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

John TurnerJohn Turner

OutlineOutline

• Some of the current scientific problems in the Some of the current scientific problems in the area of recent climate change area of recent climate change

• The structure of the programmeThe structure of the programme• ObjectivesObjectives• ImplementationImplementation• Possible links to other SCAR programmes and Possible links to other SCAR programmes and

other organisations/programmesother organisations/programmes

The Recent Pattern of Change Across the The Recent Pattern of Change Across the

AntarcticAntarctic

Faraday Annual Mean Temperature

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02001199819951992198919861983198019771974197119681965196219591956195319501947

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 Why is the Pattern of Recent Change so Different

Across the Arctic and Antarctic?Across the Arctic and Antarctic? Perennial Arctic sea ice - First 4 years versus Last4 years of the satelliteRecord (1979-2000) shows substantial decline

Change in sea ice concentrations from passive microwave satellite data 1979-98. From Zwally et al. 2002.

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 Atmospheric Links Between the Antarctic and the TropicsTropics

The 1987 El Nino JJA Anomalies of:

Stream Function (lines)

Divergent wind (vectors)

The Pole of VariabilityThe Pole of VariabilityWinter SD of Surface PressureWinter SD of Surface Pressure

The Non-linearity of the The Non-linearity of the

LinkagesLinkages However, all ENSO However, all ENSO events are different events are different and span a range of and span a range of states of the states of the tropical Pacifictropical Pacific

Dome C

The classic El Nino The classic El Nino response is for cold response is for cold conditions over the conditions over the Antarctic Peninsula, Antarctic Peninsula, but may events but may events differ from thisdiffer from this

The SAMThe SAM

• Synchronous anomalies of Synchronous anomalies of opposite sign in Antarctica opposite sign in Antarctica and mid-latitudesand mid-latitudes

• The principal mode of The principal mode of variability in the variability in the atmospheric circulation of atmospheric circulation of the SH extratropics & high the SH extratropics & high latitudeslatitudes

• Zonally symmetric or Zonally symmetric or annularannular

• Equivalent barotropicEquivalent barotropic• Leading EOF in many Leading EOF in many

atmospheric fields – MSLP, atmospheric fields – MSLP, heights, temperature and heights, temperature and zonal windzonal wind

850 hPa heights regressed onto the SAM index

Mean sea level pressuretrends1971-2000

www.bas.ac.uk/met/gjma/

Theme 1 - Decadal Time Scale Theme 1 - Decadal Time Scale

VariabilityVariability • Focussing on mechanisms of changeFocussing on mechanisms of change• Time scale of years to centuries – Holocene to Time scale of years to centuries – Holocene to

next 100 yearsnext 100 years• Covers the time scale on which much of the Covers the time scale on which much of the

ocean variability takes placeocean variability takes place• Have extensive ice core data, but atmospheric Have extensive ice core data, but atmospheric

analyses only extend back a few decadesanalyses 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 The Antarctic

Circumpolar WaveCircumpolar Wave

The ACW can be The ACW can be observed in observed in anomalies of sea anomalies of sea ice, sea surface ice, sea surface temperatures and temperatures and mean sea level mean sea level pressure. The ACW pressure. The ACW has a wave number has a wave number two pattern taking two pattern taking 8-10 to circle the 8-10 to circle the Antarctic , giving a Antarctic , giving a periodicity of 4-5 periodicity of 4-5 years at any years at any location. location.

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Theme 2 - Global & Regional SignalsTheme 2 - Global & Regional Signals

in Ice Coresin Ice Cores • Will investigate the routes by which global and regional Will investigate the routes by which global and regional

climate signals arrive at the drilling sitesclimate signals arrive at the drilling sites• Will focus on quantifying the relationships between signals in Will focus on quantifying the relationships between signals in

the cores and measures of the global climate systemthe 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 Will use IPY as a Special Observing Period to investigate the

high resolution spatial variability of accumulation.high resolution spatial variability of accumulation.

• Extensive use will Extensive use will be made of be made of meteorological re-meteorological re-analysis fields and analysis fields and the output of the output of climate model runsclimate model runs

Leader P Mayewski

Theme 3 - Natural & Anthropogenic Theme 3 - Natural & Anthropogenic Forcing on the Antarctic Climate Forcing on the Antarctic Climate

SystemSystem • Will attempt to separate Will attempt to separate

and quantify natural and and quantify natural and anthropogenic changes anthropogenic changes over recent decadesover recent decades

• We will produce a series We will produce a series of predictions for the of predictions for the next century based on next century based on various greenhouse gas various greenhouse gas scenariosscenarios

• A major feature will be A major feature will be the use of regional the use of regional modelsmodels

One prediction of Antarctic temperature change for 2100

Leader J Turner

Theme 4 - The Export of Theme 4 - The Export of

Antarctic Climate SignalsAntarctic Climate Signals • Will examine the means by which Antarctic climate Will examine the means by which Antarctic climate

variability can affect the conditions at more variability can affect the conditions at more northerly latitudesnortherly latitudes

• Strong focus on Antarctic Bottom Water, plus other Strong focus on Antarctic Bottom Water, plus other water masses such as intermediate and mode water masses such as intermediate and mode waterwater

• Will examine the influence of removal of sea iceWill examine the influence of removal of sea ice

• Will consider the Will consider the influence of atmospheric influence of atmospheric variability on water variability on water mass propertiesmass properties

Leader M Meredith

Rationale & Fit to SCAR Strategic Rationale & Fit to SCAR Strategic PlanPlan

• Concerned with the links between the Concerned with the links between the Antarctic and the rest of the climate Antarctic and the rest of the climate system – fits to Earth System approachsystem – fits to Earth System approach

• Should provide advice to organisations Should provide advice to organisations such as IPCCsuch as IPCC

• Addressing questions of great public Addressing questions of great public concern, such as Peninsula warmingconcern, such as Peninsula warming

• Will build a strong oceanographic Will build a strong oceanographic element into SCAR scienceelement into SCAR science

• There is a role for all SCAR nations to There is a role for all SCAR nations to take part – modelling, observational, take part – modelling, observational, cruise datacruise data

Objectives/QuestionsObjectives/Questions• How does variability in tropical and mid-How does variability in tropical and mid-

latitude atmospheric and oceanic latitude atmospheric and oceanic conditions modulate the Antarctic conditions modulate the Antarctic climate?climate?

• What are the mechanisms that transfer What are the mechanisms that transfer the tropical signals to the Antarctic?the tropical signals to the Antarctic?

• What controls the stability of coupled What controls the stability of coupled atmosphere-ocean phenomena, such as atmosphere-ocean phenomena, such as the Antarctic Circumpolar wave and the the Antarctic Circumpolar wave and the Southern Hemisphere Annular Mode?Southern Hemisphere Annular Mode?

• What are the quantitative relationships What are the quantitative relationships that reflect the non-linear linkages that reflect the non-linear linkages between climate signals in ice cores, between climate signals in ice cores, Antarctic sea ice and the Antarctic Antarctic sea ice and the Antarctic atmospheric circulation, and the varying atmospheric circulation, and the varying extra-polar signals?extra-polar signals?

Objectives/QuestionsObjectives/Questions

• Why do the teleconnections between the Why do the teleconnections between the tropics and the Antarctic vary on decadal tropics and the Antarctic vary on decadal timescales?timescales?

• How has the development of the Antarctic How has the development of the Antarctic ozone hole affected the teleconnections?ozone hole affected the teleconnections?

• What has been the impact on the Antarctic What has been the impact on the Antarctic environment of changes in the El Niño-environment of changes in the El Niño-Southern Oscillation over recent decades?Southern Oscillation over recent decades?

• How will Antarctic climate conditions change How will Antarctic climate conditions change on regional and continent-wide scales over on regional and continent-wide scales over the next century as a result of various the next century as a result of various greenhouse gas scenarios and other human greenhouse gas scenarios and other human source emissions into the atmosphere?source emissions into the atmosphere?

External LinksExternal Links

• These will be very important. Possible These will be very important. Possible links will be:links will be:– World Climate Research Programme Climate World Climate Research Programme Climate

Variability (CLIVAR) projectVariability (CLIVAR) project– Climate and Cryosphere (CliC) – particularly Climate and Cryosphere (CliC) – particularly

the Southern Ocean panel and CliC Project the Southern Ocean panel and CliC Project Area 4 – Links Between the Cryosphere and Area 4 – Links Between the Cryosphere and the Global Climate Systemthe Global Climate System

– Intergovernmental Panel on Climate ChangeIntergovernmental Panel on Climate Change– Scientific Committee on Ocean ResearchScientific Committee on Ocean Research– International Geosphere Biosphere International Geosphere Biosphere

Programme PAGESProgramme PAGES

Risks?Risks?• We have to mobilise the Antarctic We have to mobilise the Antarctic

community behind our programme, but community behind our programme, but we’ve had a positive response from the we’ve had a positive response from the scientists who have seen the draft scientists who have seen the draft proposalproposal

• Need to find funding from the main Need to find funding from the main agencies and national bodies, but the agencies and national bodies, but the topics are of great scientific importancetopics are of great scientific importance

• Too ambitious? Hopefully not.Too ambitious? Hopefully not.• The problems are not trivial and we have The problems are not trivial and we have

to be realistic about what we can achieve to be realistic about what we can achieve in 6 yearsin 6 years

Implementation (1)Implementation (1)

• Model runs – global and regional Model runs – global and regional atmosphere only and coupled atmosphere only and coupled atmosphere-ocean modelsatmosphere-ocean models

• Ice cores – many shallow, with a few Ice cores – many shallow, with a few deepdeep

• 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 Will incorporate some successful SCAR

activities, e.g. ITASE, READER, ASPeCT, activities, e.g. ITASE, READER, ASPeCT, ATACATAC

• Work with JCADM over data Work with JCADM over data managementmanagement

Implementation (2)Implementation (2)

• The IPY will be a Special Observing The IPY will be a Special Observing PeriodPeriod

• An opportunity for all SCAR nations An opportunity for all SCAR nations to take partto take part

• Easy to develop links with other Easy to develop links with other programmesprogrammes

• We are considering a workshop We are considering a workshop with CliC in late 2006with CliC in late 2006

SummarySummary

• We are addressing important and timely We are addressing important and timely questions questions

• Could link the Antarctic atmosphere – ocean – Could link the Antarctic atmosphere – ocean – ice communityice community

• Could contribute to IPCC round 5Could contribute to IPCC round 5• Outputs have the potential to be of value to Outputs have the potential to be of value to

other SCAR programmesother SCAR programmes• Still need to build an AGCS communityStill need to build an AGCS community