Northern European Sea Level Rise. Aslak Grinsted Centre for Ice and Climate Niels Bohr Institute University of Copenhagen

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1 Northern European Sea Level Rise Aslak Grinsted Centre for Ice and Climate Niels Bohr Institute University of Copenhagen

2 Global Sea Level Rise The world is warming and this causes sea level to rise because: 1 Warming melts the large ice masses on Earth. AND WE SEE THIS HAPPENING 2 As the oceans are warming the water expands.

3 The Greenland Ice Sheet margins are thinning and outlet glacier flow has increased Elevation change Sørensen et al. (DTU-Space) Rignot et al Jakobshavn Negative total mass balance (TMB) Img Credit Konrad Smiarowski

4 The Antarctic Ice Sheet is losing mass (Especially WAIS) Pritchard et al Rignot et al At present, the Antarctic ice sheet is losing mass at a rate almost comparable to that of the Greenland ice sheet, about 250 ± 31 Gt/year

5 Glaciers and Ice caps are shrinking Small total volume (~0.5m) But very important because they can react fast to climate change Image created by Robert A. Rohde / Global Warming Art

6 Ocean Heat Content is increasing (3-year running mean) Levitus et al. 2012

7 As a consequence sea level is rising Tide-Gauges & Satellite altimetry Amsterdam only 20 th Century rate 1.8 mm yr -1 Satellite rate since mm yr -1 Tide-gauge rate since mm yr -1 Jevrejeva et al. 2008

8 Sea level rise is not uniform

9 Fennoscandian Glacial Isostatic Adjustment GIA Hill et al. (2010) combined estimate using data from GPS (bifrost), GRACE and Tide-gauges. ΔRSL = ΔLSL + ΔGIA

10 Thermal expansion and Dynamic Sea Level GHG forcing (A1B) will: Warm the ocean Redistribute salt in the ocean Small steric sea level rise in shallow continental shelf regions. However... Thermosteric Response Halosteric Response Landerer et al. 2007

11 Steric SSH gradient will drive a mass flux to shallow regions...

12 Net effect: Thermal expansion + DSL + Average of 3 CMIP3 models

13 GEOID fingerprints: Gravity, Elastic, Rotational Fractional Sea Level Rise Icesheet fingerprint from Bamber and Riva, Glacier fingerprint from Slangen et al.

14 Mountain Glaciers and Ice caps ~15 cm

15 Greenland Mass Loss 7+7cm Greenland from International Space Station. Credit: NASA

16 Antarctic Ice Sheet 21-7 cm Gargantuan Crack in Pine Island Glacier NASA/METI/ERSDAC/JAROS

17 Ground water mining and Reservoir impoundment 5 cm

18 Mid-range estimate, and High end Scenario * 15cm 7+7 cm 21-7 cm 22 cm

19 Best estimate (A1B, ΔGMSL=70cm) Local Sea Level Rise Glacial Isostatic Adjustment

20 Key uncertainties: DSL fingerprint Some models have ~30cm larger DSL response than the 3 high res models used.

21 Potentially large DSL Hosing response Ocean-model N.Atlantic Greenland melt = Freshwater water forcing of the N.Atlantic. This Hosing slows down AMOC and leads to an additional Atlantic DSL response. Ocean-only models predict this to be a minor effect in the Baltic (~2cm). Coupled AOGCMs exhibit a 5 times stronger response. (Stammer et al. 2011) Coupled AO-GCM N.Atlantic Stammer et al. 2011, Forced with 2mm/yr=5times present day Greenland mass loss

22 Key uncertainty: Anthropogenic Pathway and steric contribution

23 Key uncertainty: Antarctic Dynamical Response. Hellmer et al High-end 40-5 cm Antarctic Aurora from International Space Station. Credit: NASA

24 Constructed high-end scenario (~5% exceedance prob.) Key uncertainties for Regional Sea Level projections: Anthropogenic pathway (A1B/A2/RCP4.5/RCP8.5): +25% Global mean steric response. (22 cm 25 cm) Antarctic Mass Loss (14 cm 35 cm) Ground water pumping + Reservoir (5 cm 8 cm) Other uncertainties (DSL, Geoid, Hosing, Pressure, GIA, Wind, Run-off): (0 cm 20 cm) 18cm 24 cm 35 cm 25 cm 8 cm 20 cm

25 High-end estimate (for ΔGMSL = 127cm)

26 Budget-based projections are perhaps ~20 cm too low. A1B High-end (110cm) Mid-range (70cm)

27 Next centuries...

28 The Rødbyhavn tide gauge Water level relative to yearly mean sea level (cm) Protect against: 1.65m above projected mean sea level. What if: 50 cm error in sea level rise projection Consequence: Flooded every year! Infrastructure design criteria: Protect against 100yr storm surges.

29 Thank you... Questions?

30 Petermann Kangerdlussuaq Wide-spread Dynamical changes Jakobshavn Key dynamical processes not included in AR4-generation ice sheet models. (and wont be in AR5 either) Helheim

31 IPCC 2001; IPCC 2007 Sea-level rise will continue during the 21st Century Larger values cannot be excluded Sliding ice sheets (Greenland and Antarctica) Principally ocean warming and melting glaciers

32 How reliable are our sea level rise projections? Observed sea level rise tends to follow the uppermost dashed line of the IPCC scenarios, namely the one "including land ice uncertainty IPCC models underpredict rates of sea level rise by ~40% (Rahmstorf et al., 2007). Comparison of the 2001 IPCC sea-level scenarios (starting in 1990) and observed data. Church and White (2006) data based primarily on tide gauges (annual, red) and the satellite altimeter data (updated from Cazenave and Nerem 2004, 3-month data spacing, blue, up to mid-2006) are shown with their trend lines. Figure credit: realclimate.org