Durham Research Online
Deposited in DRO:
11 June 2013
Version of attached le:
Accepted Version
Peer-review status of attached le:
Peer-reviewed
Citation for published item:
Hanna, E. and Navarro, F.J. and Pattyn, F. and Domingues, C.M. and Fettweis, X. and Ivins, E.R. and
Nicholls, R.J. and Ritz, C. and Smith, B. and Tulaczyk, S. and Whitehouse, P.L. and Zwally, H.J. (2013)
'Ice-sheet mass balance and climate change.', Nature., 498 (7452). pp. 51-59.
Further information on publisher's website:
http://dx.doi.org/10.1038/nature12238
Publisher's copyright statement:
Additional information:
Use policy
The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for
personal research or study, educational, or not-for-prot purposes provided that:
•
a full bibliographic reference is made to the original source
•
a link is made to the metadata record in DRO
•
the full-text is not changed in any way
The full-text must not be sold in any format or medium without the formal permission of the copyright holders.
Please consult the full DRO policy for further details.
Durham University Library, Stockton Road, Durham DH1 3LY, United Kingdom
Tel : +44 (0)191 334 3042 | Fax : +44 (0)191 334 2971
https://dro.dur.ac.uk
1
Ice sheet mass balance and climate change 1
2
MS (review article) commissioned for Nature, 22 April 2013 EH version
3
Edward Hanna
1
, Francisco J. Navarro
2
, Frank Pattyn
3
, Catia M. Domingues
4
, Xavier 4
Fettweis
5
, Erik R. Ivins
6
, Robert J. Nicholls
7
, Catherine Ritz
8
, Ben Smith
9
, Slawek Tulaczyk
10
, 5
Pippa L. Whitehouse
11
, H. Jay Zwally
12
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
1
Department of Geography, University of Sheffield, UK 34
2
Universidad Politécnica de Madrid, Spain 35
3
Laboratoire de Glaciologie, Université Libre de Bruxelles, Belgium 36
4
Antarctic Climate and Ecosystems Cooperative Research Centre, Tasmania, Australia 37
5
Department of Geography, University of Liège, Belgium 38
6
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA 39
7
Engineering and the Environment, University of Southampton, UK 40
8
Laboratoire de Glaciologie et Géophysique de l'Environnement, UJF – Grenoble 1 / CNRS, 41
France 42
9
Polar Science Center, Applied Physics Laboratory, University of Washington, USA 43
10
University of California-Santa Cruz, USA 44
11
Department of Geography, Durham University, UK 45
12
NASA Goddard Space Flight Center, Cryospheric Sciences Laboratory, Greenbelt, USA 46
2
Preface 47
48
Since the 2007 Intergovernmental Panel on Climate Change Fourth Assessment Report 49
(IPCC AR4), both new observations of ice-sheet mass balance and improved computer 50
simulations of ice-sheet response to ongoing climate change have been published. While 51
Greenland is losing mass at an increasing pace, Antarctic loss is likely to be less than some 52
recently-published estimates. It remains unclear whether East Antarctica has been gaining 53
or losing mass over the last twenty years, and uncertainties in mass change for West 54
Antarctica and the Antarctic Peninsula remain large. We highlight the last six years of 55
progress and examine the key problems that remain. 56
57
58
59
60
61
62
63
64
65
66
67
68
69
3
1.0 Introduction 70
71
This review aims to synthesize key advances in monitoring and modelling of ice-sheet mass 72
balance since the IPCC AR4
1
. Mass balance is defined as the net result of mass gains 73
(primarily snow accumulation) and mass losses (primarily melt-water runoff and solid ice 74
dynamical discharge across the grounding line). Surface mass balance (SMB) is the net 75
balance of mass gains and losses at the ice-sheet surface and does not include dynamical 76
mass loss. Efforts to determine ice-sheet mass balance using the three satellite geodetic 77
techniques of altimetry, interferometry, and gravimetry (see Section 2.1) have recently 78
been sharpened by carefully defining common spatial and temporal domains for inter-79
comparison
2
. Here we review the latest mass balance estimates for the Antarctic (AIS) and 80
Greenland (GrIS) ice sheets. New glacial isostatic adjustment (GIA) models, tested and 81
evaluated against Global Positioning System (GPS) data, have recently led to significant 82
downwards revision in GIA, and hence downwards revisions of gravimetric and altimetric 83
satellite estimates of Antarctic mass loss
2
(Box 1). 84
Since IPCC AR4, ice-sheet models are no longer constrained to using overly 85
simplified physics, allowing them to more accurately simulate the important coupling 86
between ice sheets, ice streams and ice shelves. This major advance has been accompanied 87
by improved model representation of the complex interactions of the ice-sheet with its bed, 88
the atmosphere and the ocean. For completeness we also discuss briefly the contributions 89
to sea-level rise (SLR) from other sources, namely glaciers and ice caps, thermal expansion 90
of the oceans and terrestrial water storage changes. Despite recent advances, improved 91
observations and predictions of ice-sheet response to climate change are as urgently 92
4
needed to feed into mitigation and adaptation models of ensuing SLR as they were at the 93
time of the AR4. 94
95
2.0 Recent changes in ice sheet mass balance 96
97
2.1 Comparison of mass balance estimates 98
99
One of the most sought-after but elusive goals in contemporary Earth sciences is to relate 100
the mass-balance state of the great ice sheets to observed SLR. A measure of this state 101
provides an unambiguous quantification of the ice-sheet system response to climate 102
change. Recent mass-change estimates have been derived from three categories of 103
techniques: 104
-Volumetric techniques determine changes in the volume of the ice sheet via 105
measurements of the height of the ice-sheet surface. These are based on radar altimetry
3,4
106
or laser altimetry
5
. 107
-Space gravimetric techniques derive changes in ice-sheet mass via repeated and 108
very accurate measurement of the Earth’s gravity field by the Gravity Recovery and Climate 109
Experiment (GRACE) satellite system
6
. 110
-The mass budget technique compares estimates of the net ice accumulation on the 111
ice sheets with estimates of discharge across the grounding line
7
(Box 2). 112
Each estimate relies on observational data that are unique to its own strategy, and 113
each strategy, therefore, has a unique set of sensitivities to the errors and biases in its data. 114
For example, mass budget
7,8
studies use modelled snowfall fields from atmospheric 115
