Tuesday, October 7, 2014

New paper shows global sea level rise has greatly decelerated since ~2002, opposite of predictions

A new discussion paper published in Ocean Science evaluates multi-mission satellite sea level records and shows that the rate of sea level rise has greatly decelerated since ~2002, as has been documented in prior research finding sea level rise decelerated 31% since 2002, and decelerated 44% since 2004 to less than 7 inches per century. This is obviously the opposite of climate model predictions in response to a steady rise in CO2 greenhouse gas levels, but is compatible with the ongoing "pause" of global warming. 

Other notable findings from the paper include:

1) The positive global sea level rise trend is almost entirely due to an apparent huge "bulge" located in the Western equatorial Pacific region [Fig 12 immediately below, and the "bulge" 3-D illustrated by StevenGoddard.wordpress.com in the 3rd figure below]. 

2) Conversely, all areas shown in blue have experienced a drop in altimetric sea levels [different from relative sea levels which are more dependent upon land height changes] from 1993-2010, including most of the East and West coasts of North and South America. 

3) As the 2nd figure below indicates, this "bulge" is almost entirely steric sea level rise from thermal expansion, as opposed to eustatic sea level rise from melting of ice. The fact that the "bulge" is so localized in the equatorial Western Pacific points to trade winds or ocean oscillations such as the Pacific Decadal Oscillation as responsible, rather than any effect from greenhouse gases, which would cause a generalized, not highly localized, effect on ocean thermal expansion or eustatic sea level rise from melting ice.

4) The 4th figure below shows an alternative method of determining sea level rise using ARGO + GRACE finds sea levels rising at 2.31 mm/yr, about 35% less than determined by the satellite altimetry methods.

5) The 5th figure below [Figure 10 of the paper] shows sea level rise has greatly decelerated since ~2002, as has been documented in prior research. This is the opposite of climate model predictions in response to a steady rise in CO2 levels, but is compatible with the ongoing "pause" of global warming. 

6) Figure 7 below shows how easy it is to tamper with previously published satellite data from the European ENVISO satellite, which previously showed sea levels rising at 1.59 mm/yr [very similar to what global tide gauges show], but a convenient new processing algorithm magically increases or up-justs the rate of ENVISO sea level rise by 86% to match the US satellite data of 2.96 mm/yr. It's deja vu all over again.

Ocean Sci. Discuss., 11, 2029-2071, 2014

M. Ablain1, A. Cazenave2, G. Larnicol1, M. Balmaseda11, P. Cipollini7, Y. Faugère1, M. J. Fernandes10,14, O. Henry2, J. A. Johannessen3, P. Knudsen6, O. Andersen6, J. Legeais1, B. Meyssignac2, M. Picot12, M. Roca8, S. Rudenko9, M. G. Scharffenberg4, D. Stammer4, G. Timms5, and J. Benveniste13
1Collecte Localisation Satellite(CLS), Ramoville Saint-Agne, France
2Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (LEGOS), Toulouse, France
3Nansen Environmental and Remote Sensing Center (NERSC), Bergen, Norway
4University of Hamburg, Hamburg, Germany
5CGI, London, UK
6Technical University of Denmark (DTU), Lyngby, Denmark
7National Oceanography Centre (NOC), Southampton, UK
8isardSAT, Barcelona, Catalunya, Spain
9Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
10Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal
11European Centre for Medium-Range Weather Forecasts (ECMWF), Reading, UK
12Centre National d'Etudes Spatiales (CNES), Toulouse, France
13European Space Agancy (ESA), ESRIN, Frascati, Italy
14Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, 4050-123 Porto, Portugal

Abstract. Sea level is one of the 50 Essential Climate Variables (ECVs) listed by the Global Climate Observing System (GCOS) in climate change monitoring. In the last two decades, sea level has been routinely measured from space using satellite altimetry techniques. In order to address a number of important scientific questions such as: "Is sea level rise accelerating?", "Can we close the sea level budget?", "What are the causes of the regional and interannual variability?", "Can we already detect the anthropogenic forcing signature and separate it from the internal/natural climate variability?", and "What are the coastal impacts of sea level rise?", the accuracy of altimetry-based sea level records at global and regional scales needs to be significantly improved. For example, the global mean and regional sea level trend uncertainty should become better than 0.3 and 0.5 mm year−1, respectively (currently of 0.6 and 1–2 mm year−1). Similarly, interannual global mean sea level variations (currently uncertain to 2–3 mm) need to be monitored with better accuracy. In this paper, we present various respective data improvements achieved within the European Space Agency (ESA) Climate Change Initiative (ESA CCI) project on "Sea Level" during its first phase (2010–2013), using multi-mission satellite altimetry data over the 1993–2010 time span. In a first step, using a new processing system with dedicated algorithms and adapted data processing strategies, an improved set of sea level products has been produced. The main improvements include: reduction of orbit errors and wet/dry atmospheric correction errors, reduction of instrumental drifts and bias, inter-calibration biases, intercalibration between missions and combination of the different sea level data sets, and an improvement of the reference mean sea surface. We also present preliminary independent validations of the SL_cci products, based on tide gauges comparison and sea level budget closure approach, as well as comparisons with ocean re-analyses and climate model outputs.

1 comment:

  1. http://wattsupwiththat.com/2014/10/30/new-paper-on-sea-level-rise-purkey-et-al-2014-examines-the-sea-level-rise-by-basin/

    Residual rise only 1.5mm/yr