Image: NASA Earth Observatory (public domain)
Dr. Sebastian Lüning and Prof. Fritz Vahrenholt today here are asking how sea level rise is doing because as have not heard much about it lately. A good place to start is at Climate4You. Strangely the data go only until December 2016. And if you look at the data from the source form the University of Colorado, we find the same. So what’s with 2017?
The Silence of the Sea Level Rise
Today we know that satellite data must undergo a number of steps before a sea level rise figure can be reached. In April 2017 a study appeared in the Geophysical Research Letters, where corrections were made. As a result the average sea level rise since 1993 was not 3.3 mm/year, but rather 3.0 mm per year. This was hardly music to the hears of alarmists.
And what was really peculiar was the headline appearing in Nature concerning the study:
Satellite snafu masked true sea-level rise for decades
Revised tallies confirm that the rate of sea-level rise is accelerating as the Earth warms and ice sheets thaw.”
Here Nature unabashedly covered up the lower sea level rise. Also all the natural variability of ocean cycles was ignored. The reality is that there is no sign of an increased rate, as Willis Eschenbach at WUWT calculated. That’s been confirmed by a NASA study appearing in November 2017 in the Journal of Geophysical Research (Beckley et al. 2017):
On the “Cal-Mode” Correction to TOPEX Satellite Altimetry and Its Effect on the Global Mean Sea Level Time Series
Comparison of satellite altimetry against a high-quality network of tide gauges suggests that sea-surface heights from the TOPEX altimeter may be biased by ±5 mm, in an approximate piecewise linear, or U-shaped, drift. This has been previously reported in at least two other studies. The bias is probably caused by use of an internal calibration-mode range correction, included in the TOPEX “net instrument” correction, which is suspect owing to changes in the altimeter’s point target response. Removal of this correction appears to mitigate most of the drift problem. In addition, a new time series based on retracking the TOPEX waveforms, again without the calibration-mode correction, also reduces the drift aside for a clear problem during the first 2 years. With revision, the TOPEX measurements, combined with successor Jason altimeter measurements, show global mean sea level rising fairly steadily throughout most of 24 year time period, with rates around 3 mm/yr, although higher over the last few years.
As is the case with the global warming hiatus, there is now scrambling going on for ideas to explain the lack of sea level rise.
A press release issued by the National Science Foundation is floating the idea that volcanoes could be a reason. The idea ocean cycles might be playing a role obviously has not occurred to the NSF scientists.
Trust “taking a hit”
Vahrenholt and Lüning also write that with all the steps the satellite sea level data have to go through, it is “little wonder that trust in satellite measurements is taking a hit”. Mörner (2017) suggests putting less emphasis on satellite-based measurements and putting it more on coastal tide gauges (where people actually live). Tide gauges globally show a sea level rise rate of only 1.5-2 mm/year.
Also the future does not look anywhere near as bad as it is often portrayed. One reason is that scientists are anticipating increased snowfall over Antarctica, which stores huge amounts of water at the South Pole.
A few years ago Judith Curry stopped doing research and now consults companies and authorities on the subject of climate change. A number of clients have shown up at her door and asked her to submit a serious analysis of sea level rise over the recent decades and provide an estimate of what to expect in the future.
In a separate Part 2, Curry summarizes her findings:
The geological record for sea level rise provides important context for recent sea level rise. However, the uncertainties in the geological sea level record are substantial, associated with sparse sampling, uncertainties in the proxy methods and uncertainties in the analysis methods. Is the 20th century sea level rise unusual? Sea level was apparently higher at the time of the Holocene Climate Optimum (~ 5 ka), at least in some regions. I have not seen an overall assessment of this, but there have recently been numerous publications providing local evidence for higher sea levels during this period. Whether or not sea level was higher during the Medieval Warm Period than current levels remains uncertain, and there is substantial disagreement among different reconstructions on the sea level during the MWP, with the Grinsted et al finding substantially higher sea level values during the MWP (around 1150 AD). Kopp et al. find the 20th century rate of sea level rise to be the highest in the last 27 centuries. However, since their data is barely resolved at 100 year time scales (with decimeter vertical resolution), I would not place high confidence in their conclusion. Eyeball examination of Grinsted et al.’s Figure 7 shows possibly higher rate of sea level rise between ~1000 and 1100 AD. Overall, I find Kopp et al.’s analysis to be more convincing (apart from overconfidence in the relative rate of 20th century sea level rise). The pace of interesting and important paleo sea level rise research seems to have accelerated since publication of the AR5, I will be following this closely.”