Past Sea Level Changes Part One
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Credits: Phil Woodworth Past sea level changes Part One Svetlana Jevrejeva National Oceanography Centre, Liverpool, UK sveta@noc.ac.uk Outline • Sea level changes from geological records • Instruments for the measurement of sea level • Tide gauge records, Data Centres, Specific data sets • Sea level observing systems (networks) • Interpretation of observations, synthesis of the data- global sea level rise, reconstructions • Sea level budget • Short conclusion Sea level changes from geological records http://www.ncdc.noaa.gov/paleo/ctl/clisci100k.html Sea level changes during the Late Holocene AR5 IPCC, 2013. Chapter 5, Figure 5.17 How unusual is the current sea level rate of change? AR5 IPCC, 2013. Chapter 5, FAQ5.2 Global sea level rise since 1700 Figure 13.27, AR5 IPCC ( 2013) Sea Level Expansion Glaciers Greenland Antarctica Land Water Climate Change 1712 – Steam engine by Thomas Newcomen (industrial use of coal) 1938 - Using records from 147 weather stations around the world, British engineer Guy Callendar shows that temperatures had risen over the previous century, link to the CO2 concentrations, suggesting that increase in CO2 caused the warming 1972 - First UN environment conference (chemical pollution, atomic bomb testing - no climate change), in Stockholm 1975 - US scientist Wallace Broecker puts the term "global warming" into the public domain in the title of a scientific paper 12 Dec 2015 – Paris Agreement on climate change (195 nations) Why do we make sea level measurements What do we measure? Coastal protection (extreme sea levels) Navigation (tide /shallow waters) Vertical land movement Instruments for the Measurement of Sea Level Automatic tide gauge at Port Protection, Prince of www.bidstonobservatory.org.uk/tide-gauges/ Wales Island, Alaska, 1915. Photo from NOAA Photo Library www.climate.gov/news-features/climate-tech/reading-between-tides- 200-years-measuring-global-sea-level Instruments for the Measurement of Sea Level IOC manual Two large stilling wells at Holyhead in North Wales, UK Instruments for the Measurement of Sea Level GPS for time Geostatic satellite antenna Tube for acoustic sensor Electronics box A NOAA water level monitoring station with an acoustic sensor on Dauphin Island, Alabama. A small GPS antenna enables precise timekeeping—not elevation tracking— and a second antenna transmits data to geostationary Radar gauge in Liverpool satellites. Photo courtesy Morgan McHugh The main limitation of tide gauge data Specific limitations: 1) Geographical locations 2) Vertical land movement/benchmark GPS at tide gauge locations King et al, 2012 Globally: 90% of tide gauge locations are not covered by GPS observations Remote measurements IOC manual Summary of commonly used methods for measuring sea level Category Type Wave averaging Accuracy Advantage Disadvantage Surface Tide pole By eye 0.02-0.10m Inexpensive, Effort, workforce following Easy to make Float Stilling well 0.01-0.05m Robust Needs vertical structure, high maintanance Fixed sensors Acoustic Multiple 0.005-0.01m Robust, low Needs vertical structure reflection samples cost, low maintenance Radar reflection Pressure Hydrodynamics 0.01m No vertical Density and wave corrections, high and multiple structure is maintance samples needed Remote Satellite Empirical 0.01m Systematic Expensive, specialist use only, multiple adjustment global corrections, misses local storms, does not coverage sample near the coast IOC Manual http://www.psmsl.org/train_and_info/training/manuals/manual_14_final_21_09_06.pdf Tide gauge data 1. Permanent Service for Mean Sea Level (PSMSL) 2. National data centres, Local Authorities 3. Global Observing Sea Level System (GLOSS) 4. Data for Geophysical signals (e.g. SONEL) 5. Specific tide gauge data sets (e.g. high frequency data) ! Please acknowledge use of any data in your publications Permanent Service for Mean Sea Level (PSMSL) From PSMSL, www.psmsl.org Evolution of the PSMSL dataset RLR (Datum Controlled) Dataset From PSMSL, www.psmsl.org Sea level measurements in Arctic Henry et al, 2012. Regions not covered by satellite altimetry Blue – active after 2006 White- discontinued since 2006 Longer RLR Records From PSMSL, www.psmsl.org Historical data Number of the tide gauge measurements available since 1807 Since 1900 From PSMSL, www.psmsl.org www.psmsl.org Land movement signals SONEL http://www.sonel.org/-Sea-level-trends-.html Local vertical land movement King et al, 2012 Global Sea Level Observing System (GLOSS) GLOSS is a programme of the IOC and WMO with primary aim to increase quantity and quality of data to PSMSL High Frequency data 1) GLOSS Delayed Mode Higher Frequency (DM HF) Data Sets • British Oceanographic Data Centre (BODC) https://www.bodc.ac.uk/data/hosted_data_systems/sea_level/international/ • University of Hawaii Sea Level Center (UHSLC), http://uhslc.soest.hawaii.edu/ 2) GLOSS Fast Mode Higher Frequency Data Sets, at the UHSLC 3) IOC Operational Status and Quick Inspection, Sea Level Monitoring Facility http://www.ioc-sealevelmonitoring.org/ 4) National and International Data Centres http://www.psmsl.org/links/programmes/ IOC Operational Status and Quick Inspection, Sea Level Monitoring Facility http://www.ioc-sealevelmonitoring.org/ Associated data sets (GIA, as an example) GIA models are available from several scientists: • Richard Peltier (University of Toronto) has made available his ICE-5G (VM2) and ICE-5G (VM4), ICE 6G relative sea level predictions http://www.psmsl.org/train_and_info/geo_signals/gia/peltier/index.php • Jerry Mitrovica (Harvard University) • Kurt Lambeck (Australian National University) • Giorgio Spada Free Associate Professor of Physics of the Earth, DiSPeA, Urbino University, Italy Use of the tide gauge data sets TAR IPCC (2001): “… Based on tide gauge data, the rate of global average sea level rise during the 20th century is in the range 1.0 to 2.0 mm/yr, with a central value of 1.5 mm/yr (as with other ranges of uncertainty, it is not implied that the central value is the best estimate). Estimates of the 20th century sea level rise from “selected” locations Buenos Aires 1987 Balboa 1996 Cristobal 1980 Quequen 1982 Douglas, 1997 Estimates of the 20th century sea level rise from “selected” locations Douglas, 1997 Table 1. From Douglas, 1997 ICE 3G San Francisco 1.5 -0.1 (-0.4) 1.6 (1.9) ICE 5G, [Peltier, 2004] Santa Monica 1.4 0 (-0.7) 1.4 (2.1) La Jolla 2.1 -0.1 (-0.6) 2.2 (2.7) San Diego 2.1 -0.1 (-0.6) 2.2 (2.7) 1.8 (2.4) Estimates of the 20th century sea level rise Douglas, 1997 Figure 3.13, AR5 IPCC, chapter 3 Reconstructions (Virtual station) Regional average wpacific Individual tide gauge records Jevrejeva et al., 2014 Binomial tree to illustrate the ‘virtual station’ stacking method. Top-node represents the regional average, bottom nodes the tide gauge records, and rest of nodes are virtual stations. Grinsted et al., 2007 Estimates of the 20th century sea level rise TAR IPCC (2001): “… Based on tide gauge data, the rate of global average sea level rise during the 20th century is in the range 1.0 to 2.0 mm/yr, with a central value of 1.5 mm/yr (as with other ranges of uncertainty, it is not implied that the central value is the best estimate). AR4 IPCC (2007): “…For the 20th century, the average rate was 1.7 ± 0.5 mm/yr, consistent with the TAR estimate of 1 to 2 mm/yr”. AR5 IPCC (2013): “It is very likely that the mean rate was 1.7 [1.5 to 1.9] mm/ yr between 1901 and 2010 for a total sea level rise of 0.19 [0.17 to 0.21] m. Between 1993 and 2010, the rate was very likely higher at 3.2 [2.8 to 3.6] mm/yr; similarly high rates likely occurred between 1930 and 1950”. New estimate of global sea level rise by Hay et al., 2015 Time series of GMSL for the period 1900–2010. CC Hay et al. Nature 000, 1-4 (2015) doi:10.1038/nature14093 New estimate of sea level rise from Dangendorf et al., 2017 Short summary Tide gauge observations, observational networks and data sets • Since 1700 instrumental records provide information about sea level rise and variability • In addition to climate related application, tide gauges are used for Tsunami and storm surges warning systems, Satellite altimetry calibration; Navigation (including tidal predictions) Civil engineering, coastal defences, survey and others. Data • Monthly mean sea level data – PSMSL/global; National authorities/local • GLOSS, High- frequency (IOC, University of Hawaii Sea Level Centre, British Oceanographic Data Centre • GPS data for GLOSS and PSMSL - SONEL References Handbook of Sea-Level Research edited by Ian Shennan, Antony J. Long, Benjamin P. Horton IOC Manual http://www.psmsl.org/train_and_info/training/manuals/manual_14_final_21_09_06.pdf Reconstructions ( Data from http://www.psmsl.org/products/reconstructions/) Global Sea Level Reconstruction by Church and White, GRL 2006, with an update in 2011. Global Sea Level Reconstruction 1807-2002 by Jevrejeva et al., JGR 2006. Global Sea Level Reconstruction 1700-2002 by Jevrejeva et al., GRL 2008. 1900-2009 Global Sea Level Reconstruction from Ray and Douglas, Prog. Oceanogr. 2011. Global Sea Level Reconstruction 1807-2010 by Jevrejeva et al., GPC 2014. Reconstructions Hay CC, Morrow E, Kopp RE, Mitrovica JX (2015) Probabilistic reanalysis of twentieth century sea-level rise. Nature 517:481–484. (Data are available from Nature) Dangendorf, S, M Marcos, G Wöppelmann, CP Conrad, T Frederikse, R. Riva (2017) Reassessment of 20th century global mean sea level rise, Proceedings of the National Academy of Sciences, 201616007. Credits: Aslak Grinsted Part TWO Understanding of past sea level changes Svetlana Jevrejeva National Oceanography Centre, Liverpool, UK Outline • Motivation for understanding of the past sea level changes • Sea level budget Motivation May 14, 2002, Proceedings of the National Academy of Sciences (PNAS) Twentieth century sea level: An enigma Walter Munk “….Sea level is important as a metric for climate change as well as in its own right.