Sea Level Rise: Just the Facts

The Maldives–Poster Child for rising Sea Levels

The three most mentioned evils of rising CO2 are Rising Temperatures, Declining Sea Ice and Rising Sea Levels.  Plateaus presently appearing in the first two have been discussed a lot here and elsewhere.  This post gives what you need to know about Sea Level alarms.

Sea level rise (according to NASA)

Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.

Dave Burton takes us underneath the hype and exposes the facts.  Below is his post originally at Tom Fuller’s website. David Burton puts it all in perspective from his location on the coast of North Carolina.  Much more info on sea levels is available at Dave’s own website linked below.

Sea-level rise is not accelerating, and has not accelerated since the 1920s.

There are about sixty good-quality, 100+ year records of sea-level around the world, and they all show the same thing: there has been no statistically significant acceleration (increase) in the rate of sea-level rise in the last 85 years or more. That means anthropogenic CO2 emissions do not measurably affect sea-level rise, and predictions of wildly accelerated sea-level rise are based on superstition, not science.

Here are two very high quality sea-level measurement records, one from the Pacific and one from the Atlantic:

With atmospheric CO2 at 0.040% by volume, globally averaged sea-level rise at the coasts is just under +1.5 mm/year.

When atmospheric CO2 was at 0.031% by volume, globally averaged sea-level rise at the coasts was just under +1.5 mm/year.

The difference is that climate alarmists think the current +1.5 mm/year is catastrophic and caused by human release of CO2, and the +1.5 mm/year 85 years ago was natural and inconsequential.

However, the similarity between the two numbers — the catastrophic 1.5 mm/yr and the inconsequential 1.5 mm/yr — has confused even some liberals into backing away from the One True Climate Faith. Even President Obama’s former Undersecretary for Science, Steven Koonin, has written that:

“Even though the human influence on climate was much smaller in the past, the models do not account for the fact that the rate of global sea-level rise 70 years ago was as large as what we observe today.”

Sea-level didn’t actually rise 3.39 mm last year, at the coasts.

That 3.39 mm number is from satellite altimetry measurements of the open ocean, inflated by the addition of model-derived GIA estimates. It has little relation to anything that matters.

Most fundamentally, satellite altimeters measure the wrong thing. Their measurements are distorted by “sea-level rise” caused by thermal expansion when the upper layer of the ocean warms. But that is a strictly local effect, which doesn’t affect the quantity of water in the oceans, and doesn’t affect sea-level elsewhere (e.g., at the coasts).

Sea-level rise only matters at the coasts, but satellite altimeters are incapable of measuring sea-level at the coasts. Tide gauges measure sea-level at the coasts, where it matters, and their data is of much higher quality.
The best tide-gauge records of sea-level measurements are nearly ten times as long as the combined satellite measurement record, and twenty times as long as any single satellite measurement record, and the tide-gauge records are trustworthy.

The satellite measurements of sea-level are not. They are subject to a long list of potential distortions, and vary considerably from one satellite to another.

Steve Case has documented how U.Col. has revised their satellite “measurements” of sea-level over the years:

The Envisat numbers were revised even more dramatically. Subsequent revisions to data up to ten years after it was recorded approximately tripled the rate of sea-level rise “measured” by Envisat.

NASA is aware of the problems with satellite measurements, and they’ve proposed a new mission called the Geodetic Reference Antenna in SPace (GRASP) to try to improve matters. However, that mission has not been funded.

References and additional information is here:

Footnote February 23, 2016

Dave Burton warned us above about superstitious sea level rises to come.  Prime example comes in Scientific American article gone viral in mass media.  The abstract of the study:

We present the first, to our knowledge, estimate of global sea-level (GSL) change over the last ∼3,000 years that is based upon statistical synthesis of a global database of regional sea-level reconstructions. GSL varied by ∼±8 cm over the pre-Industrial Common Era, with a notable decline over 1000–1400 CE coinciding with ∼0.2 °C of global cooling. The 20th century rise was extremely likely faster than during any of the 27 previous centuries. Semiempirical modeling indicates that, without global warming, GSL in the 20th century very likely would have risen by between −3 cm and +7 cm, rather than the ∼14 cm observed. Semiempirical 21st century projections largely reconcile differences between Intergovernmental Panel on Climate Change projections and semiempirical models.

My bolding is to draw attention to the basis in models not observations.  Further they say half the projected rise is due to thermal expansion which is a local effect not appearing at the coastline or on tidal gauges.

In ancient times people built idols in their own images and worshiped them to ensure more favorable weather and prosperity. Today those icons take the form of computer models whose prophecies are sure to scare the bejesus out of us.