Update on the Antarctica Update on the Antarctica

and the Global and the Global Climate System (AGCS) Climate System (AGCS)

ProgrammeProgrammeJohn TurnerJohn Turner

British Antarctic SurveyBritish Antarctic Survey

The Goals of AGCSThe Goals of AGCS

• To understand the mechanisms To understand the mechanisms controlling the climate of the controlling the climate of the Antarctic – its cycles and variabilityAntarctic – its cycles and variability

• To explain why the climate has To explain why the climate has changed in the past – roughly the last changed in the past – roughly the last 20K years since the Last Glacial 20K years since the Last Glacial MaximumMaximum

• To predict how the climate of the To predict how the climate of the Antarctic might change over the next Antarctic might change over the next century under various greenhouse century under various greenhouse gas emission scenarios gas emission scenarios

The Four Themes of AGCSThe Four Themes of AGCS • Theme 1 – Decadal time scale variability (Dave Bromwich)Theme 1 – Decadal time scale variability (Dave Bromwich)

• Theme 2 - Global & Regional Signals in Ice Cores (Paul Theme 2 - Global & Regional Signals in Ice Cores (Paul Mayewski)Mayewski)

• Theme 3 - Natural & Anthropogenic Forcing on the Theme 3 - Natural & Anthropogenic Forcing on the Antarctic Climate System (John Turner)Antarctic Climate System (John Turner)

• Theme 4 - The Export of Antarctic Climate Signals (Mike Theme 4 - The Export of Antarctic Climate Signals (Mike Meredith)Meredith)

The 500 hPa The 500 hPa TemperaturTemperature Trends e Trends (deg (deg C/decade) C/decade) Over 1979-Over 1979-2001 from 2001 from ECMWF 40 ECMWF 40 Year Re-Year Re-analysis analysis ProjectProject

• Much greater Much greater than rate of than rate of warming of warming of global ocean – global ocean – global change global change 0.31 C since 0.31 C since 1950s1950s

• Strongly surface-Strongly surface-intensified.intensified.

• Decays to around Decays to around zero by 100m zero by 100m depth.depth.

• Warming of surf T Warming of surf T greater than 0.3 greater than 0.3 deg per decade.deg per decade.

Temperature trends with Depth, 1955-1998Temperature trends with Depth, 1955-1998

Ice core isotope proxy for temperature Ice core isotope proxy for temperature (AD1800-2002)(AD1800-2002)

indicates all sites within indicates all sites within range of natural variabilityrange of natural variability

Schneider et al. (2006)

Annual Precipitation Trends: 1985-2001Annual Precipitation Trends: 1985-2001

PMM5 E40PMM5 E40

(% decade-1)

Monaghan et al. (2006)

There are no widespread trends of either sign.

Loss of ice Shelves Around the Loss of ice Shelves Around the Antarctic PeninsulaAntarctic Peninsula

Strengthening of the westerlies in recent decades

• Assessment of the Antarctic element of the IPCC Assessment of the Antarctic element of the IPCC Assessment Round 4 model predictions for the next century Assessment Round 4 model predictions for the next century

• Investigation of the mechanisms responsible for changes in Investigation of the mechanisms responsible for changes in the SAM the SAM

• Research into mechanisms behind the mid-tropospheric Research into mechanisms behind the mid-tropospheric warming above the Antarctic that occurred over the last 50 warming above the Antarctic that occurred over the last 50 years.years.

• Investigation of the current state of the Antarctic climate in Investigation of the current state of the Antarctic climate in the context of the last several hundred years for purposes the context of the last several hundred years for purposes of assessing natural vs anthropogenic impact. of assessing natural vs anthropogenic impact.

• Interference between SAM and ENSO signals in Antarctica. Interference between SAM and ENSO signals in Antarctica. Teleconnections between Austral - Midlatitudes* and the Teleconnections between Austral - Midlatitudes* and the Antarctic “ (*Southern S-America, Southern ocean islands, Antarctic “ (*Southern S-America, Southern ocean islands, and New Zealand”)and New Zealand”)

Targets for 2007 and 2008Targets for 2007 and 2008

• A 200 year array of coastal cores from Antarctica including A 200 year array of coastal cores from Antarctica including sea-ice extentsea-ice extent

• Marine productivity to understand sea-ice extent in proxy Marine productivity to understand sea-ice extent in proxy record (MS)record (MS)

• Quantification of oceanic heat, volume, and fresh water fluxes Quantification of oceanic heat, volume, and fresh water fluxes in the southern ocean (Quantifying the current mean state)in the southern ocean (Quantifying the current mean state)

• Interaction of the ocean on the ice sheet, ice shelves, and the Interaction of the ocean on the ice sheet, ice shelves, and the atmosphere at the Antarctic marginatmosphere at the Antarctic margin

• Understanding the driving mechanisms in the Southern Ocean Understanding the driving mechanisms in the Southern Ocean overturningoverturning

• Drifting buoy deploymentDrifting buoy deployment• Contribute to Reanalysis effortsContribute to Reanalysis efforts• Sea ice thicknessSea ice thickness• Developments of data bases, such as READERDevelopments of data bases, such as READER

Targets for 2007 and 2008Targets for 2007 and 2008

The new AGCS The new AGCS newsletter – newsletter –

NOTUSNOTUS

AGCS session AGCS session at EGU, at EGU, ViennaVienna15-20 April 15-20 April 20072007

The AGCS White PaperThe AGCS White Paper • State of the Antarctic and Southern Ocean Climate State of the Antarctic and Southern Ocean Climate

System (SASOCS)System (SASOCS)• Akin to the Arctic Climate Impact AssessmentAkin to the Arctic Climate Impact Assessment• Deals with ice core data, met, climatology, Deals with ice core data, met, climatology,

oceanography, model projections, but not biology.oceanography, model projections, but not biology.• Covers the last 10,000 years and projections for the Covers the last 10,000 years and projections for the

next 100 yearsnext 100 years• How does it link to the Nature paper and the How does it link to the Nature paper and the

Antarctic Climate Change and the Environment Antarctic Climate Change and the Environment work?work?

• Publish Exec Summary in EOS?Publish Exec Summary in EOS?• Have a draft ready.Have a draft ready.

The New OCEAN-READER Web The New OCEAN-READER Web SiteSite

Science Highlight – Meredith & Science Highlight – Meredith & HoggHogg

Links the stronger westerlies and Eddy Kinetic Energy in the ACC. Increased poleward heat fluxmay have played a significant role in the observed warmingof the Southern Ocean

Science Highlight – John FyfeScience Highlight – John Fyfe He shows that the latest series of climate models reproduce the observed mid-depth Southern Ocean warming since the1950s if they include time-varying changes in anthropogenic greenhouse gases, sulphate aerosols and volcanic aerosolsin the Earth’s atmosphere. The full effect of human-induced warming of theSouthern Ocean may not yet to be realized because of volcanic aerosols

Two areas of work Two areas of work

- The role of Polar - The role of Polar Stratospheric Clouds Stratospheric Clouds (PSCs)(PSCs)

- Greater poleward - Greater poleward advection of heat by advection of heat by the atmospherethe atmosphere

Current Work on the 5 KM Current Work on the 5 KM WarmingWarming

The Proposed The Proposed Southern ice ocean model Southern ice ocean model

intercomparison project (SIOMIP)intercomparison project (SIOMIP) • Put forward by Siobhan O’Farrell (CSIRO) and Todd Put forward by Siobhan O’Farrell (CSIRO) and Todd

Arbetter (BAS)Arbetter (BAS)

• Scope - a detailed examination of the sea Scope - a detailed examination of the sea ice components in coupled climate models ice components in coupled climate models through a comparison with observational through a comparison with observational data sets.data sets.

• Relevant to AGCS, CliC, ASPECT, Relevant to AGCS, CliC, ASPECT, The The Southern Ocean Implementation panelSouthern Ocean Implementation panel, , IPY IPY CASO and SASSICASO and SASSI

• Links with interests in water mass formationLinks with interests in water mass formation• But many errors come from the But many errors come from the

atmospheric forcingatmospheric forcing

The Next 100 Years – the Mean of 19 Different The Next 100 Years – the Mean of 19 Different ModelsModels

Annual mean surface air temperature changes (deg per decade)

CO2 levels doubled over the next 100 years

Thank YouThank You