Coastal Flooding is Us Finds New Study

February 23, 2016 – Global sea levels go up and down and if you are a Republican running for the President of the United States, that’s all you need to know. But scientists researching that up and down over 2,800 years have drawn some disturbing conclusions. Never in the last 2,800 years have sea levels behaved as they have since the mid-20th century. In a comprehensive study of sea level index points assembled from around the globe, involving a group of researchers for more than a decade, published results appear in the Proceedings of the National Academy of Sciences of the United States of America.

They conclude that the rise in sea level in the 20th century was “likely faster than during any of the 27 previous centuries.” With 95% certainty, half of the more than 13.8 centimeter (plus 5 inches) mean sea level (MSL) rise can be attributed to human influence on global temperatures. This is the first comprehensive study to assess the relationship between air temperature and MSL. In the graph below the results of the research shows sea level rise and fall by century. Note the anomalous spike in MSL in the last century.

The cause, state the scientists, is trapped atmospheric heat which is causing ice sheets, glaciers and sea ice to melt. In analyzing the findings a new report states that more than two-thirds of coastal floods in the United States between 1950 and 2014 can be directly ascribed to human influenced MSL rise. States Ben Strauss of Climate Central, “I think this is really a first placing of human fingerprints on coastal floods and thousands of them.”

In a commentary appearing on Climate Central’s website, Strauss points out that MSL is more than just a function of greater water volume from melting ice. In some cases land is sinking (think Chesapeake Bay) while in other cases land is rising (think areas in the Canadian Arctic archipelago). This adds complexity to any attempt to understand MSL causes.

But the spike is such an aberration from the 27 previous centuries of accumulated data. Extended to the present day it represents a more than 15 centimeter (6 inch) rise and it is not slowing down.

Here are the raw numbers for United States’ coastal areas:

• 27 tide gauges studied looking at hourly water level records since 1950.
• total number of floods: 8,726.
• 5,809 or 2/3s ascribed to human caused MSL.
• in past decade (2005 to 2014) 75% of floods human caused.
• in some locations from Florida (see image below), San Diego to Seattle, and Honolulu, 90% of floods human caused.

These floods have overwhelmed and washed away beaches, damaged coastal roads, compromised stormwater and other municipal infrastructure, and polluted aquifers with seawater. They have come with high winds, storms and high tides, all weather acts. But because MSL is getting higher the weather impact is climate change induced.