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Atmos-Driven Collapse (Larsen B Collapse 2002 (Possible cause:…
Atmos-Driven Collapse
Larsen B Collapse
2002
Possible
cause:
Hydrofracture - melt forced open crecasses
--> as ice shelf depressed under weight of melt
When lakes drain
-
ice shelf bent & weakened
(elastic def)
Could eventually break into lotsa small icebergs i.e. with tidal bending
Melt ponded on surface
Ice shelf disintegrated in 3 months
Lake effect
Leaves ice shelf with lotsa cracks ∴ little structural integrity
∴ Small perturbation can cause obliteration i.e. tidal flexure
Lakes formation requires snow/firn = deluged with surface melt
Larsen B may be warm enough for lake
Far enough North ?
Fohn wind
warm, dry from Peninsula Mtns
Forms in lee of mtns after orographic rains
More effective @ ice shelf removal
vs ocean melting
Larsen C Collapse
2017
Calved in 2017 as got too long
i.e. moved to a point where unconfined
∴ couldn't extend much further
Absence of ocean melting to control length ∴ calved
No melt ponds seen yet
Implications Larsen B Collapse
Glaciers previously buttressed by Larsen B
= sped up threefold soon after
Scambos 2004
These glaciers shallow inland (mtn range)
∴ little RSL contribution
Most ocean termini in Greenland
= tidewater glaciers
terminate at ice cliffs
Jakobshavn Isbrae
Joughin et al 2002
Jakobshavn Isbrae, W Greenland
Disintegration 20km long ice tongue
in a decade (late 1990s)
Provided buttressing to glacier?
--> glacier sits in deep trough
Glacier velocities doubled after losing tongue
from 8 to 13 km/yr (now faster still)
Cause = Unknown - poor satellite imagery