Study: Sea levels have not gone up this fast in 2,800 years or more

A new study led by Rutgers University about the rate of sea level rising was published this week and provides further evidence oceans are generally rising across the globe. Not only are they rising, but the speed at which the water is lifting along most shorelines is doing so faster than it has in the past 28 centuries, or 2,800 years, the study says.

According the paper, “the rate of global sea-level change in the 20th century (1.4 ± 0.2 mm/yr) was, with 95% probability, faster than during any century since at least 800 BCE.” Before this date the data isn’t as reliable, but this could be the fastest the seas have risen in even more millennium, we just don’t know how many as accurately as the past three.

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In the face of this new data, I thought it would be a good idea to provide some context for this and other studies about sea level change. In this blog post, I’m going to pose questions and then answer them.

Haven’t sea levels gone and up and down for thousands of years?
Absolutely, the oceans expand and contract with regularity. However, what this study looked at was how the added carbon dioxide from humans exacerbated the rise. The study took measurements from 24 locations around the world, along with measurements from 66 “tide gauges.” Using mathematical equations and computer simulations, these scientists compared a modeled world against the known data. These researches found, with a high degree of statistical certainty, the added non-naturally occurring gasses have given sea water rising a boost. While there’s a range in exactly how much human influence is present in the observed ocean level increase, it’s not zero.


You can’t predict the weather accurately, how can you predict the climate
This study looked at what’s occurred, and other studies explore what will occur in the future. However, the trend isn’t going away and the study shows the speed to be increasing. Two other studies published this week show sea levels potentially rising from 1 to 4 feet in the next 100 years. Carbon dioxide and other greenhouse gases are playing a role in our climate, and another way to think of it is this way: If a baseball player hits 80 home runs this season and breaks the all-time record is then found to be on steroids, how many of those hits are due to his extra help? Maybe he would have hit 50 without the juice, or even 70, but it’s highly unlikely he’d have gotten all 80. The atmosphere is on CO2 juice and while you can argue how much that’s playing into our climate, it’s not zero and anyone who puts that forth isn’t truthful, period.

Didn’t the oceans fall in some places and go up only a few inches in 100 years?
The oceans have actually fallen in places. The image below shows that where the Gulf Stream was present back in the 1990s sea level sank, this is because that river of warm water has shifted north. Not a good prospect. On average, ocean levels went up about 5.5 inches during the 20th century, and the speed they are rising is increasing. A boulder rolling down a hill might go a foot in the first second, but over time it will move a greater distance each second. The speed at which the oceans are rising is going up.

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I don’t have a home on the coast, this won’t affect me will it?
Society will continue to be impacted by rising seas. If you don’t have a home on the coast, it won’t matter because you taxes and insurance are going to increase to cover the cost of rebuilding or relocation. As flooding increases, the impact to all of us will be felt. Here’s a sobering statistic. This isn’t a prediction, rather what’s already occurred. From 1955 to 1964 the tide gauge at Annapolis, Maryland, measured 32 days of flooding. Fast forward to the decade from 2005 to 2014, that jumped to 394 days.

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I have bigger issues like my job, my kids, my house, what could I possibly do to stop the seas from rising?

The short answer is you are right, much of the sea level rise ahead is already baked into the system. The unknown variable is how much more the oceans are going to go up in the next century, not if they will go up. If this issue is important to you, then educate yourself on what’s true and what isn’t. Learn about the different scenarios ahead and the pluses and minuses of how we implement change to our current energy system.


Could the ocean start cooling soon?
The Atlantic ocean is currently in its warm phase of something called the multi-decadal oscillation. In the coming years, when this goes into the cooler phase the rate of sea level rise could slow or even perhaps reverse temporarily. This will need to be researched and modeled further.

Follow Dave Epstein on Twitter @growingwisdom

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