Are Sea Levels Rising?

Reading a National Geographic article on sea level rise reminds me of some of the things in my post about how to make good scientific measurements (and how not to): measuring equipment needs to be consistent or well-calibrated over many years.  This particular article talks about records and measurements going back to 1880.  I am not suggesting there is no sea level rise, just how much we are scientifically certain about and whether the records are representative of what is going on across the entire world.

The claim is that there is a 3.2 mm (about 1/8th of an inch) rise each year and that the rate is increasing. As with global temperature changes, one rarely sees in mainstream journals whether or not levels have ever dropped or whether they are located evenly across the globe so that they are a good indicator of global levels, as opposed to just several local ones.  For example, according to one source, Poland has the world's the oldest tide gauge, which provides records back to 1808. In the United States, the farthest back is 1856 when two tide gauges were put in operation with one in New York and one in San Francisco.  That's not very much coastline to do make many claims about global changes.  One must assume then, that indirect or proxy measurements are used for sea levels during this era and prior to it.  Indirect measurements are not as accurate as direct measurements.

A look at the Permanent Service for Mean Sea Level (PSMSL) map clearly shows the many modern accurate measurements only go back 30 years.  (Click on "Series Length" to see in black the number of sites that go back less than 30 years.)  Very few go back more than 100 years--especially in the Western Hemisphere and Australia.

One also must account for rising and sinking of the land--which was discovered and now determined by satellite measurements.  For example, Vienna and New Orleans are sinking and Alaska and Scandinavia are rising.  We don't know for sure what areas were doing prior to being able to make such land movement measurements.   Are those measures as accurate as they are now in terms of both rising and falling, and in terms of when those rises and falls occurred?

Additionally, if one is to say man-made warming is causing sea level changes, he or she must all account for sea level changes caused by:

• The tides, caused by the moon
• Large and small waves caused by wind and the tides
• High- and low-pressure areas in the atmosphere, which change the surface level of the ocean
• Temperature changes in the ocean, which change the density and volume of the water
• Rainfall and river water flowing into the ocean

Again, the current hysteria about future flooding disasters along the coasts could be correct, but given all the uncertainty about how much rise is occurring what is causing any claimed rise needs to be looked at critically--and reported, which it is not.

Good science requires one to also look at how that data is aggregated and look at claims that are contrary to the current view.  A 2017 peer reviewed article claims that some sea levels are actually stable:

The reconstructed tide gauge records of Aden, Mumbai and Karachi are perfectly consistent with multiple lines of evidence from other key sites of the Indian Ocean including Qatar, Maldives, Bangladesh and Visakhapatnam. The sea levels have been stable since the start of the twentieth century in Aden similar to Karachi and Mumbai.

This article did not get much press coverage in 2017, but it should have.  Additionally, this finding is in direct opposition to what the data looks like after it was aggregated by the PSMSL.  The authors are very direct, saying, the adjustments are "highly questionable" and "suspicious" because there are no scientific reasons for them, and that "the adjustments are always in the direction to produce a large rise in sea level."

If these accusations are true, not only are sea levels in certain areas not rising, but data to suggest rising sea levels is being falsified to give that particular result.  Definitely not good science.

Much more of this peer reviewed article is quoted here.