What science is needed for adaptation? “effective adaptation requires a sound physically- based understanding of climate change, often at levels of detail and confidence not yet achievable.” - Susan Solomon, Chair of IPCC WG 1, and Will Steffen, in review of Australian Climate Change Science Program

What are the most urgent science issues? Aerosol/cloud processes Extreme events Ice sheet dynamics Hydrological cycle (ocean-atmos-cryosphere) Biogeochemical feedbacks Abrupt climate change “observations are critical and urgent” - WCRP workshop on priorities post-IPCC 4AR

84% of “global warming” since 1955 is found in the ocean Levitus et al., 2004 OCEAN LAND ICE SHEETS ATMOSPHERE SEA ICE GLACIERS

Southern Ocean window to the deep sea

Global influence of the Southern Ocean

Future of Southern Ocean CO 2 sink

What controls primary production?

Sea ice: albedo and freshwater budget

Current sea-level rise near the upper end of the IPCC projections – Why? IPCC 2001; IPCC 2007; Rahmstorf et al “Larger values cannot be excluded”

Loss of Antarctic ice Antarctic mass loss increased by 70% in last decade, as a result of warmer air and sea temperatures. Rignot et al., Nature Geoscience, 2008

IPCC 4 th Assessment Report Bindoff, Willebrand et al., IPCC, 2007

Observing a changing ocean with Argo

Warming, no change in tilt

Are recent changes unusual? Post 1970s anomaly in LD accumulation The longest such event in 700 years and one of only 6 events of comparable amplitude

Future of the Southern Ocean Warmer, more precipitation Weaker overturning circulation? More stratified (less nutrient input?) Stronger winds? Less sea ice (fewer krill + krill predators?) Shift of ACC fronts (and habitat?) Increased melt of floating glacial ice (SLR?) More acidic (ecosystem impact?) Less (or the same? Or more?) carbon uptake

What can a new CRC do? Observe the evolving state of the SO (T, S, O, CO2, pH, iron, sea ice, ocean – ice shelf interaction, sea level): what climate trajectory are we on? Likelihood and magnitude of Southern Ocean climate feedbacks (eg carbon, sea ice albedo, overturning circulation)

Summary The Southern Ocean and Antarctica are changing. SO changes will have global impact. Models still fail to capture key SO processes, so nature of future change remains uncertain. Observations are critical for model testing and improvement and to determine climate trajectory. A new centre is well-placed to tackle the most urgent uncertainties in future climate change.