MPI ESM Project Super Volcano Claudia Timmreck, Hauke Schmidt, and super volcano project group 31 May 2007

What is a super eruption ? Super eruptions “are defined to be those eruptions yielding in excess of kg of products (>150 times the mass of the 1991 eruption of Mt. Pinatubo)” (Mason et al, 2004). Super eruptions are estimated to occur with a minimum frequency of 1.4 events/Myr (Mason et al, 2004), but in Earth history there were episodes with higher frequency.

Historic super eruptions  Toba: The super eruption of the Indonesian volcano Toba ± 5 ka BP (Rose and Chesner, 1987; Oppenheimer, 2002) was the largest known Quaternary eruption  Yellowstone: Three super eruptions at Yellowstone are known: the Huckleberry Ridge Tuff eruption with an volume of erupted material of 2500 km Ma ago, the Mesa Falls Tuff eruption with 280 km 3 erupted material 1.3 Ma ago and the Lava Creek Tuff eruption with a volume of 1000 km years ago (e.g., Smith and Siegel, 2000).  Further possible sites for super volcanos: Phlegrean Fields west of Naples, Lake Taupo (NZ), ….

These 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. Yellowstone Volcanic System

Why study super volcanic eruptions? Global scientific questions  What would be the global impact of a present day Yellowstone eruption (USA) or an eruption of the Phlegrean fields (Italy) ? -> Advices for environmental, economic social and political consequences  Was the Young Toba Tuff eruption (74±2kyr BP) responsible for a bottle neck in human population around 70 kyr BP ?  Can super volcanic eruptions trigger ice ages ? This project should help to understand past climate changes.

Why study super volcanic eruptions? Super volcanos constitute extremely strong forcing to all compartments of the Earth system: 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) This project should help to understand the feedback mechanisms of the Earth system.

Impact of Large Tephra Deposit on Vegetation and Climate

 Tephra (Greek: ash): Fragments of rock and magma ejected from volcanic eruptions, ranging in size from 1m.  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  These changes will have large and potentially long-lasting impacts on weather, climate and the CO2 cycle on continental and even global scales.  We use the MPI Earth System Model including ECHAM5 (atmosphere), MPIOM (ocean), HAMOCC (marine biogeoche- mistry) and JSBACH (terrestrial biosphere).

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)

A coupled simulation with MAECHAM5-MPIOM

Coupled ECHAM5MPIOM T63L47–T63L31 comparison Nearly uniform warming in the troposphere (below 200hPa), largest in the tropics (~0.5 K). Above 200 hPa, the difference in temperature is dominated by differences in the mean stratospheric circulation, Reduction in the coupled model temperature bias in the tropopause region and in the tropical stratosphere and upper troposphere. At the high latitudes the bias has changed sign. ECHAM5/MPIOM-ERA40MAECHAM5-ECHAM5 significanceMAECHAM5/MPIOM - ERA40 (M. Giorgetta et al., MPI-M)

The Pinatubo test case: Radiative effects

Temperature anomaly at 50 hPa after Mt. Pinatubo After improvements in the SW scheme, the lower stratospheric temperature response is around 4K that is 3K less than the simulations with original ECHAM5 and is more realistic. (M. A.Thomas, MPI–M) „Old“ ECHAM5 Improved ECHAM5 NCEP Reanalysis

The Pinatubo test case: A possible volcanic effect on ENSO

o  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  We have carried out a series of volcanic experiments with the coupled atmosphere ocean circulation model, the 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.

Nino 3.4 SST anomalies [k] Case 1, JuneCase 1, Jan Case 2, JanCase 2, June (super volcano group, MPI-M)

Conclusions (Pinatubo-ENSO)  Our model results cannot support the hypothesis from Adams et al. (2003) that volcanoes enhance the possibilty of an El Ni ñ o event. Our results point in the opposite direction in accordance with new radiocarbon reconstructions (Druffel et al., 2007).  Ongoing work !!!!!!

 Impact on the carbon cycle : volcanic effect on the net CO 2 bonding in the terrestrial biosphere) Input on ocean biogeochemsitry e.g. Algal blossom (Coupling with HAMMOC is prepared)  Understanding the climate signal of historic eruptions, e.g. 1258, Tambora, less cooling in the temperature proxy as one would expected from the estimated emisssion (together with the MILLENIUM project)  Impact on sea level and ocean heat content „Krakatoa lives forever “   A fully coupled ESM simulation of a volcanic super eruption including interactive volcanic aerosol and chemistry  This model will be useful for other issues (geo-engineering, asteroid impacts, nuclear weapons impact,...) Next steps

Last but not least  The MPI super volcano group is a MPI-M crosscuting project but it is not for MPI-M members only !  All interested scientists are welcome to work and collaborate with us  Further information: groups/super-volcanoes.html or contact: