Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt”...
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Transcript of Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt”...
![Page 1: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/1.jpg)
Alley’s ‘Wally Was Right: Predictive Ability of the North
Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate
Change’Jake Leech
29 Aug 08
![Page 2: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/2.jpg)
Bestiary
![Page 3: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/3.jpg)
Wally’s Arguments
• Greenland proxies all show abrupt climate change
• Greenland data matches Europe data
• Data matches expectations from North Atlantic SST changes
• MOC switching is possible
• Data shows ocean circulation changes
![Page 4: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/4.jpg)
Ice core data
![Page 5: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/5.jpg)
Hemispheric See-Saw
Modelled climate patterns seem to match Voelker data set
![Page 6: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/6.jpg)
See Saw in Data
![Page 7: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/7.jpg)
Response of MOC to freshwater
![Page 8: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/8.jpg)
Sea Ice and Seasonality
![Page 9: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/9.jpg)
Wally’s data
• Young, surface waters are depleted in Cd and C-12, and enriched in C-14
• SH water is “older”
• During cold periods, NH sediments are “older”
![Page 10: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/10.jpg)
Jean’s Data
• Benthic forams have heavier oxygen isotopes in colder water and saltier water, and therefore in denser water.
• Density profiles can be used to reconstruct geostrophic flow through the Florida Straits, which shows changes in MOC.
![Page 11: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/11.jpg)
Jerry’s Data
• Water is stripped of Pa and Th before entering the North Atlantic
• Thorium is stripped out of the water within 20-40 years, before being exported
• Protactinium is stripped out of the water within 100-200 years, after being exported.
![Page 12: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/12.jpg)
Jerry’s Data vs. Forams
![Page 13: Alley’s ‘Wally Was Right: Predictive Ability of the North Atlantic “Conveyor Belt” Hypothesis for Abrupt Climate Change’ Jake Leech 29 Aug 08.](https://reader036.fdocuments.net/reader036/viewer/2022081519/56649ed55503460f94be61ba/html5/thumbnails/13.jpg)
Caveats
• Background state is important.
• Freshwater forcing? Cooling events and freshwater pulses are correlated, but which causes which?
• 1500 year oscillation?