the state of kersten glacier and the northern icefield on mt. kilimanjaro · 2020. 4. 30. ·...

C. Stadelmann, J.J. Fürst, T. Seehaus, P. Sirguey, N. Cullen, T. Mölg and M. Braun

Introduction: Glaciers on KilimanjaroThe glaciers on Kilimanjaro are unique indicators for climatic changes in the tropical

mid-troposphere of Africa. Glaciers in the tropics have shown a severe retreat since

the Last Glacial Maximum and the glaciers on Mt. Kilimanjaro are no exception, with

an 85% reduction in glacier area from 1912 to 2013. This history of severe glacier area

loss raises concerns about an imminent future disappearance. Yet, the remaining ice

volume is not well known.

On this poster, we present well constrained thickness maps for the two largest

remaining ice bodies on Mt. Kilimanjaro and a first estimate of their state in 2049.

Results: Ice thickness maps for 2000 and 2011

Discussion and Implications: The future ofKilimanjaro's glaciers

TanDEM-X

height change

SRTM DEM

glacier

outlines

thickness

observations

KILISoSDEM

margin

thicknesses

(Bohleber et al. 2017)

(Sirguey & Cullen 2013)

Data and Methods:From input data to ice thickness map

Projection for 2049:

Climatic conditions were inferred

from climate model anomalies

(GISS-E2-H; RCP4.5) added to

the AWS (temp., precip., etc.)

This future projection must be

assessed with care as horizontal

cliff retreat was not considered.

Cliff retreat evidently plays a

significant role in the evolution of

glaciers on Mt. Kilimanjaro (Mölg

& Hardy 2004) with lateral

retreat reaching 13 cm/month

(Winkler et al. 2010).

Ice thickness (m)<= 2.5

2.5 - 5

5 - 7.5

7.5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

30 - 40

> 40

Area Change2000-2011Glacier Extent 2011

96590009660000

96610009662000

316000 317000

Correspondence/Contact: Catrin Stadelmann, catrin.stadelmann@fau.de

globe with east africa

GPR measurements(Bohleber et al. 2017)Study SitesRGI6.0 Outlines

Basemap (c) KILISoSDEM(Sirguey et al. 2013)

96590009660000

96610009662000

315000 316000 317000 318000 319000

∂H / ∂t + ∇ · (uH) = ḃ s + ḃ b

Ice thickness reconstruction approach

Based on the principle of mass conservation

Flux solution is converted to thickness values

using the Shallow Ice Approximation

Nominal mesh resolution of 25m and 2m for

the states in 2000 and 2011, respectively

2049

2011

Future Projection on glacier recession

GCM dataGISS-E2-H r3i1p1 model setup using the

RCP4.5 scenario

Adjusting AWS data with GCM calculated

differences (2005-2013 to 2040-2049)

96590009660000

96610009662000

B

96590009660000

96610009662000

UTM

Y-coordinate (m)

C

UTM

Y-coordinate (m)

UTM

Y-coordinate (m)

UTM X-coordinate (m)

A

D

Figure 1: Results of the ice thickness reconstruction for the years 2000 (A, B),

2011 (D). (C) is the result of the global consensus estimate by Farinotti et al.

(2019) for the 2000 glacier state. (A) uses margin thickness information, (B, D)

use the mean glacierwide viscosity instead of thickness observations for

Kersten Glacier. On the Northern Icefield, thickness measurements from

Bohleber et al. (2017) were available.

Ice thickness 2011 - SMBGCM

2000

Bohleber, P., et al., The Cryosphere, 11, 469–482, doi: 10.5194/tc-11-469-2017, 2017.Fürst, J. J., et al., The Cryosphere, 11, 2003–2032, doi: 10.5194/tc-11-2003-2017, 2017.Mölg, T. and Hardy, D.R., J. Geophys. Res., 109, D16104, doi: 10.1029/2003JD004338, 2004. Mölg, T., et al., J. Clim., 22, 4162–4181, doi: 10.1175/2009JCLI2954.1, 2009a.Sirguey, P. and Cullen, N. J., Survey Quarterly, 76, 5–7, 2013.Winkler, et al. (2010), Erdkunde 64 (2), 179–193. doi: 10.3112/erdkunde.2010.02.05.

AWS data

Margin thickness generation

The state of Kersten Glacier and the Northern Icefield on Mt. Kilimanjaro

(Fürst et al. 2017)

Mean annual SMB

(Mölg et al. 2009)

Results from our locally tuned reconstruction match estimates

from other studies (Bohleber et al. 2017, Farinotti et al. 2019)

Margin thickness information can be used to create an ice

thickness estimate without actual thickness observations

Our future projection shows an already severe glacier retreat

without the consideration of the lateral cliff retreat

Surface height change(m/yr)

< = -1.5

-1

-0.5

0

> 0

- =

2000 (RGI) 2011

Fig. 2: Ice thickness field in 2049; cumulated

annual surfaces mass balance were subtracted

from the 2011 ice thickness (Fig. 1 D).

Outline difference

96590009660000

96610009662000

316000 317000

Surface Height Change(m yr⁻ ¹)

< = -1.5

-1

-0.5

0

> 0

UTM

Y-coordinate (m)

UTM X-coordinate (m)

9659

000

9660

000

9661

000

9662

000

316000 317000Surface Mass Balance(kg m⁻ ² a⁻ ¹)

= < -800

-600

-400

-200

0

> 0

UTM

Y-c

oord

inat

e (m

)

UTM X-coordinate (m)

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