Veijo Pohjola, professor i naturgeografi/ glaciologi,
Uppsala universitet,
Institutionen för geovetenskaper,
Geocentrum

By
Arctic Monitoring and Assessment Programme (AMAP) www.AMAP.no/SWIPA

A warmth record in surface air temperatures in the Arctic 2005-2010
• Surface air temperatures
(SAT) 2005 -2010 are higher than any other 5 yr period since SAT records began with IPY 1 in 1882
• The increase in SAT in the
Arctic is twice the global average increase in SAT
• Powerful feedbacks mechanisms due to albedo effects with less sea ice cover and shorter periods with snow cover is a likely responsible agent

Arctic warming is pronounced winter and fall

Predictions for the future

Threats:
• Melting permafrost increases the carbon release to the atmosphere.
• Methane (CH
4
) release is a positive feedback (marine permafrost),CO
2 unclear mechanism.
• Between 1970 and 2005 did the permafrost ”front” move northwards with 1 km / year in Siberia .
• Thawing permafrost gives large challenges for infrastucture in areas with high retreat rates.

Toreti et al. 2014. DOI: 10.1002/grl.50940
2060-2099
2020-2059
Winter RCP8.5
Summer RCP8.5
Figure 3. Zonal mean changes of the estimated 50 year return levels (%) with respect to the period 1966 –2005 in (a) winter and (b) summer under the RCP8.5 scenario. Blue and green lines represent the ensemble mean for the periods
2020 –2059 and 2060–2099, respectively. Blue and green shaded areas show the intermodel variability for the periods
2020 –2059 and 2060–2099, respectively. The ensemble mean and the intermodel variability are plotted only when at least six models out of eight provide at least 75% of reliable grid points for the zonal mean.

SWE = snow water equivalent
SCD = snow cover duration

Multi-Decadal Changes in Snow Characteristics in Sub-Arctic Sweden.
C. Johansson, V.A.Pohjola, C.Jonasson, T.V. Callaghan. 2011.
AMBIO, 40:566–574, DOI 10.1007/s13280-011-0164-2

Ecosystems will change; some species are losers,
Some are winners, at least, temporarily.
Cod and herring are two predicted winners, while pacific salomon, some species of seals and polar bears are losers.

The State of the Large Ice Sheets

Glacier contribution to SLR
IPCC 2013

The SWIPA Report, 2011

a , The large-scale ocean circulation around Greenland, indicating the major currents and basins. Atlantic-origin water pathways, red to yellow; Arctic-origin freshwater pathways, blue 41 . The dynamic thinning of Greenland is superimposed 19 . b , Heat content anomaly estimates in the North Atlantic as a whole and c , separated into tropical and subtropical and d , subpolar contributions over the period 1960 –2010 (ref. 32 ). Extremely sparse observational coverage below 700 m depths over much of the period adds significant uncertainties.

Ice-dynamic projections of the Greenland ice sheet in response to atmospheric and oceanic warming by J. J. Fürst, H. Goelzer, and P. Huybrechts
The Cryosphere, 9, 1039–1062, 2015 www.the-cryosphere.net/9/1039/2015/ doi:10.5194/tc-9-1039-2015

Tidewater Glacier Mechanisms (IPCC
AR5)

Century-scale simulations of the response of the
West Antarctic Ice Sheet to a warming climate by Cornford et al., 2015, TC,9
Abstract
We measure the grounding line retreat of glaciers draining the Amundsen Sea sector of West Antarctica using Earth Remote Sensing (ERS-1/2) satellite radar interferometry from 1992 to 2011.
• Pine Island Glacier retreated 31 km at its center, with most retreat in 2005 –2009 when the glacier ungrounded from its ice plain.
• Thwaites Glacier retreated 14 km along its fast flow core and 1 to 9 km along the sides. Haynes Glacier retreated 10 km along its flanks.
• Smith/Kohler glaciers retreated the most, 35 km along its ice plain, and its ice shelf pinning points are vanishing.
• These rapid retreats proceed along regions of retrograde bed elevation. Upstream of the 2011 grounding line positions, we find no major bed obstacle that would prevent the glaciers from further retreat and draw down the entire basin.
Pine Island
Thwaites
Smith / Kohler

Century-scale simulations of the response of the
West Antarctic Ice Sheet to a warming climate by Cornford et al., 2015, TC,9
Figure 8. Change in volume above flotation (V (t)) in the Amundsen Sea Embayment during the melt rate anomaly experiments
.
Our most extreme simulation of widespread dynamic thinning in West Antarctica’s fast-flowing ice streams results in 200mm of eustatic sea level rise by 2100 and 475mm by 2200. Pine Island and Thwaites Glaciers see their grounding lines retreat by hundreds of kilometers, as do the Möller, Institute, Evans, MacAyeal, Bindschadler, Whillans and Mercer ice streams and to a lesser extent Carlson Inlet and the Rutford Ice Stream.

The multi-millennial Antarctic commitment to future sealevel rise by Golledge et al. 2015
Nature 526(15 October 2015) DOI:doi:10.1038/nature15706
Figure 2. Antarctic contribution to Global Mean Sea Level. a , Predicted sea-level contribution from the Antarctic ice sheet for ‘high’ and ‘low’ simulations (coloured lines) under each of the four
RCP scenarios (darker shading), based on coeval climatic and oceanic perturbations. The forced response (grey shading) represents 20% to 36% of the committed response by 5000 ce. Lighter shading between coloured lines shows rates of sea-level-equivalent ice loss for each scenario.

Range by
IPCC
2013

Range by
IPCC
2013
+WAIS?

Century-scale simulations of the response of the
West Antarctic Ice Sheet to a warming climate by Cornford et al., 2015, TC,9

The multi-millennial Antarctic commitment to future sealevel rise by Golledge et al. 2015
Nature Volume: 526, Pages:421 –425 Date published:(15 October 2015)
DOI:doi:10.1038/nature15706 a , Predicted sealevel contribution from the Antarctic ice sheet for ‘high’ and ‘low’ simulations (coloured lines) under each of the four RCP scenarios (darker shading), based on coeval climatic and oceanic perturbations. The forced response (grey shading) represents 20% to 36% of the committed response by 5000 ce. Lighter shading between coloured lines shows rates of sea-level-equivalent ice loss for each scenario. b , Long-term sea-level commitment as a function of atmospheric warming (blue shading with squares). Intermediate response curves for the ‘low’ simulations are shown as dotted lines. Red shading with triangles shows the relationship between iceshelf area and atmospheric warming for the near-equilibrium response and for intermediate stages (dotted lines).
All curves in b are based on data from the four RCP scenario simulations, further constrained by two additional experiments whose maximum air temperature forcings are 1.5 ° C and 3.35 ° C. Pink shading defines the temperature range within which an ice shelf extent that is less than 50% of the present extent is simulated.

The multi-millennial Antarctic commitment to future sealevel rise by Golledge et al. 2015
Nature Volume: 526, Pages:421 –425 Date published:(15 October 2015)
DOI:doi:10.1038/nature15706
Emissions-forced climate warming to 2100 ce ( a , d , g , j ) and 2300 ce ( b , e , h , k ) results in initial sea-level contributions from
Antarctica that are only a small proportion of the total sea-level commitment by 5000 ce
( c , f , i , l ). Magnitudes and rates of sea-level contributions are shown for each panel.
Leading values and those in parentheses relate to ‘low’ and ‘high’ scenarios respectively. Ice extent for ‘low’ simulations is shown in white; blue lines show groundingline locations for ‘high’ simulations. Pale blue shading shows grounded ice lost in ‘high’ simulations but present in the ‘low’ scenario. Note the increasing divergence between ‘high’ and
‘low’ beyond 2300 ce. Grey texturing indicates areas of relatively faster-flowing ice. WAIS, West Antarctic Ice Sheet; EAIS,
East Antarctic Ice Sheet; FRIS, Filchner –
Ronne Ice Shelf.

Ice-dynamic projections of the Greenland ice sheet in response to atmospheric and oceanic warming by J. J. Fürst, H. Goelzer, and P. Huybrechts