Climate response associated with the Southern Annular Mode in the surroundings of Antarctic PeninsulaAndrea F. Carril, Claudio G. Menndez and Antonio Navarra

Spatial trends of the Antarctic Sea-Ice Concentration Contours are trends [%] Left: full trends Right: trends after removing SAM and ENSO (contours give the trends due to SAM and ENSO)

Observed SAM-related variability in SICRegression between seasonal SAM index and SIC (HadISST1), JAS, 1980-1999 (Lefebvre et al. 2004) Shadows * 100 are [%]

Questions marks

Are the last generation CGCMs representing the SAM-related variability appropriately?

Are those models capturing the recent observed warming in the Antarctic Peninsula region?

Is it possible to extract an average picture of the SAM-related variability in a warmer climate?

Is the cryosphere sending signals about climate change?

Based on two IPCC experiments 20C3M climate of the 20th century: Historical run SRES A2 climate change experiment: initial conditions from end of 20C3M, to 2100

Time slides 1970-1999: actual climate 2070-2099: future climate

Selected variables ST, SLP, near surface wind and sea-ice SAM index is the PC-1 geop(500 hPa)

Models documentation is available at www-pcmdi.llnl.gov

Multi-model Control Run

Multi-model Control Run

Multi-model Annual Mean Climate Change Projections

Ice Thickness SINTEXG spring - years 81-130Ice Thickness SINTEXG spring - years 81-130 150 WSea ice thicknessComparison with observations Image courtesy of Enrico Scoccimarro, INGV

Multi-model SAM-Positive Phase-related variability

Climate change projects into the positive phase of the SAM in annual mean conditions

In present climate SAM is particularly strong during the austral spring

In future climate SAM is also strong during the austral spring (and summer)

We are going to explore into the SAM-PP-related variability and its change in a warmer climate

Present climate SAM-PP-related variability SLP SW

Future climate SAM-PP-related variability ST (present conditions) SIV ST (future conditions) SIV

Future climate SAM-PP-related variability

ConclusionsWe extracted a picture of the response of the SAM to increasing GHG in a multi-model ensemble produced in the framework of the 4th IPCC project.

In mean average, SLP climate change projects into the positive phase (PP) of the SAM.

We centered the attention in the surface climate variability associated with the SAM PP and its change in a warmer climate.

Particular attention is on the surroundings of the Antarctic Peninsula

Conclusions (cont.)Over the present climate slice, the multi-model ensemble mean reproduce the regional warming around the AP associated with the SAM.

When increasing GHG, warming in the neighborhoods of the AP (and decreasing of sea-ice volume in the sea-ice edge region) intensifies.

This result suggests that recent observed sea-ice trend around the AP could be associated to anthropogenic forcings.

Surface changes in T and SI are consistent with anomalous atmospheric heat transport associated with circulation anomalies.

Word of warning The confidence in sea-ice anomalies response is limited by the reduced number of models that provides the information and the large inter-model spread.

Even if the large scale response to the SAM variability is an important driver of the AP climate change, in CGCMs the local interactions between the atmosphere, sea and sea-ice are misrepresented.

If the stratospheric ozone recovers the SAM variability could also be affected (Shindell and Schmidt 2004).

We emphasize that the results need to be view with caution, given the weaknesses in the models and the uncertainties related to the future evolution of the O3.

March 2005, preliminary results were presented at IPCC meeting, Hawaii

May 2005, a manuscript was submitted to GRL (in revision)

Following the IPCC schedule December 2005, dead-line to be in press, then to be included in the IPCC AR4

Penguins of the Antarctic Peninsula do not believe on climate models !

SAM vs ENSO related variability

Left: SAM signal Right: ENSO signal

Regression coefficients indicate changes in SIC [%] and T [C] corresponding to 1standard deviation change in the indices

But there is also another important protagonist of our work Let me introduce you Pipo!

Pipo is a penguin who lives in the Antarctic peninsula, in particular, he lives over here, in the Larsen ice shelf region.

And Pipo is really worry because recently, in 2002 there were important collapses of the ice shelves in that region.

But 2002 was not an isolate event, Pipo has a very good memory and he remember several collapses during the last decades and Pipo still remember were was the sea-ice line years ago.

Although those collapses could be seen as isolate extreme events or just as a component of regional decadal variability, maybe it is better to think a little about that. And then, the question arrives