1. Rapid Climate Change (RAPID) programme Meric Srokosz Southampton Oceanography Centre Natural Environment Research Council (NERC) mas@soc.soton.ac.uk http://rapid.nerc.ac.uk

2. Bermuda Rise marine sediment & Greenland ice core From Adkins et al. (1997) - high deposition rate 20-100cm/kyr Matching the time scales of various palaeo proxies is a problem Records need high temporal resolution and dating accuracy to detect rapid climate change events

3. Impact of THC collapse in numerical models (courtesy Michael Vellinga, Hadley Centre) Temperature change in deg. C if collapse occurs in 2050, mean for first decade relative to pre-industrial (HadCM3)

4. Model predictions of THC changes due to global warming Wide range of predictions from different models Uncertainty within models also not well understood

5. RAPID - Overall objective RAPID aims to investigate and understand the causes of rapid climate change, with a main (but not exclusive) focus on the role of the Atlantic Ocean’s Thermohaline Circulation (THC) paleo data modelling observations Observational focus on North Atlantic NERC £20M 2001-2008

6. RAPID funding 4 Announcements of Opportunity (AO), plus SBRI –Monitoring the Atlantic Meridional Overturning Circulation ~£5M  Specific AO to develop pre-operational “early-warning” system (3 projects)  Working with NSF and NOAA –Joint AO with NWO (Netherlands) & RCN (Norway)  To build on ongoing activities in all three countries, and benefit from a cross-national effort (5 projects) –1st & 2nd “Science” AO (28 projects)  2nd AO focus on synthesis / data assimilation of observations –Small Business Research Initiative (4 projects) Data management ~£1M through NERC data centres

7. Monitoring the Atlantic MOC Cannot measure THC per se but can measure the meridional overturning circulation (MOC) and the associated heat transport Collaboration between NERC - NSF - NOAA –26.5˚N array Bryden / Cunningham (SOC), Marotzke (MPI, Germany), Johns (Miami) & Baringer (AOML) meridional heat transport, Florida Straits current measurements –Deep Western Boundary Current (DWBC) observations - Hughes (POL) Grand Banks and Halifax arrays & Toole (WHOI) WHOI- Bermuda line –Watson (UEA) autosamplers for 129 I –Rossby (URI) Oleander line NY-Bermuda

8. Monitoring the MOC - 26.5˚N & Deep Western Boundary Current (arrays deployed in 2004) Monitoring locations

9. DWBC POL RapidLander BPR Arrays deployed April and August 2004 WAVE = Western Atlantic Variability Experiment

10. Boundary signals in altimetry and models Correlation of high pass filtered altimetry everywhere with that averaged in the northern NE Atlantic (marked in black dots). Places where correlation is not significant at the 95% level are left white (Hughes, POL). Williams & Roussenov (Liverpool) are trying to model these boundary signal at the surface and at depth.

11. 26.5˚N monitoring method Gulf Stream transport - Florida Straits cable Ekman transport - using wind climatology Interior geostrophic flow - mooring array Heat transport - XBT sections, CTD sections

12. Atlantic MOC array at 26.5˚N (deployed Feb/Mar 2004) Western boundary 3 Miami moorings, rest of array SOC moorings

13. Moored profiler D277/8 U. Miami & SOC mooring teams

14. Complete array as deployed February-March 2004 ADCP W EBH5 EB1 EB2 EB3 EBH1 EBH2 EBH3 EBH4 MAR 2 MAR 1 MAR 3 MAR 4 WB4 WB2 WBH 1 WBH 2 WB1 BJ A BJ B BJ E ADCP E Currently being recovered and re-deployed (Darwin and Knorr cruises)

15. D279 SOC cruise to calibrate 26.5N array

16. Monitoring the Atlantic MOC at 26.5˚N Estimate MOC Placing of density profiles (Hirschi et al. GRL 2003) OCCAM FLAME

17. Calibrating sediment cores with modern observations Geostrophic currents from D230 x = current meter Palaeo data from Eirik Ridge sediments on past changes in DWBC Measure DWBC ---- CTD / LADCP sections Bacon (SOC) McCave (Cambridge)

18. Surface fluxes associated with weakening MOC HadCM3 MOC Weakening Composite SOC Flux Dataset NAO Composite Anomalous Heat Flux for 5 year period prior to weakening event Josey et al., 2001, GRL, 28(24), 4543-4546 Josey (SOC)

19. New model for open ocean deep convection Munk gyre problem. Upper ocean currents caused by the wind stress, and intensified at the western boundary, due to frictional effects. Animation shows the flow adapting finite element grid. (2-D: v-velocity comp.) Pain (Imperial College)

20. Where next? MOC observing system seen as key part of N. Atlantic observations by CLIVAR for decadal climate prediction –Recommendation of CLIVAR workshop on Atlantic Predictability 2004 MOC observing system is funded for 4 years (to 2008) –RAPID will provide proof of concept but to detect significant MOC change requires ….. (longer) Potential for further funding in UK, but require: –Successful peer reviewed proposal (submitted by early 2006?) –Continued international collaboration (NOAA, NSF) –Links to other international work in N. Atlantic (e.g. MOVE array at 16˚N, ASOF arrays in northern N. Atlantic)