Effects of Climate Change on Sea Level Ole B. Andersen
Acknowledgement: P. Knudsen, P. L. Svendsen E. Leuliette(NOAA), G. Piccioni(TUM)
Outline • Climate change, IPCC and sea level. • Data behind the IPCC sea level estimates – Satellite altimetry and tide gauges. • Global sea level change (shorter – longer times – sea level reconstruction) • Explaining current sea level changes / Global sea level budget. • Regional sea level change. Arctic ocean. Future of sea level research.
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Future climate change
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Climate Change IPCC Assessment Report 5 provides a new assessment of sea level rise: • Climate scenarios:
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Climate Change IPCC Assessment Report 5 provides a new assessment of sea level rise: • Projections for 2013 - 2100
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
SEA LEVEL PROJECTIONS CURRENTLY HAVE LARGE UNCERTAINTIES…….. 7
DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
PSMSL tide gauges
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Tide gauges measures relative SL
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7100
7050
7000 1900
1920
1940
1960
1980
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1960
1980
2000
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7050
6950
1900
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NKG Summer School Båstad, Sweden, 2016
Satellite Altimetry measures geocentric sea level
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Global is only “global up to 65”
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Regional sea level change (1993-2011)
2003-2011
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Errors.
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Longer time series. Beyond the altimeter era
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Tide Gauge analyses Global reconstructed sea level Church & White 2 y = +1.41x, r =0.944
100
2
y = +1.65x, r =0.958 2 y = +1.89x, r =0.910
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-100
1860 19
1890
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DTU Space, Technical University of Denmark
1950
1980
2010 NKG Summer School Båstad, Sweden, 2016
Salt Marsh
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NKG Summer School Båstad, Sweden, 2016
Understanding Sea level change The Sea Level Budget
What changes sea level 1) Heatig water (Steric expansion->height) 1) Adding water (ocean Mass) ∆SSH = ∆SH + ∆OM
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Little more sophisticated version.
∆SSH = ∆SH + ∆OM + ∆Circulation + ∆Shape 22
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NKG Summer School Båstad, Sweden, 2016
Large Ice bodies on the Earth.
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Climate Change IPCC Assessment Report 5 provides a new assessment of sea level rise: • Global sea level budget:
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
High spatial correlation.
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NKG Summer School Båstad, Sweden, 2016
Closing the budget. What can altimetry, GRACE, and Argo tell us? The sea level budget 2005-2015 may be expressed as height changes from the main components of sea level change:
∆SSH = ∆SH + ∆OM
SSH = sea surface height, SH = steric height, OM = ocean mass
Argo measures temperature and salinity short of the abyssal ocean (roughly 44 to 75% of Argo profiles are from 2000m). ∆SH = ∆SH(0–2000m) + ∆SH(2000m–∞) We can estimate a residual from observations: ∆SLresidual = ∆SSH – ∆SH(0–2000m) – ∆OM ∆SLresidual = ∆SH(2000m–∞) + Error 27
DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
GRACE and ARGO Satellites (MERIS on ENVISAT etc etc WILL ONLY GIVE YOU SEA SURFACE temperature You need to DIVE INTO THE ocean to get ”correct steric contribution”
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GRACE measure how gravity is changing because shape of our planet is changing.
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Global and regional sea level budgets
Global sea level budgets can be closed within the estimated errors Bounds size of deep (> 2000 m) ocean warming (e.g. Llovel et al. 2014) What do regional sea level budgets tell us? 30
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BAMS, State of the Climate 2014, [2015]
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Pacific Ocean sea level budget
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Arctic Ocean Feb.
Arctic Ocean problems: Seasonal to permanent ice cover Ocean tide models less accurate (sun-syncronous ERS/ENVISAT/C2/S3) range corrections affected by ice, retracking is challenging 32 DTU Space, Technical University of Denmark NKG Summer School residual orbit errors Båstad, Sweden, 2016
Altimetry – new re-processed 23Y dataset (ESA-CCI2)
Data availablility: RADS standard along-track products relative to DTU13 MSS
Data availablility: Re-processed along-track products relative to DTU13 MSS
Western Arctic/Beaufort: average data increases of 383%. 33 DTU Space, Technical University of Denmark NKG% Summer School (74N-80.5N, 130W-180W) on average data increase of 130
Båstad, Sweden, 2016
23 Years Linear Sea Level trend (1993-2015)
Average linear trend 2.2 mm/year but large inter-annual variations 34
DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Sea level change over past 60 years. Arctic sea level reconstruction 106 PSMSL Tide Gauges
Currently 40% Norwegian/Swedish Coast 50% Russian Coast 10 % Canada/Greenland etc 35
DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
900
>900 km
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NKG Summer School Båstad, Sweden, 2016
Altimetry+TG recon (1950-2010) Ray and Douglas approach
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Arctic SL reconstructed trend 1950 – 2010 (65-82N) EOF
Trend (mm/y)
Error (mm/y)
Church/White(Kaplan)
0
0.4
0.4
Church/White(Kaplan)
0-8
4.3
0.4
Ray /Douglas
0
2.0
0.3
Ray/Douglas
0-8
1.9
0.3
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Regional Arctic sealevel budget.
The sea level budget may be expressed as height changes using the main components of sea level change:
∆SSH = ∆SH + ∆OM SSH = sea surface height, SH = steric height, OM = ocean mass from GRACE (JPL-MASCONS) Halosteric component is the main contributor No ARGO data are available Steric signal from NOAA model -> 2005-2015 period.
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NKG Summer School Båstad, Sweden, 2016
Closing the Arctic Sea Level budget (2005-2015 -> early attempt)
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Summary – Future Essential: GGOS, Longer time series, >lowers uncertainty > improves prediction.
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Gain new knowledge about Sea level (sub-mesoscale)
Improved spatio temporal mapping of sea level. GEROS
Wickert, Andersen et al. 2016 43
DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
SWOT 2020 • Full SAR interferometry • altimetry
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DTU Space, Technical University of Denmark
NKG Summer School Båstad, Sweden, 2016
Thank you. Questions ??????
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DTU Space, Technical University of Denmark
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