Cumulative mean According to climate scenarios for the end of the 21st
annual ice loss
century, changes in global temperature and precipitation
(mm w.e.)
range between +1.1 to +6.4 °C and –30 to +30 per cent, re-
0
spectively
1
. Such an increase in mean air temperature will
-2 000 continue the already dramatic glacier changes. Cold con-
tinental-type glaciers will react in the first instance with
-4 000
a warming of the ice and firn temperatures, whereas gla-
-6 000
ciers with ice temperatures at the melting point will have
to convert the additional energy directly into melting
7,8
.
-8 000
-10 000 Low-latitude mountain chains like the European Alps or
1975 1980 1985 1990 1995 2000 2005
the Southern Alps of New Zealand, where glaciers are
typically medium-sized and found in quite steep moun-
tains, will experience rapid glacier changes in adaptation
to the modified climate. A modelling study shows that
the European Alps would lose about 80 per cent of their
glacier cover should summer air temperatures rise by
3°C, and that a precipitation increase of 25 per cent for
each 1°C would be needed to offset the glacial loss
19
.
In heavily glacier-covered regions like Patagonia (Argenti-
na, Chile) or the St. Elias Mountains (Alaska), the landscape
is dominated by relatively few large and rather flat valley
glaciers. Because long, flat valley glaciers have dynamic
Figure 6B.6: Mass balance reference glaciers in nine mountain
response times beyond the century scale
10,11
, rapid climate
ranges. The 30 glaciers lost on average more than 9.5 m water
change primarily causes (vertical) thinning of ice rather
equivalent in thickness over the period 1976–2005.
than (horizontal) retreat and area reduction. For such cases,
Source: Data from the World Glacier Monitoring Service, Zurich, Switzerland
conditions far beyond equilibrium stages, perhaps even
run-away effects from positive feedbacks (mass balance/al-
titude), must be envisaged
20,25
. Downwasting or even col-
lapse of large ice bodies could become the most likely future
Outlook for glaciers scenarios related to accelerating atmospheric temperature
rise in these areas, and have already been documented
26,27
.
The total increase of global mean air temperature of
about 0.75 °C since 1850 is clearly manifested in the Under the present climate scenarios
1
, the ongoing trend
shrinking of glaciers and ice caps worldwide
1
. The sensi- of worldwide and fast, if not accelerating, glacier shrink-
tivity of glaciers in humid-maritime areas to this warm- age on the century time scale is of a non-periodical na-
ing trend has been found to be much higher than that of ture and may lead to the deglaciation of large parts of
glaciers in dry-continental areas
7,21
. many mountain regions in the coming decades.
122 GLOBAL OUTLOOK FOR ICE AND SNOW
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169  |  Page 170  |  Page 171  |  Page 172  |  Page 173  |  Page 174  |  Page 175  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192  |  Page 193  |  Page 194  |  Page 195  |  Page 196  |  Page 197  |  Page 198  |  Page 199  |  Page 200  |  Page 201  |  Page 202  |  Page 203  |  Page 204  |  Page 205  |  Page 206  |  Page 207  |  Page 208  |  Page 209  |  Page 210  |  Page 211  |  Page 212  |  Page 213  |  Page 214  |  Page 215  |  Page 216  |  Page 217  |  Page 218  |  Page 219  |  Page 220  |  Page 221  |  Page 222  |  Page 223  |  Page 224  |  Page 225  |  Page 226  |  Page 227  |  Page 228  |  Page 229  |  Page 230  |  Page 231  |  Page 232  |  Page 233  |  Page 234  |  Page 235  |  Page 236  |  Page 237  |  Page 238