Global Glacier and Ice Cap contributions to Sea Level Rise
This presentation is the property of its rightful owner.
Sponsored Links
1 / 33

INSTAAR Univ. of Colorado PowerPoint PPT Presentation


  • 60 Views
  • Uploaded on
  • Presentation posted in: General

Global Glacier and Ice Cap contributions to Sea Level Rise W.T. Pfeffer*, INSTAAR/University of Colorado. Calving and subglacial flood, Columbia Glacier, Alaska, 2004. W.T. Pfeffer. *with contributions from AMAP/SWIPA Glacier and Ice Cap working group, Mark Dyurgerov, Mark Meier.

Download Presentation

INSTAAR Univ. of Colorado

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Instaar univ of colorado

Global Glacier and Ice Cap contributions to Sea Level RiseW.T. Pfeffer*, INSTAAR/University of Colorado

Calving and subglacial flood, Columbia Glacier, Alaska, 2004

W.T. Pfeffer

*with contributions from AMAP/SWIPA Glacier and Ice Cap working group,

Mark Dyurgerov, Mark Meier

INSTAAR Univ. of Colorado


Components of sea level rise slr relative contributions

  • Steric (thermal expansion)

    • Upper ocean (top 700 m)

    • Lower ocean)

  • Eustatic (new water)

    • Antarctica

    • Greenland

    • Glaciers and Ice Caps (GIC)

    • Terrestrial storage

      • Ground water

      • Surface water

        • a. Reservoir storage

  • 3. Relative (local)

  • a. Dynamics (winds/currents)

  • b. Gravitational

  • c. Isostatic rebound

  • d. Coastal subsidence

  • 1. Infrastructure loading

  • 2. SLR loading

  • 3. Upstream sediment trapping

  • 4. Groundwater depletion

fromDomingues et al, Nature 2008

Components of Sea Level Rise (SLR) - Relative Contributions

Objective: Assess current eustatic SLE contributions from all sources with meaningful uncertainties, and forecast future SLE on useful time scales (decades-century) with meaningful uncertainties.

INSTAAR Univ. of Colorado


Glacier and ice cap regions from radic and hock in press

Current work:

SWIPA glacier and ice cap module (AMAP)

Radic and Hock (in press) improved estimates of global GIC volume.

and others…

Glacier and Ice Cap regions (from Radic and Hock in press)

INSTAAR Univ. of Colorado


Glacier and ice cap global area is poorly constrained

Glacier and Ice Cap global area is poorly constrained:

Earlier evaluations did not consider GIC surrounding Greenland and Antarctica

SLE (m)

0.50

0.72

from Dyurgerov and Meier, 2005

Global GIC volume “known” to within ~22 cm SLE

INSTAAR Univ. of Colorado


Glacier and ice cap volume summary current 2009

Glacier and Ice Cap volume summary (current 2009)

factor 1/k adjusts for missing data

Glacier and Ice Cap regional volumes (from Radic and Hock in press)

INSTAAR Univ. of Colorado


Glacier and ice cap mass loss summary current 2009

Data (area) sources:

Inventoried regions:

WGI-XF

Greenland: Weng (1995) >

de Woul (2008)

Antarctica*: Shumski (1969),

Dyurgerov and Meier (2005),

Hock et al (2009)

Other uninventoried regions:

GGHYDRO 2.3 (Cogley, 2003)

Glacier and Ice Cap mass loss summary (current 2009)

*Antarctic total : 169 x 103 km2

(Shumski, 1969)

Mainland only: 132 x 103 km2

(Hock et al, 2009)

Ant. Peninsula only: 116 x 103 km2

(Rignot et al 2008)

Glacier and Ice Cap regions (from Radic and Hock in press)

INSTAAR Univ. of Colorado


Wgi xf data set biased toward small land terminating glaciers

e.g. WGI-XF missing Bering Glacier, Alaska

Devon Ice Cap, Canada

Flade Isblink, Greenland

Generally, observations missing in Greenland, Antarctica, USA:

WGI-XF Data set: biased toward small land-terminating glaciers

unmeasured

not analyzed

unmeasured

unmeasured

>> Major uncertainties in most basic inventory items:

e.g. area, volume

>> Nearly complete lack of knowledge of properties needed for modeling e.g. topography, velocities, bed topography, size/location of outlets, etc

INSTAAR Univ. of Colorado


Global mass balance of gic no new comprehensive assessment since dyurgerov and meier 2005

Global mass balance of GIC: No new comprehensive assessment since Dyurgerov and Meier, 2005*

Global assessment

relies on records from ca. 300 glaciers out of ~400,000 total.

Number of monitored glaciers is declining.

From data compilation of Dyurgerov and Meier, 2005

*but see Dyurgerov, “Reanalysis of Glacier Changes Between the IGY and IPY, 1960-2008)” in prep.

INSTAAR Univ. of Colorado


Glacier and ice cap mass loss summary global current 2005

Glacier and Ice Cap mass loss summary Global (current 2005)

402± 95 GT/yr in 2006

INSTAAR Univ. of Colorado


Glacier and ice cap mass loss summary for arctic only current 2009

Glacier and Ice Cap mass loss summary for Arctic only (current 2009)

INSTAAR Univ. of Colorado


Glacier and ice cap mass loss summary current 20091

Glacier and Ice Cap mass loss summary (current 2009)

SWIPA 5C in Review

INSTAAR Univ. of Colorado


Grace gravity from peltier 2009 showing greenland and alaska mass loss rates corrected for isostacy

GRACE gravity from Peltier, 2009 showing Greenland and Alaska mass loss rates, corrected for isostacy.

INSTAAR Univ. of Colorado


Instaar univ of colorado

Other recent developments:Antarctic Glaciers and Ice Caps SLE contribution 1961-2004 = 0.79 ± 0.34 mm/yr (Hock et al, 2009)Global GIC committed future SLE contribution ~ 0.18 m even with further climate change (Bahr et al, 2009)Calving flux from GIS very poorly known but is ~30-40% of total mass loss where observed (Svalbard, Russian Arctic)

INSTAAR Univ. of Colorado


Instaar univ of colorado

UPDATE: 379 ± ~38 GT/yr (1993-2006)

Dyurgerov, “Reanalysis of Glacier Changes Between the IGY and IPY, 1960-2008)” in prep.

Glaciers and Ice Caps: No comprehensive summation* since Meier et al (2007):-402 ± 95 GT/yr (for 2006)Newer observations (2008) for Alaska show ca. 80-110 GT/yr

402 ± 95 GT/yr (2006)

INSTAAR Univ. of Colorado


Individual ice eustatic components greenland mass loss summary current 2009

Individual Ice/Eustatic Components:Greenland mass loss summary (current 2009)

INSTAAR Univ. of Colorado


Individual ice eustatic components antarctica mass loss summary current 2009

Individual Ice/Eustatic Components: Antarctica mass loss summary (current 2009)

INSTAAR Univ. of Colorado


Relative contributions current 2009

Relative contributions (current 2009)

GIC: 402±95 GT/yr 46%

Greenland: 267±38 GT/yr 31 %

Antarctica: 196±30 GT/yr 23 %

TOTAL: 865 GT/yr

= 2.4 mm/yr SLR

% SLR updated

previous total was

645 GT/yr = 1.8 mm/yr

(Meier et al 2007)

from Meier et al 2007 with updates from Rignot (2008 a,b) and others

(*Dyurgerov in prep result)

INSTAAR Univ. of Colorado


Instaar univ of colorado

The future: Projection of SLR rates forward to 2100 by extrapolation of present-day rates(assuming mass balance acceleration remains constant)

14 GT/yr2

INSTAAR Univ. of Colorado


Instaar univ of colorado

Projection of SLR rates forward to 2100 by extrapolation of present-day (last ca. 5 years) forward with dynamics

Projected contributions

to 2100:

Greenland .44 m 41% (V)

Antarctica .38 m 36% (V)

GIC .25 m 25% (M)

TOTAL 1.06 m

Projected dynamics (Pfeffer et al 2008):

Eustatic: ~ 0.52 to 1.71 m with dynamic projection

Total SLR w/ nominal 0.30 m steric component:

~0.82 to 2.01 m by 2100

INSTAAR Univ. of Colorado


Instaar univ of colorado

Projection of SLR rates forward to 2100 by extrapolation of present-day (last ca. 5 years) forward with dynamics

Examine range of mass balance acceleration:

Greenland -30 ± 11 GT/y2

Antarctica -26 ± 14 GT/y2

GIC -12 ± 6 GT/y2

0.55 m SLE

Gld.

0.41 m SLE

Ant.

0.28 m SLE

GIC

Using Velicogna 2009 values for Greenland and Antarctica,

Meier et al 2007 values for GIC

0.14 m SLE

INSTAAR Univ. of Colorado


Instaar univ of colorado

One complication: West AntarcticaLoss of Ross and/or Filchner-Ronne ice shelves is not imminent, but possible in next century, by submarine melt.Forecast including dynamic response changes in this case.But see recent work by Powell et al on timing of Pliocene W. Ant. collapse

INSTAAR Univ. of Colorado


Instaar univ of colorado

Summary:Present day SLE contributions, next-century projected contributions, and uncertainties for Greenland, Antarctica, and GIC are all ~comparable and significant.GIC observational record is improving in some respects (e.g. GRACE, small-scale airborne altimetry) but at risk of being extinguished in other respects (e.g. mass balance components, velocities

INSTAAR Univ. of Colorado


Instaar univ of colorado

Recommendations for GIC:1. Complete GLIMS inventory, continue/expand GIC mass balance measurement programs. 2. NEED DATA TO GO INTO GLIMS: Glacier outlines esp. in Antarctica and Patagonia.3. Update/revamp WGI to include full range of GIC. Significant data missing from Antarctica, North America, Russian Arctic, Patagonia and High Asian Arctic4. Remote sensing data needed: Altimetry, InSAR: location/speed of outlets, Airborne/shipborne soundings: bathymetry in front of outlets, depth sounding in outlets, microwave observations: snow facies, etc.5. Groundtruth: Velocity, mass balance observations.

INSTAAR Univ. of Colorado


Instaar univ of colorado

Illulissat, Greenland, 2007 W.T. Pfeffer

INSTAAR Univ. of Colorado


Instaar univ of colorado

Over-prediction of future sea level rise may be as expensive as under-prediction:1. For very large SLR predictions, planners start applying triage: Which 20% will be saved, and which 80% will be sacrificed?2. Strong tendency to devalue land placed on seaward side of limit of inundation. Incentive for long-term investment falls without positive defensive action, but forecast will likely come first.

Over-prediction of future sea level rise may more expensive than under-prediction.

INSTAAR Univ. of Colorado


Instaar univ of colorado

INSTAAR Univ. of Colorado


Instaar univ of colorado

Projection of net SLR forward to 2100 by extrapolation of present-day (last ca. 5-10 years) forward without dynamics

2100

Sea level equivalent (m)

Sea level equivalent (m)

0.41 m SLE

No Dynamic Projection – this is strictly empirical projection of observed present-day rates forward to 2100

INSTAAR Univ. of Colorado


Instaar univ of colorado

Projection of SLR rates forward to 2100 by extrapolation of present-day (last ca. 5 years) forward with dynamics

Estimated SLR to 2100 with dynamics using Pfeffer et al 2008, high- and low-range estimates.

Dynamic response applies to allcategories: GIC, Greenland, and Antarctica

INSTAAR Univ. of Colorado


Components of sea level rise slr relative contributions1

Components of Sea Level Rise (SLR) - Relative Contributions

Significant uncertainties apply to all components

INSTAAR Univ. of Colorado


Urgency of response varies with rate of environmental change

Urgency of response varies with rate of environmental change

What are rates A & B?

Rate A may be ~20th C rate;

B much harder to estimate

A B

INSTAAR Univ. of Colorado


Cost of uncertainty value of reducing uncertainty varies over time

Cost of uncertainty (value of reducing uncertainty) varies over time

What are time scales C and D?

C: Possibly ~ 1 year (reducing uncertainty in sea level forecast on much shorter time scales isn’t useful).

D: Possibly 50-100 years (reducing uncertainty in sea level forecast 500 years from now isn’t politically/economically usable).

Long-term determinations not useful in the absence of medium-short term determinations

INSTAAR Univ. of Colorado


Uncertainty in predictions of future ice sheet and glacier ice cap response

Uncertainty in predictions of future Ice Sheet and Glacier/Ice Cap response

GIC rate uncertainty is initially greater than Greenland or Antarctic rate uncertainty, but will become less at some point in the future (> 50 years) as GIC volume diminishes.

INSTAAR Univ. of Colorado


Uncertainty in predictions of future ice sheet and glacier ice cap response1

Uncertainty in predictions of future Ice Sheet and Glacier/Ice Cap response

GIC net contribution will be surpassed by Greenland and Antarctic contribution at some point in the future (> 50 years) as GIC volume and loss rate diminishes.

But all magnitudes are significant within the century time scale.

INSTAAR Univ. of Colorado


  • Login