Global Outlook for Ice & Snow

New Zealand

Apart from a few glaciers on Mt. Ruapehu volcano in the North Island, the bulk of New Zealand’s glaciers are located in the Southern Alps. They reached their maxi- mum recent extent towards the end of the 18th century, with only minor retreat until the end of the 19th cen- tury 153 . Total glacier area was 1158 km 2 in 1978, with an estimated total ice volume of about 53 cubic km 154,155 . The overall estimated area and volume changes since the mid of the 19 th century are –49 and –61 per cent, respectively 156 . Since the mid-1970s, the glaciers overall have experienced positive mass balances with those hav- ing short response times advancing noticeably from the mid-1980s. This period of advances appeared to be com- ing to an end at the beginning of the new century 157 . A recent study 85 estimates a net ice volume loss over the period 1977–2005 of 17 per cent, mainly due to calving into lakes and associated wasting at glacier tongues. Mass loss due to changes in glacier thickness, excluding that related to lake growth, has contributed only 7 per cent to the overall ice loss since 1977.

in the 20th century, increased temperature became an additional driver, although its relative importance is still debated 147–149 . Over the last century (1906–2006), these gla- ciers have lost an estimated 82 per cent of their area – from approximately 21 to 3.8 km². Close to 50 per cent of the glaciers on the Rwenzori Mountains, Mount Kenya and Kilimanjaro have disappeared, while larger glaciers – par- ticularly on Kilimanjaro – have been fragmented 148,150,151 . The most pronounced impact of these receding glaciers is on the scenery. Unlike mountain glaciers in higher lati- tudes, the shrinking of the East African glaciers will have no significant impact on water resources. The hydrology on these mountains is dominated by extensive forest belts (hundreds to thousands times larger than the glaciated area) with a much higher annual rainfall. If all the glaciers on Kilimanjaro – which has the highest glacier to forest area ratio – were to melt in just one year, the resulting loss in water resources would be equivalent to only four per cent of the total annual rainfall over the forest belt 152 .

CHAPTER 6B

GLACIERS AND ICE CAPS

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