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Update on the Antarctica and the Global Climate System (AGCS) Programme

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To understand the mechanisms controlling the climate of the ... Deals with ice core data, met, climatology, oceanography, model projections, but not biology. ... – PowerPoint PPT presentation

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Title: Update on the Antarctica and the Global Climate System (AGCS) Programme


1
Update on the Antarctica and the Global Climate
System (AGCS) Programme
  • John Turner
  • British Antarctic Survey

2
The Goals of AGCS
  • To understand the mechanisms controlling the
    climate of the Antarctic its cycles and
    variability
  • To explain why the climate has changed in the
    past roughly the last 20K years since the Last
    Glacial Maximum
  • To predict how the climate of the Antarctic might
    change over the next century under various
    greenhouse gas emission scenarios

3
The Four Themes of AGCS
  • Theme 1 Decadal time scale variability (Dave
    Bromwich)
  • Theme 2 - Global Regional Signals in Ice Cores
    (Paul Mayewski)
  • Theme 3 - Natural Anthropogenic Forcing on the
    Antarctic Climate System (John Turner)
  • Theme 4 - The Export of Antarctic Climate Signals
    (Mike Meredith)

4
The 500 hPa Temperature Trends (deg C/decade)
Over 1979-2001 from ECMWF 40 Year Re-analysis
Project
5
Temperature trends with Depth, 1955-1998
  • Much greater than rate of warming of global ocean
    global change 0.31 C since 1950s
  • Strongly surface-intensified.
  • Decays to around zero by 100m depth.
  • Warming of surf T greater than 0.3 deg per decade.

6
Ice core isotope proxy for temperature
(AD1800-2002)indicates all sites within range
of natural variability
Schneider et al. (2006)
7
Annual Precipitation Trends 1985-2001
PMM5 E40
There are no widespread trends of either sign.
( decade-1)
Monaghan et al. (2006)
8
Loss of ice Shelves Around the Antarctic
Peninsula
Strengthening of the westerlies in recent decades
9
Targets for 2007 and 2008
  • Assessment of the Antarctic element of the IPCC
    Assessment Round 4 model predictions for the next
    century
  • Investigation of the mechanisms responsible for
    changes in the SAM
  • Research into mechanisms behind the
    mid-tropospheric warming above the Antarctic that
    occurred over the last 50 years.
  • Investigation of the current state of the
    Antarctic climate in the context of the last
    several hundred years for purposes of assessing
    natural vs anthropogenic impact.
  • Interference between SAM and ENSO signals in
    Antarctica. Teleconnections between Austral -
    Midlatitudes and the Antarctic (Southern
    S-America, Southern ocean islands, and New
    Zealand)

10
Targets for 2007 and 2008
  • A 200 year array of coastal cores from Antarctica
    including sea-ice extent
  • Marine productivity to understand sea-ice extent
    in proxy record (MS)
  • Quantification of oceanic heat, volume, and fresh
    water fluxes in the southern ocean (Quantifying
    the current mean state)
  • Interaction of the ocean on the ice sheet, ice
    shelves, and the atmosphere at the Antarctic
    margin
  • Understanding the driving mechanisms in the
    Southern Ocean overturning
  • Drifting buoy deployment
  • Contribute to Reanalysis efforts
  • Sea ice thickness
  • Developments of data bases, such as READER

11
The new AGCS newsletter NOTUS
12
AGCS session at EGU, Vienna15-20 April 2007
13
The AGCS White Paper
  • State of the Antarctic and Southern Ocean Climate
    System (SASOCS)
  • Akin to the Arctic Climate Impact Assessment
  • Deals with ice core data, met, climatology,
    oceanography, model projections, but not biology.
  • Covers the last 10,000 years and projections for
    the next 100 years
  • How does it link to the Nature paper and the
    Antarctic Climate Change and the Environment
    work?
  • Publish Exec Summary in EOS?
  • Have a draft ready.

14
The New OCEAN-READER Web Site
15
Science Highlight Meredith Hogg
Links the stronger westerlies and Eddy Kinetic
Energy in the ACC. Increased poleward heat
flux may have played a significant role in the
observed warming of the Southern Ocean
16
Science Highlight John Fyfe
He shows that the latest series of climate models
reproduce the observed mid-depth Southern Ocean
warming since the 1950s if they include
time-varying changes in anthropogenic greenhouse
gases, sulphate aerosols and volcanic aerosols in
the Earths atmosphere. The full effect of
human-induced warming of the Southern Ocean may
not yet to be realized because of volcanic
aerosols
17
Current Work on the 5 KM Warming
Two areas of work - The role of Polar
Stratospheric Clouds (PSCs)- Greater poleward
advection of heat by the atmosphere
18
The Proposed Southern ice ocean model
intercomparison project (SIOMIP)
  • Put forward by Siobhan OFarrell (CSIRO) and Todd
    Arbetter (BAS)
  • Scope - a detailed examination of the sea ice
    components in coupled climate models through a
    comparison with observational data sets.
  • Relevant to AGCS, CliC, ASPECT, The Southern
    Ocean Implementation panel, IPY CASO and SASSI
  • Links with interests in water mass formation
  • But many errors come from the atmospheric forcing

19
The Next 100 Years the Mean of 19 Different
Models
Annual mean surface air temperature changes (deg
per decade) CO2 levels doubled over the next 100
years
20
Thank You
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