The Antarctica & the Global Climate System (AGCS) Programme John Turner

Outline Some of the current scientific problems in the area of recent climate changeSome of the current scientific problems in the area of recent climate change The structure of the programmeThe structure of the programme ObjectivesObjectives ImplementationImplementation Possible links to other SCAR programmes and other organisations/programmesPossible links to other SCAR programmes and other organisations/programmes

The Recent Pattern of Change Across the Antarctic There have been major environmental changes in the Antarctic Peninsula region over recent decades, but little warming at the surface elsewhere

Why is the Pattern of Recent Change so Different Across the Arctic and Antarctic? Perennial Arctic sea ice - First 4 years versus Last 4 years of the satellite Record ( ) shows substantial decline Change in sea ice concentrations from passive microwave satellite data From Zwally et al The ice extent has been increasing at a rate of 1% per decade over this period.

Global coupling via the THC

Atmospheric Links Between the Antarctic and the Tropics The 1987 El Nino JJA Anomalies of: Stream Function (lines) Divergent wind (vectors)

The Pole of Variability Winter SD of Surface Pressure

The Non-linearity of the Linkages However, all ENSO events are different and span a range of states of the tropical Pacific Dome C The classic El Nino response is for cold conditions over the Antarctic Peninsula, but may events differ from this

The SAM Synchronous anomalies of opposite sign in Antarctica and mid-latitudesSynchronous anomalies of opposite sign in Antarctica and mid-latitudes The principal mode of variability in the atmospheric circulation of the SH extratropics & high latitudesThe principal mode of variability in the atmospheric circulation of the SH extratropics & high latitudes Zonally symmetric or annularZonally symmetric or annular Equivalent barotropicEquivalent barotropic Leading EOF in many atmospheric fields – MSLP, heights, temperature and zonal windLeading EOF in many atmospheric fields – MSLP, heights, temperature and zonal wind 850 hPa heights regressed onto the SAM index

Mean sea level pressure trends /met/gjma/

Theme 1 - Decadal Time Scale Variability Focussing on mechanisms of changeFocussing on mechanisms of change Time scale of years to centuries – Holocene to next 100 yearsTime scale of years to centuries – Holocene to next 100 years Covers the time scale on which much of the ocean variability takes placeCovers the time scale on which much of the ocean variability takes place Have extensive ice core data, but atmospheric analyses only extend back a few decadesHave extensive ice core data, but atmospheric analyses only extend back a few decades Will investigate variability of SO water massesWill investigate variability of SO water masses ENSO links with West Antarctic mass balance Leader D Bromwich

The Antarctic Circumpolar Wave The ACW can be observed in anomalies of sea ice, sea surface temperatures and mean sea level pressure. The ACW has a wave number two pattern taking to circle the Antarctic, giving a periodicity of 4-5 years at any location. Dome C

Theme 2 - Global & Regional Signals in Ice Cores Will investigate the routes by which global and regional climate signals arrive at the drilling sitesWill investigate the routes by which global and regional climate signals arrive at the drilling sites Will focus on quantifying the relationships between signals in the cores and measures of the global climate systemWill focus on quantifying the relationships between signals in the cores and measures of the global climate system A particular focus will be on the non-linearity of the systemA particular focus will be on the non-linearity of the system Will use IPY as a Special Observing Period to investigate the high resolution spatial variability of accumulation.Will use IPY as a Special Observing Period to investigate the high resolution spatial variability of accumulation. Extensive use will be made of meteorological re- analysis fields and the output of climate model runsExtensive use will be made of meteorological re- analysis fields and the output of climate model runs Leader P Mayewski

Theme 3 - Natural & Anthropogenic Forcing on the Antarctic Climate System Will attempt to separate and quantify natural and anthropogenic changes over recent decadesWill attempt to separate and quantify natural and anthropogenic changes over recent decades We will produce a series of predictions for the next century based on various greenhouse gas scenariosWe will produce a series of predictions for the next century based on various greenhouse gas scenarios A major feature will be the use of regional modelsA major feature will be the use of regional models One prediction of Antarctic temperature change for 2100 Leader J Turner

Theme 4 - The Export of Antarctic Climate Signals Will examine the means by which Antarctic climate variability can affect the conditions at more northerly latitudesWill examine the means by which Antarctic climate variability can affect the conditions at more northerly latitudes Strong focus on Antarctic Bottom Water, plus other water masses such as intermediate and mode waterStrong focus on Antarctic Bottom Water, plus other water masses such as intermediate and mode water Will examine the influence of removal of sea iceWill examine the influence of removal of sea ice Will consider the influence of atmospheric variability on water mass propertiesWill consider the influence of atmospheric variability on water mass properties Leader M Meredith

Rationale & Fit to SCAR Strategic Plan Concerned with the links between the Antarctic and the rest of the climate system – fits to Earth System approachConcerned with the links between the Antarctic and the rest of the climate system – fits to Earth System approach Should provide advice to organisations such as IPCCShould provide advice to organisations such as IPCC Addressing questions of great public concern, such as Peninsula warmingAddressing questions of great public concern, such as Peninsula warming Will build a strong oceanographic element into SCAR scienceWill build a strong oceanographic element into SCAR science There is a role for all SCAR nations to take part – modelling, observational, cruise dataThere is a role for all SCAR nations to take part – modelling, observational, cruise data

Objectives/Questions How does variability in tropical and mid- latitude atmospheric and oceanic conditions modulate the Antarctic climate?How does variability in tropical and mid- latitude atmospheric and oceanic conditions modulate the Antarctic climate? What are the mechanisms that transfer the tropical signals to the Antarctic?What are the mechanisms that transfer the tropical signals to the Antarctic? What controls the stability of coupled atmosphere-ocean phenomena, such as the Antarctic Circumpolar wave and the Southern Hemisphere Annular Mode?What controls the stability of coupled atmosphere-ocean phenomena, such as the Antarctic Circumpolar wave and the Southern Hemisphere Annular Mode? What are the quantitative relationships that reflect the non-linear linkages between climate signals in ice cores, Antarctic sea ice and the Antarctic atmospheric circulation, and the varying extra-polar signals?What are the quantitative relationships that reflect the non-linear linkages between climate signals in ice cores, Antarctic sea ice and the Antarctic atmospheric circulation, and the varying extra-polar signals?

Objectives/Questions Why do the teleconnections between the tropics and the Antarctic vary on decadal timescales?Why do the teleconnections between the tropics and the Antarctic vary on decadal timescales? How has the development of the Antarctic ozone hole affected the teleconnections?How has the development of the Antarctic ozone hole affected the teleconnections? What has been the impact on the Antarctic environment of changes in the El Niño- Southern Oscillation over recent decades?What has been the impact on the Antarctic environment of changes in the El Niño- Southern Oscillation over recent decades? How will Antarctic climate conditions change on regional and continent-wide scales over the next century as a result of various greenhouse gas scenarios and other human source emissions into the atmosphere?How will Antarctic climate conditions change on regional and continent-wide scales over the next century as a result of various greenhouse gas scenarios and other human source emissions into the atmosphere?

External Links These will be very important. Possible links will be:These will be very important. Possible links will be: –World Climate Research Programme Climate Variability (CLIVAR) project –Climate and Cryosphere (CliC) – particularly the Southern Ocean panel and CliC Project Area 4 – Links Between the Cryosphere and the Global Climate System –Intergovernmental Panel on Climate Change –Scientific Committee on Ocean Research –International Geosphere Biosphere Programme PAGES

Risks? We have to mobilise the Antarctic community behind our programme, but we’ve had a positive response from the scientists who have seen the draft proposalWe have to mobilise the Antarctic community behind our programme, but we’ve had a positive response from the scientists who have seen the draft proposal Need to find funding from the main agencies and national bodies, but the topics are of great scientific importanceNeed to find funding from the main agencies and national bodies, but the topics are of great scientific importance Too ambitious? Hopefully not.Too ambitious? Hopefully not. The problems are not trivial and we have to be realistic about what we can achieve in 6 yearsThe problems are not trivial and we have to be realistic about what we can achieve in 6 years

Implementation (1) Model runs – global and regional atmosphere only and coupled atmosphere-ocean modelsModel runs – global and regional atmosphere only and coupled atmosphere-ocean models Ice cores – many shallow, with a few deepIce cores – many shallow, with a few deep In-situ met and ocean dataIn-situ met and ocean data Re-analyses of atmospheric conditionsRe-analyses of atmospheric conditions Will incorporate some successful SCAR activities, e.g. ITASE, READER, ASPeCT, ATACWill incorporate some successful SCAR activities, e.g. ITASE, READER, ASPeCT, ATAC Work with JCADM over data managementWork with JCADM over data management

Implementation (2) The IPY will be a Special Observing PeriodThe IPY will be a Special Observing Period An opportunity for all SCAR nations to take partAn opportunity for all SCAR nations to take part Easy to develop links with other programmesEasy to develop links with other programmes We are considering a workshop with CliC in late 2006We are considering a workshop with CliC in late 2006

Summary We are addressing important and timely questionsWe are addressing important and timely questions Could link the Antarctic atmosphere – ocean – ice communityCould link the Antarctic atmosphere – ocean – ice community Could contribute to IPCC round 5Could contribute to IPCC round 5 Outputs have the potential to be of value to other SCAR programmesOutputs have the potential to be of value to other SCAR programmes Still need to build an AGCS communityStill need to build an AGCS community