Simulation of a Super Volcano Eruption with the MPI ESM  Several activities in the frame of the MPI Super Volcano projects ( talk by U. Niemeier, M. Herzog)  Three examples: The initial dispersal and radiative forcing of a Northern Hemisphere mid latitude super volcano: a model study MAECHAM4 Study Impact of Large Tephra Deposit on Vegetation and Climate Pinatubo Simulation with a coupled Atmosphere Ocean GCM

The initial dispersal and radiative forcing of a Northern Hemisphere mid latitude super volcano: a model study (Timmreck and Graf, ACP 2006)  Simulation with the chemsitry climate model MAECHAM4/- CHEM with interactive aerosol and chemistry  Initialization of 1700 MT SO 2 (100 times Pinatubo)

A Yellowstone eruption in summer

winter eruption summer eruption Optical depth  =0.5  m Noninteractive Simulation Interactive Simulation Winter eruptionSummer eruption Winter eruption

Large positive flux anomalies of more than 16 W/m 2 are found in the first months after the eruption at the TOA and of less than -32 W/m 2 at the surface. TOA TOA net flux anomalies [W/m2] Heating rate anomalies [k/day] 3 months after the eruption Surface net flux anomalies [W/m2] Radiative Forcing of a „Yellowstone type“ volcano

Dynamical response in the stratosphere 12 months after the eruption 3 months after the eruption Temperature anomaly [K] GPH anomaly 1st winter SST is prescribed -> only limited information about possible climate effects To study climate sensitivity a multimember ensmble run with an ESM model is necesssary

Impact of Large Tephra Deposit on Vegetation and Climate The Yellowstone eruptions spread volcanic ash over large parts of the North American continent, covering up to 1/3 of the continent with silicate ash of at least 10 cm depth.

Impact of Large Tephra Deposit on Vegetation and Climate  Effect of tephra deposits on vegetation and surface: Dying of vegetation Change of surface fluxes(canopy/ground - air) Change of surface albedo Change of surface and soil hydrology Large and potentially long-lasting impacts on weather, climate and the CO2 cycle on continental and even global scales.

Modelling the effects of tephra  MPI ESM including ECHAM5 (atmosphere), MPIOM (ocean), HAMOCC (marine biogeochemistry) and JSBACH (terrestrial biosphere).  CO2 is transported in the atmosphere and exchanged between the atmosphere and the ocean, resp. land.  Tephra deposit was implemented similar to the treatment of snow in terms of depth and cover fraction  Maximum LAI is a simple function of tephra cover fraction, the actual LAI is modelled in the JSBACH phenology module (allowing for dying of vegetation as well as re-growth).  Surface albedo depends on the fraction of a grid cell covered with tephra and the albedo of ash (set to 0.35).

Distribution of Tephra Deposit for a Yellowstone Super-Eruption Tephra Depth after initial deposit Tephra depth after initial depositTephra depth 5 years after eruption Tephra cover fraction after initial depositTephra cover fraction 5 years after eruption (R. Schnur et al., MPI-M) ^

Preliminary Results, JJA Difference in LAIDifference in Upward CO2 flux Difference in Surface Albedo Differences for JJA taken from three-year averages: (2-4 years after eruption) – (1-3 years before eruption) kg/m 2 /s (R. Schnur et al., MPI-M)

Coupled Pinatubo Atmosphere Ocean Runs

Coupled Volcanic AOGCM runs  We have carried out a series of volcanic simulations with the AOGCM, ECHAM5/MPIOM.  The volcanic radiative forcing is calculated online in the model using a realistic spatial-temporal distribution of aerosol optical parameters derived from satellite observations for the Pinatubo episode. Optical depth in the visible

Net Surface flux anomalies [W/m 2 ]

Surface Temperature Anomalies [K]

 During the winters following the three biggest eruptions in the last decades (Agung, 1963; El Chichón, 1982; and Pinatubo,1991) El Niños took place.  Paleo reconstrcutions (Adams et al, 2003) seem to indicate that large volcanic eruptions help to drive the ocean and atmosphere towards a state in which El Niño conditions are favored. A possible volcanic influence on ENSO Niño 3.4 Case INiño 3.4 Case IIINiño 3.4 Case II Three different cases are selected from a 100 year control run.

Nino 3.4 SST Anomalies for the selected cases Initialization of volcanic forcing in January Initialization of volcanic forcing in June

Conclusions  Our model results cannot support the hypothesis that volcanoes enhance the possibilty of an El Niño event. for a Pinatubo size eruption ->Simulation for a very large volcanic eruption eg.100 times Pinatubo  The dynamical response is highly variable and differs between the selected cases, but also quite strongly between the single ensemble members.  Further analysis is necessary to learn more about the physical mechanisms behind and why the ensemble members behave differently  Ongoing work

Last but not least: The Snowball Earth experiment: An extreme case

The Snowball Earth experiment  Setting TSI to near-zero in ECHAM5/MPI-OM causes a transition from realistic present-day climate to a completely ice-covered state within 15 years;  Super volcanoes might reduce TSI for a couple of years about a certain fraction(1/4 ) Marotzke and Botzet GRL 2007 accepted

A fully coupled ESM simulation of a volcanic super eruption including interactive volcanic aerosol and chemistry. Next steps Impact on marine biogeochemitry (HAMOCC) Coupled aerosol chemistry runs for sulfate and ash El Nino response for a very large volcanic eruption

Thank you very much for your attention and Special thanks to Michael Botzet, Guy Brasseur, Reinhard Budich, Martin Claussen, Monika Esch, Irene Fischer–Bruns, Traute Crueger, Marco Giorgetta, Hans-F. Graf, Stefan Hagemann, Helmuth Haak, Michael Herzog, Daniela Jacob, Johann Jungclaus, Stefan Kinne, Katharina Kurz, Jochem Marotzke, Wolfgang Müller, Ulrike Niemeier, Clive Oppenheimer, Thomas Raddatz, Sebastian Rast, Erich Roeckner, Hauke Schmidt, Reiner Schnur, Joachim Segschneider, Steve Self, Gera Stenchikov, Christiane Textor, Manu Anna Thomas, Martin Wiesner