Malicious Claims of Sea Level Rise

Malicious Claims of Sea Level Rise...

One of the more malicious claims made by climate alarmists concerns sea level rise, misleadingly dramatized on the September, 2013 cover of the National Geographic magazine.

More recently, NOAA published an article claiming that sea level rise in the next 30 years would equal the rise of the past 100 years.

It’s very unfortunate that the US government would publish alarmist material. 

The NOAA report was thoroughly debunked by Joseph D’Aleo, CCM, co-founder and first Director of Meteorology at the cable TV Weather channel. (See below for link)

In addition, much of the apparent sea level rise cited in the NOAA report is due to subsidence, not climate change.

Publishing misleading and gratuitous information erodes the trust people place in their government.

Apparent Sea Level Rise

To understand the history of sea level rise, consider the migration of people over the land bridge connecting Russia and Alaska around 14,000 years ago, near the beginning of the Holocene Epoch in which we now live.

Today, there is no land bridge and the waters separating Russia from Alaska, other than coastal waters, are at least 90 feet deep. 

What happened? 

Sea level rise, mainly attributable to the melting of glaciers. 

This graph shows the rapid rise of sea levels as the ice started to melt, and then how it slowed as the volume of glacier ice diminished.

Recent Sea Level Rise

As seen from the chart, sea levels over the past 2,000 years have leveled off and risen more slowly.

For the past several hundred years, sea levels have risen, on average, around 8 inches every 100 years.

But, sea level rise hasn’t been constant. For example, sea levels were probably slightly higher during the Medieval Warm Period around 900 years ago, and slightly lower during the Little Ice Age 300 years ago.

More recent estimates of sea level rise are listed in this table from Judith Curry’s paper on the subject of sea level rise during the 20th century. (See below for link)

While these estimates vary substantially, in reality, the differences don’t mean very much in terms of the effect of sea level rise on society.

For example:

A rate of sea level rise of 1,9 mm/yr equates to 7.5 inches per century, while 1.1 mm/yr equates to 4.3 inches per century.

Sea level rise of 7.5 inches is only 3/4 inch in ten years, while a rise of 4.3 inches is less than 1/2 inch in 10 years.

Putting this in perspective, a copper penny is 1.52 mm thick, which is roughly the average sea level rise each year.

While certain areas can be more severely affected than others, on average, a penny’s thickness rise per year is manageable.

Here are the primary causes of apparent sea level rise:

  • Water temperatures:

Water temperatures vary with climate, but also with changing conditions such as La Niñas and El Niños.

  • Subsidence:

Subsidence is where the land sinks such as in Southern Florida, along the mid-Atlantic coast, and the area around the East Texas Gulf coast. 

  • Isostatic rebound.

During the last glaciation, glaciers covered huge land areas across North America and Europe, depressing the land under the weight of mile-thick ice creating a bowl-like depression.

The melting of the glaciers produced the effect referred to as isostatic rebound. 

With the melting of the glaciers, the land rises where it had been depressed by the weight of the glaciers, but falls at the periphery where bulging had raised the land.

  • Ice melt from glaciers.


More about subsidence, because some of the causes of subsidence are relatively new, such as water extraction from aquifers and oil and natural gas extraction from reservoirs. 

Subsidence results in flooding, and flooding gets the most attention in the media.

A good example is Miami, Florida, where alarmists have published videos showing the flooding of streets at high tide, without mentioning that subsidence is a major cause of flooding. 

Similar videos have been made along the North Carolina coast.

In both instances the land is sinking, primarily due to the pumping of water from the aquifer.

Other areas along the East and Gulf Coast where subsidence is an issue include:

  • Texas Galveston 4.7 mm/yr
  • Grand Isle LA      7.0 mm/yr
  • Baltimore            1.4 mm/yr
  • NY City               1.3 mm/yr
  • New Jersey – Chesapeake Bay Region 1.1 to 4.8 mm/yr 

Satellite measurements

Satellite measurements of sea level have only been available since 1992 and they show a rise of 3 mm/yr, or 12 inches per century. A one-foot rise over 100 years is still very manageable.

At this point, satellite data is suspect due to variables such as wave height, the complexities of translating raw satellite data, and because longterm satellite data is lacking.


Data shows that sea level rise is not a threat to mankind.

However, the media and alarmists point to local flooding to scare people into believing otherwise.

Subsidence can be the most important contributor to local flooding in some areas around the world.

In some locations, such as the New York City area, memorialized by the National Geographic cover, both subsidence and isostatic rebound are at play.

Sea level rise is a long-term process with multiple causes, and is not the result of climate change caused by the burning of fossil fuels.

D’Aleo rebuttal 

Judith Curry Paper

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