The calving rates and calving styles of temperate glaciers that calve into fresh water are distinctively different from those of temperate tide-water glaciers. These contrasts are important for interpreting and predicting the response of ice masses to climate change. Glaciar Upsala is a large calving outlet of Hielo Patagónico Sur (southern Patagonia ice field). Its twentieth-century retreat has been climate-driven but significantly modulated by calving dynamics and by the transition from melting to calving at its eastern terminus. Here, the onset of rapid calving in the early 1980s initiated retreat at ≤440 m a−1. The 1992–93 calving rate (vc) is estimated to be 60 m a−1 in a mean water depth (hw) of 67 m. A vc/hw relationship for fresh water based on 14 sites around the world, including seven deep-water sites, confirms both the linear dependency of vc on hw and the contrast between calving rates in tide water and fresh water. As yet, no physical explanation for this contrast exists, but differences in subaqueous melt rates, longitudinal strain rates and crevassing may provide a partial explanation.
Ellglish .\ ·alure .. \ ·orllullillsler HOllse, Pelerborough PE/ /C.-1. EI/glalld ABSTR ACT. Th e ca h-ing ra tes a nd ea h-ing sty les o f" tcmperat e g lac iers th a t ca h-e into fr es h wa te r a re distin e ti\T ly difTerent fro m th ose o f tempera te tid e-wa ter g lac iers. Th ese co ntras ts a rc impo rta nt fo r interpre ting a nd predi c ting th e res po nse 0 [" ice m asses to clim a te ch a nge. Gl acia l' Cpsa la is a la rge ea h-ing o utl et of Hiel o Pa tago ni co Sur (so uth ern Pa tago nia ice fi eld ). Its t\l'enti eth -ce ntury retrea t h as bee n c1im a tc-dri\'en but sig nifi cantl y m odul a ted by ca king dyn a mi cs a nd b y th e tra nsiti on fi'o m mclting to ca king at it s eas tern term inus. H ere. th e o nse t of ra pid ca king in th c ea rly 1980s initi a ted retreat a t ::;4+0 m a I . Th c 1992 93 cah-in g ra te (oe) is es tim a ted to I)e 60 m Cl 1 in a m ean wa ter d epth (h\\") 0(" 67 m. A ve/ h\\" rela ti onship fo r [iTs h \I'ater based 0 11 14 sites a ro und th e \I·o rld . including se\'e n d ee p-\l'atcr sites, confirms bo th th e lin ea r d epend enn ' of lie o n h\\" a nd th c eonrras t bet\\Te n ca h-in g ra tes in tid e \\'a ter a nd fi'esh \\·Llt e r. As \ ·C l. no ph ys ica l expl a na tion fo r this contras t cxi sts, but differenccs in sub aqu co us m elt ra tes, lo ng itudin a l stra in rates a nd cre\'a ssin g m ay prO\'id e a partia l expl a n a tion. CAL VING RATES IN FRESH WATERC a h-in g rem a in s on e o f th e leas t und erstood g lae io logica l processes . C a kin g g laci ers arc se nsiti\'e to tro ug h geom e tr y, a nd b eca use o f the in sta bi li ty of ca king termini th ey ca n n ue ru a te independ e n th-o f clim a te ( :\ I eier a nd Pos t. 198 7: \\·a n·e n. 1991. 1992 ). Ca h 'in g ra tes co rrela te stro ng lv with bo th \\'a ter depth a nd ice thi ckn ess a t th e te rmin us (Brown a nd others, 1982 ) , bu t th e ph ys ica l n a ture o f th ese re la ti o nships remains unc lea r (Hu g h es , 1992; :\l eier. 1994 ). T empe ra te tid e-\\'a ter g laciers h a \'e b ee n extcnsi\'C ly stud ied , \\·he reas fres h-\\'a ter cakin g g lac ie rs ha \'e rece i \'ed li ttle a lte n ti o n d es pi te th e sig n i [~ ica nee of {i'Cs h-wa te r cah'in g fo r g lacio-climati e re la tionships tod a y a nd in geo logica l tim e (Kirkbrid e , 199 3 ; W a rre n , 199+) . I nt e r es t in fr es h-\\'a te r ca kin g \\'as stimul a ted b y h ydro-p ower sc hC'm es in g la ci e ri zed ca tc hm ents L a um a nn a nd \\'old , 1992 ). Such studi es rn'ea lcd th a t, in a n y g ivc n wa ter depth (hw), ca h-ing ra tes (vc) are a bo ut a n o rd er o f" m ag nitud e less th a n those in tid e wa ter Th e necd fo r a n impro \'Cd d a ta base of IITs h-\\'a ter ca h 'ing ra tes pro mpted thi s wo rk in Pa tago ni a . Th e m aj o r eas tern o utle t g lacie rs o f Hi cl o P a tago n ico Sur (south e rn Patago nia ice field ) a ll cake into la rge, d ee p la kes (\\'a rre n a nd Sugd e n , 1993 ) . In thi s stud y o f th e hi stori c \)eh a \'io ur of Gl ac ia r U psa...
The stillstand positions of many tidewater glaciers in Scottish sea lochs during the Loch Lomond Stadial correspond closely with topographic pinning points in the lochs. These pinning points are locations where the fjord geometry changes significantly, allowing the ablation rates of calving glaciers to alter and restore dynamic equilibrium. Evidence also suggests that water depth may have influenced rates of advance and retreat. Following an initial climatic trigger, the subsequent behaviour of these tidewater glaciers may therefore reflect the influence of trough geometry. The response of calving glaciers to further small-scale climatic changes can be indirect and variable. This behaviour is analogous to that of contemporary Alaskan tidewater glaciers.
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