Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene...
-
Upload
lauren-manning -
Category
Documents
-
view
220 -
download
1
Transcript of Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene...
![Page 1: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/1.jpg)
Pliocene Climate Modelling, and the onset of Northern Hemisphere
Glaciation
1) The Pliocene
2) Expansion of Greenland glaciation in the Late Pliocene – uncertainties.
3) Uplift and North American Pliocene glacial inception.
4) Impact of changing Cenozoic ice sheets on climate sensitivity.
![Page 2: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/2.jpg)
Zachos et al, Nature, 2001
Orientation…
![Page 3: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/3.jpg)
From Rainer ZahnFrom Rainer ZahnLegacy of ODP.Legacy of ODP.
Climate evolution - the last 5 million yearsClimate evolution - the last 5 million years
![Page 4: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/4.jpg)
Expansion in Greenland glaciation at ~2.75 Ma
Bartoli et al, EPSL, 2005
![Page 5: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/5.jpg)
The “mid-Pliocene” ~3.3 – 3.0 Ma
Enhanced CO2: ‘Best’ estimate 360 – 400ppmv
Reconstructions of: e.g. vegetation, ice, SST
Haywood et al, Geoscientific Model Development, 2010
![Page 6: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/6.jpg)
“The mid-Pliocene represents an accessible example of a world that is similar in many respects to what models estimate could be the Earth of the late 21st Century.
Taken together, the average of the warmest times during the mid-Pliocene presents a view of the equilibrium state of a globally warmer world, in which atmospheric CO2 concentrations were likely higher than pre-industrial values”.
Jansen et al. 2007 chapter 6, pages 440 to 442.
![Page 7: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/7.jpg)
A palaeoclimate modellers paradise
![Page 8: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/8.jpg)
(1) Closure of Panama Seaway
(2) Tectonic Uplift
(3) Termination of ‘Permanent El Nino’
(4) Decrease in CO2
4 main hypotheses
![Page 9: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/9.jpg)
(1) Closure of Panama Seaway
Ruddiman, p163
Bartoli et al, 2005
![Page 10: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/10.jpg)
(2) Tectonic Uplift
Ruddiman and Kutzbach, 1989
Parrish et al, 2007
![Page 11: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/11.jpg)
(3) Termination of ‘Permanent El Nino’
e.g. Wara et al, 2005
Molnar and Cane, 2002
Fedorov et al, 2010
![Page 12: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/12.jpg)
(4) Decrease in CO2
Seki et al, EPSL, 2010
Raymo et al, Geology, 1988
Changes in weathering/uplift:
![Page 13: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/13.jpg)
Pliocene Control:
Modern continental configuration and bathymetry.
Orbital parameters as modern
CO2 = 400ppmv.
PRISM orography, ice-sheets, and vegetation:
ΔTglobal = 3.1oC
![Page 14: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/14.jpg)
400ppmv to 280ppmv…
Changes to the model for each hypothesis tested…
![Page 15: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/15.jpg)
Panama ENSO Rockies CO2
Temp
Precip
GCM results…
![Page 16: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/16.jpg)
Ice sheet model results…
Lunt et al, Nature, 2008
![Page 17: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/17.jpg)
But…
”Never trust a single model simulation”
Stone et al, The Cryosphere, in press
![Page 18: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/18.jpg)
![Page 19: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/19.jpg)
So, what is robust?
21% of simulations show ‘large’ (>3 m) change due to CO2
18% of simulations show ‘small’ (<0.2 m) change due to CO2
100% of simulations show a greater change due to CO2
than any other mechanism.
![Page 20: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/20.jpg)
DeConto et al, Nature, 2008
![Page 21: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/21.jpg)
Vizcaino et al, Palaeoceanography, 2010
![Page 22: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/22.jpg)
Foster et al, Climate of the Past, in press
Possible role for Canadian Rockies uplift?
![Page 23: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/23.jpg)
Possible “Priming” mechanism for Cordilleran ice sheet.
And possible explanation for non-glaciation in the low CO2 of the Miocene:
![Page 24: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/24.jpg)
Summary
Enhancement of Greenland glaciation around 2.75 Ma
Many hypotheses including CO2, Panama, Rockies, ENSO …
Modelling work indicates CO2 is primary driver, with orbital modulation. BUT, magnitude of effect is uncertain.
Maybe role for Canadian Rockies uplift in determining timing of more general NH glaciation…..and non-glaciation during low CO2 time periods
![Page 25: Pliocene Climate Modelling, and the onset of Northern Hemisphere Glaciation 1)The Pliocene 2)Expansion of Greenland glaciation in the Late Pliocene – uncertainties.](https://reader036.fdocuments.net/reader036/viewer/2022062511/5515e32e55034638038b4cfe/html5/thumbnails/25.jpg)
Problems / Challenges for pre-Quaternary ice sheets and climate…
pre ice-core multiproxy CO2 reconstructions
Interpretation of records – proxy modelling
Development and use of Earth System Models – especially with fully coupled ice sheets
Proper treatment of uncertainties in modelling
Can pre-quaternary data ever constrain ice sheet models?