Long- -Term Changes in Global Term Changes in Global Long Sea - - PowerPoint PPT Presentation

▶
long term changes in global term changes in global long
SMART_READER_LITE
LIVE PREVIEW

Long- -Term Changes in Global Term Changes in Global Long Sea - - PowerPoint PPT Presentation

Nov 29, 2023 38 likes •110 views

Public Policy Forum Public Policy Forum 10 March 2010 10 March 2010 Long- -Term Changes in Global Term Changes in Global Long Sea Level Sea Level Craig S. Fulthorpe Craig S. Fulthorpe University of Texas Institute for Geophysics

slide-1
SLIDE 1

Public Policy Forum Public Policy Forum

10 March 2010 10 March 2010

Long Long-

  • Term Changes in Global

Term Changes in Global Sea Level Sea Level

Craig S. Fulthorpe Craig S. Fulthorpe

University of Texas Institute for Geophysics University of Texas Institute for Geophysics John A. and Katherine G. Jackson School of Geosciences John A. and Katherine G. Jackson School of Geosciences

slide-2
SLIDE 2

Causes and Effects of Global Sea Causes and Effects of Global Sea-

  • Level Change

Level Change

Growth and decay of continental ice Growth and decay of continental ice sheets has been the primary cause of sheets has been the primary cause of large sea large sea-

  • level changes (e.g., ~120 m

level changes (e.g., ~120 m lower at last glacial maximum) for at lower at last glacial maximum) for at least the last 40 million years least the last 40 million years

Miller et al. (2005)

Total potential sea Total potential sea-

  • level rise cause by

level rise cause by melting of onshore ice sheets is ~70 m. melting of onshore ice sheets is ~70 m.

  • All of Antarctica: ~57

All of Antarctica: ~57-

  • 60 m (IPCC)

60 m (IPCC)

  • West Antarctic Ice Sheet

West Antarctic Ice Sheet alone: up to ~7 m alone: up to ~7 m

  • Greenland: ~7 m

Greenland: ~7 m Principal methods for estimating long Principal methods for estimating long-

  • term changes in sea

term changes in sea-

  • level:

level: 1) 1) Oxygen isotopic record from deep Oxygen isotopic record from deep-

  • sea sediments

sea sediments 2) 2) Continental margin sedimentary sequences Continental margin sedimentary sequences

slide-3
SLIDE 3
  • 1. Oxygen Isotopic Record of Ice Volume and Temperature
  • 1. Oxygen Isotopic Record of Ice Volume and Temperature
  • DSDP/ODP/IODP drilling of pelagic sediments

DSDP/ODP/IODP drilling of pelagic sediments has revolutionized climate studies by providing has revolutionized climate studies by providing long long-

  • term oxygen isotopic records.

Record from >40 scientific ocean drilling sites Record from >40 scientific ocean drilling sites ( (Zachos Zachos et al., 2001) et al., 2001)

term oxygen isotopic records.

  • High

High-

  • frequency (40

frequency (40 ky ky – – 100 100 ky ky), ), orbitally

  • rbitally forced

forced climate change is modulated by long climate change is modulated by long-

  • term

term changes in plate motion, oceanic gateways and changes in plate motion, oceanic gateways and atmospheric CO atmospheric CO2

2.

. Abrupt Events Abrupt Events

  • PETM (55 Ma): 5

PETM (55 Ma): 5-

  • 6

6° °C rise in deep C rise in deep-

  • sea

sea temperature in <10 temperature in <10 ky ky (release of methane from (release of methane from marine gas hydrates?) marine gas hydrates?)

  • Cooling events: Oi

Cooling events: Oi-

  • 1 (34 Ma), Mi

1 (34 Ma), Mi-

  • 1 (23 Ma)

1 (23 Ma)

Climate, and sea level, do not always Climate, and sea level, do not always respond linearly to forcing respond linearly to forcing

slide-4
SLIDE 4

Early Pliocene Warm Period Early Pliocene Warm Period

Schweitzer and Thompson (1996); USGS Open Schweitzer and Thompson (1996); USGS Open-

  • File Report 96

File Report 96-

  • 000

000

  • No Northern Hemisphere

No Northern Hemisphere ice, periodic (40 ice, periodic (40 ky ky) collapse ) collapse

  • f West Antarctic Ice Sheet.
  • f West Antarctic Ice Sheet.
  • 7

7-

  • 10 m sea

10 m sea-

  • level

level equivalent. equivalent.

  • CO

CO2

2 similar to present, but:

similar to present, but:

  • ~3

~3° °C warmer (IPCC C warmer (IPCC estimate this would estimate this would require a doubling of require a doubling of CO CO2

2)

)

  • Sea level ~25 m higher.

Sea level ~25 m higher.

  • So climate and sea level

So climate and sea level were more sensitive to CO were more sensitive to CO2

2

variation than today. variation than today.

  • Provides a glimpse of the

Provides a glimpse of the future Earth system.

After After Lisiecki Lisiecki and and Raymo Raymo (2005). Figure by R. Rohde, Global Warming Art project. (2005). Figure by R. Rohde, Global Warming Art project.

future Earth system.

slide-5
SLIDE 5
  • 2. Estimating Sea
  • 2. Estimating Sea-
  • Level Change Using

Level Change Using Continental Margin Drilling Transects Continental Margin Drilling Transects

  • Targets the environment directly affected by sea

Targets the environment directly affected by sea-

  • level change

level change

Expedition 317: Expedition 317: Canterbury Basin, Canterbury Basin, New Zealand New Zealand

  • Thick early

Thick early Pliocene section Pliocene section

slide-6
SLIDE 6

Climatic and Global Sea Climatic and Global Sea-

  • Level Records

Level Records

Stratigraphic Stratigraphic signature of the signature of the Neogene Neogene ( (Bartek Bartek et al., 1991)

Figure by A. Figure by A. Droxler Droxler, , Rice University Rice University

et al., 1991)

1) Late Oligocene 1) Late Oligocene-

  • early Miocene aggradation, backstepping and partial drowning

early Miocene aggradation, backstepping and partial drowning 2) Late early Miocene 2) Late early Miocene-

  • early middle Miocene vertical growth or aggradation

early middle Miocene vertical growth or aggradation 3) Earliest middle Miocene downward shift of deposition 3) Earliest middle Miocene downward shift of deposition 4) Late middle Miocene systematic lateral growth (progradation) 4) Late middle Miocene systematic lateral growth (progradation) 5) Late Miocene 5) Late Miocene-

  • early Pliocene re

early Pliocene re-

  • flooding and aggradation

flooding and aggradation

slide-7
SLIDE 7

Importance of Studying Past Sea Importance of Studying Past Sea-

  • Level Change

Level Change

  • The geologic record provides an opportunity to quantify the tim

The geologic record provides an opportunity to quantify the timing, amplitudes, ing, amplitudes, rates, mechanisms/controls, and effects of global sea rates, mechanisms/controls, and effects of global sea-

  • level change.

level change.

  • This record can tell us:

This record can tell us:

  • How the earth system has operated during past abrupt climate ch

How the earth system has operated during past abrupt climate changes and anges and under past conditions of extreme climate forcing. under past conditions of extreme climate forcing.

  • The potential sea

The potential sea-

  • level response (rates and amplitudes) to elevated CO

level response (rates and amplitudes) to elevated CO2

2

levels. levels.

  • Improved understanding of the long

Improved understanding of the long-

  • term record of global sea

term record of global sea-

  • level change:

level change:

  • Enables critical evaluation of computer model predictions.

Enables critical evaluation of computer model predictions.

  • Improves our ability to predict the societal impact of future s

Improves our ability to predict the societal impact of future sea ea-

  • level change

level change and allow us to better assess the contribution of greenhouse gas and allow us to better assess the contribution of greenhouse gases. es. craig@ig.utexas.edu craig@ig.utexas.edu www.ig.utexas.edu www.ig.utexas.edu