Supplementary material to "Insensitivity of mass loss of Icelandic Vatnajökull ice cap to solar geoengineering"

Abstract. Basin-3, the largest outlet basin of the Austfonna ice cap, started to surge in autumn 2012. A maximum velocity of 18.8 m d-1 was found in December 2012 / January 2013. Here we present a time series of area wide velocity fields from synthetic aperture radar (SAR) offset tracking and Global Positioning System (GPS) data in the aftermath of the velocity maximum, extending the previously published data from May 2013 to July 2016. We find that terminus velocity slowed down by ~ 50 % until spring 2014, whereas the upper parts of the basin continued to speed-up and reached their maximum only in summer 2014. Until the date of writing (July 2016), Basin-3 maintained high velocity with maxima between 8.9–11.4 m d-1. Summer speed-ups were superimposed even on the otherwise fast surge motion. The total frontal ablation Af over the period 19 April 2012 to 26 July 2016 was calculated to 22.2 ± 8.1 Gt (5.2 ± 1.9 Gt yr-1) from the ice mass flux qfg = 33.2 ± 11.5 Gt (7.8 ± 2.7 Gt yr-1) and the terminus mass change qt = 11.0 ± 3.4 Gt (2.6 ± 0.8 Gt yr-1). Additional advance of the terminus led to a total sea-level rise equivalent of 31.3 ± 11.2 Gt (7.3 ± 2.6 Gt yr-1). This rate of frontal ablation roughly equals previous estimates of both the calving flux and total mass loss from the entire archipelago, resulting in a doubling of the current ice-mass loss from Svalbard. In vicinity of Basin-3, we also observe a terminus advance and a speed-up of the northern part of Basin-2 starting in autumn 2014, with surface velocity reaching 8.71 m d-1 in August 2015. The related ice mass loss of Basin-2 between 20 June 2015 and 26 July 2016 amounts to 0.8 Gt (min: 0.3 Gt, max: 1.6 Gt). Accounting also for the replacement of ocean water, we find a total sea-level rise equivalent of 1.1 Gt (min: 0.5 Gt, max: 2.1 Gt).

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Supplementary material to "Tropical Pacific Climate Variability under Solar Geoengineering: Impacts on ENSO Extremes"

10.5194/acp-2018-1312-supplement ◽

2019 ◽

Author(s):

Abdul Malik ◽

Peer J. Nowack ◽

Joanna D. Haigh ◽

Long Cao ◽

Luqman Atique ◽

...

Keyword(s):

Climate Variability ◽

Tropical Pacific ◽

Solar Geoengineering ◽

Supplementary Material ◽

Pacific Climate Variability

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Supplementary material to "The climate effects of increasing ocean albedo: An idealized representation of solar geoengineering"

10.5194/acp-2018-340-supplement ◽

2018 ◽

Author(s):

Ben Kravitz ◽

Philip J. Rasch ◽

Hailong Wang ◽

Alan Robock ◽

Corey Gabriel ◽

...

Keyword(s):

Climate Effects ◽

Solar Geoengineering ◽

Supplementary Material

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Accelerated contributions of Canada's Baffin and Bylot Island glaciers to sea level rise over the past half century

The Cryosphere ◽

10.5194/tc-6-1103-2012 ◽

2012 ◽

Vol 6 (5) ◽

pp. 1103-1125 ◽

Cited By ~ 45

Author(s):

A. Gardner ◽

G. Moholdt ◽

A. Arendt ◽

B. Wouters

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Integrated Approach ◽

Mass Change ◽

Total Contribution ◽

Ice Cap ◽

Past Half Century ◽

Digital Elevation ◽

Grace Satellite Gravimetry

Abstract. Canadian Arctic glaciers have recently contributed large volumes of meltwater to the world's oceans. To place recently observed glacier wastage into a historical perspective and to determine the region's longer-term (~50 years) contribution to sea level, we estimate mass and volume changes for the glaciers of Baffin and Bylot Islands using digital elevation models generated from airborne and satellite stereoscopic imagery and elevation postings from repeat airborne and satellite laser altimetry. In addition, we update existing glacier mass change records from GRACE satellite gravimetry to cover the period from 2003 to 2011. Using this integrated approach, we find that the rate of mass loss from the region's glaciers increased from 11.1 ± 3.4 Gt a−1 (271 ± 84 kg m−2 a−1) for the period 1963–2006 to 23.8 ± 6.1 Gt a−1 (581 ± 149 kg m−2 a−1) for the period 2003–2011. The doubling of the rate of mass loss is attributed to higher temperatures in summer with little change in annual precipitation. Through both direct and indirect effects, changes in summer temperatures accounted for 70–98% of the variance in the rate of mass loss, to which the Barnes Ice Cap was found to be 1.7 times more sensitive than either the Penny Ice Cap or the region's glaciers as a whole. This heightened sensitivity is the result of a glacier hypsometry that is skewed to lower elevations, which are shown to have a higher mass change sensitive to temperature compared to glacier surfaces at higher elevations. Between 2003 and 2011 the glaciers of Baffin and Bylot Islands contributed 0.07 ± 0.02 mm a−1 to sea level rise accounting for 16% of the total contribution from glaciers outside of Greenland and Antarctica, a rate much higher than the longer-term average of 0.03 ± 0.01 mm a−1 (1963 to 2006).

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Glacier-surge mechanisms promoted by a hydro-thermodynamic feedback to summer melt

The Cryosphere ◽

10.5194/tc-9-197-2015 ◽

2015 ◽

Vol 9 (1) ◽

pp. 197-215 ◽

Cited By ~ 55

Author(s):

T. Dunse ◽

T. Schellenberger ◽

J. O. Hagen ◽

A. Kääb ◽

T. V. Schuler ◽

...

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Ice Sheets ◽

Glacier Mass Balance ◽

Internal Dynamic ◽

Svalbard Archipelago ◽

Flow Acceleration ◽

Ice Cap ◽

Surface Melt

Abstract. Mass loss from glaciers and ice sheets currently accounts for two-thirds of the observed global sea-level rise and has accelerated since the 1990s, coincident with strong atmospheric warming in the polar regions. Here we present continuous GPS measurements and satellite synthetic-aperture-radar-based velocity maps from Basin-3, the largest drainage basin of the Austfonna ice cap, Svalbard. Our observations demonstrate strong links between surface-melt and multiannual ice-flow acceleration. We identify a hydro-thermodynamic feedback that successively mobilizes stagnant ice regions, initially frozen to their bed, thereby facilitating fast basal motion over an expanding area. By autumn 2012, successive destabilization of the marine terminus escalated in a surge of Basin-3. The resulting iceberg discharge of 4.2±1.6 Gt a−1 over the period April 2012 to May 2013 triples the calving loss from the entire ice cap. With the seawater displacement by the terminus advance accounted for, the related sea-level rise contribution amounts to 7.2±2.6 Gt a−1. This rate matches the annual ice-mass loss from the entire Svalbard archipelago over the period 2003–2008, highlighting the importance of dynamic mass loss for glacier mass balance and sea-level rise. The active role of surface melt, i.e. external forcing, contrasts with previous views of glacier surges as purely internal dynamic instabilities. Given sustained climatic warming and rising significance of surface melt, we propose a potential impact of the hydro-thermodynamic feedback on the future stability of ice-sheet regions, namely at the presence of a cold-based marginal ice plug that restricts fast drainage of inland ice. The possibility of large-scale dynamic instabilities such as the partial disintegration of ice sheets is acknowledged but not quantified in global projections of sea-level rise.

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Long-term contributions of Baffin and Bylot Island Glaciers to sea level rise: an integrated approach using airborne and satellite laser altimetry, stereoscopic imagery and satellite gravimetry

The Cryosphere Discussions ◽

10.5194/tcd-6-1563-2012 ◽

2012 ◽

Vol 6 (2) ◽

pp. 1563-1610 ◽

Cited By ~ 4

Author(s):

A. S. Gardner ◽

G. Moholdt ◽

A. Arendt ◽

B. Wouters

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Integrated Approach ◽

Laser Altimetry ◽

Satellite Gravimetry ◽

Ice Cap ◽

Digital Elevation ◽

Grace Satellite Gravimetry ◽

Summer Temperatures

Abstract. Canadian Arctic glaciers have recently contributed large volumes of meltwater to the world's oceans. To place recently observed glacier wastage into a historical perspective and to determine the region's longer-term (~50 years) contribution to sea level, we estimate mass and volume changes for the glaciers of Baffin and Bylot Islands using Digital Elevation Models generated from airborne and satellite stereoscopic imagery and elevation postings from repeat airborne and satellite laser altimetry. In addition, we update existing glacier mass change records from GRACE satellite gravimetry to cover the period from 2003 to 2011. Using an integrated approach we find that the rate of mass loss from the region's glaciers increased from 11.1 ± 1.8 Gt a−1 (–270 ± 40 kg m−2 a−1) in 1963–2006 to 23.8 ± 3.1 Gt a−1 (–580 ± 80 kg m2 a−1) in 2003–2011. The doubling of the rate of mass loss is attributed to higher temperatures in summer with little change in annual precipitation. Through both direct and indirect effects, changes in summer temperatures accounted for 68–98 % of the variance in the rate of mass loss to which the Barnes Ice Cap was found to be 1.6 times more sensitive than either the Penny Ice Cap or the regions glaciers as a whole. Between 2003 and 2011 the glaciers of Baffin and Bylot Islands contributed 0.07 ± 0.01 mm a−1 to sea level rise, a rate equivalent to the contribution coming from Patagonian glaciers. Over the 48-year period between 1963 and 2011 the glaciers of Baffin and Bylot Islands contributed 1.7 mm to the world's oceans.

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