The Frankentides are Coming — US East Coast to See Season of Flooding From El Nino + Sea Level Rise This Winter

According to preliminary reports from NOAA, this Fall, Winter and Spring will likely bring an abnormal number of flooding tides to the US East Coast. These emperor and king tides are primarily driven by sea level rise — a knock on impact of human-forced warming. But during an El Nino year, as with this year, wind patterns along the East Coast tend to drive tides even higher. At El Nino times, lows tend to form off the US East Coast. These lows tend to generate a consistent northeasterly wind that pushes against the northward flow of the Gulf Stream. This action reduces the Gulf Stream’s ability to pull water away from our shores, and some of that water rebounds against the US East Coast.

During a normal year, this would somewhat increase the height of East Coast tides. But, due to Greenland melt pumping fresh water into the North Atlantic, the heat and salt driven circulation that generates the Gulf Stream is weakening (See Signs of Gulf Stream Weakening). So this year’s series of El Nino lows are forming over seas that are already rebounding against the US East Coast. Forming in seas that have already risen due to the melting of glaciers around the world. A NOAA press release from September notes that recent findings:

“…build upon two nuisance flooding reports issued last year led by NOAA scientists William Sweet and John Marra. The previously published reports show coastal communities in the United States have experienced a rapid growth in the frequency of nuisance tidal flooding, a 300 to 925 percent increase since the 1960s, and will likely cross inundation tipping points in the coming decades as tides become higher with sea level rise”

“We know that nuisance flooding is happening more often because of rising sea levels, but it is important to recognize that weather and ocean patterns brought on by El Niño can compound this trend,” said Sweet.”

image

(The 2015 El Nino — the year sea level rise came home to roost for the US East Coast. NOAA predicts a significant increase in the number of tidal flooding events all up and down the East Coast due to a combination of El Nino and impacts related to human-forced climate change. Image source: NOAA.)

It is due to this confluence of factors that we are likely to see some pretty extreme flooding tides anywhere from Miami to Maine. Flooding tides that, according to NOAA, are 33 to 125 percent more frequent than even the recently elevated trend. Tides that, as we have already seen (see below) are much higher than during any typical year — El Nino or no. Such impacts are likely to occur even without the influence of strong Nor’easters. But for the East Coast, Nor’easters and El Nino tend to go hand in hand.

So it’s shaping up to be a flooding season. One that wouldn’t have happened before. One brought on by the impacts of a human-forced warming. And one that is but a harbinger of more flooding to come.

Fall of 2015 Already Seeing Substantial Inundation Events

Over the past few weeks, a freak series of high tides inundated large sections of the U.S. East Coast. In Charleston, South Carolina, on October 27, a high tide peaked at 8.67 feet above mean low water. That’s the highest tide for Charleston since Hurricane Hugo roared ashore in 1989. But in this case, there was no category 4 hurricane. Just a ridiculous amount of water flooding in from the ocean. In Savannah, Georgia tides ran 10.43 feet above mean low water on the same day. Again, no storm, just a rising ocean flooding out roadways and inundating homes and neighborhoods. Only a couple of days later, on October 29th, large sections of Boston Harbor flooded under perfectly blue skies.

Tybee Flood

(Flooding, primarily due to sea level rise and an extreme high tide, inundates coastal lands near Tybee, Georgia on October 27th. It was the worst flooding since a category 2 hurricane hit the region in 1935. This year, there was no hurricane. Just sea level rise caused by human forced warming combined with the typical impacts of El Nino on East Coast tides. Image source: Blame Sea Level Rise.)

For stormless days, this level of tidal flooding is unprecedented. It’s a validation, just one month later, of NOAA predictions. If anything, these tides were even higher than expected. Tides influenced by sea level rise, glacial melt in Greenland, and by an El Nino driven shift in wind patterns. Had these tides coincided with a strong Nor’easter or a Hurricane, what we’d be looking at is a level of flooding that would almost certainly have exceeded the worst such events ever to strike the US East Coast. In effect, what we see is that sea level rise due to human forced warming of the globe is starting to have a greater and greater impact on these shores. An awful and early impact that will only worsen as time and human warming progress.

A Global Problem Set Off By Human Warming

Over the longer term, there are a lot of people in the path of this global trend of rising waters. In the US alone, more than 143 million people live in coastal communities. And the seas, due to human-forced warming are on the rise.

But its not just the US East Coast that’s in trouble. Practically everywhere, seas are rising. Global temperature increases of about 1 degrees Celsius above 1880s values are causing the oceans to thermally expand. In addition, glacial melt from mountain systems, Greenland and Antarctica is contributing ever-increasing volumes of water to the global ocean, forcing on the waters’ rise at ever-increasing rates. Currently, long term trends indicate a 3.3 millimeter per year average increase in the height of the world’s oceans (from 1993 to present). And as the world starts to close in on 2 degrees Celsius above 1880s averages, the pace of that rise is expected to ramp up and up.

Already, current sea level rise presents increasing problems to coastal regions across the globe. Much of the impacts we presently see are due to salt water invasion of low lying regions, nuisance flooding events, the amplification of storm driven tides, and increasing instances of what are now called king and emperor tides. Adding complexity to this global warming related problem is the fact that seas do not rise in a uniform manner. This lack of global uniformity of sea level rise results from gravity’s affects on the displacement of waters and from the influence of water outflows from glaciers on ocean currents. As a result, global sea level rise can generate hot spots where rates of rise are significantly in excess of the global average.

US East Coast as Sea Level Rise Hot Spot

Global Sea Surface Height Anomaly NOAA

(Over the past few months, a bulge of water more than 1.3 feet higher than the 1981 to 2013 global average has expanded off the US East Coast. This bulge is driven by a combination of Gulf Stream slowdown due to Greenland melt, overall sea level rise due to global warming, and due to an El Nino pattern that drives northeasterly winds off the US East Coast. This year, this extreme bulge is expected to bring on a significant increase in the number of flooding tides. Tides that could be compounded by the effects of strong nor’easters that tend to be generated during El Nino years. Image source: NOAA CPC.)

Unfortunately, as we have seen above, the impacts of gravity rebound and current changes related to glacial melt put the East Coast of the United States directly in the path of a significant rise in ocean water. Specifically, Greenland melt results in a slowing down of the Gulf Stream. And it is the northward draw of the Gulf Stream that pulls about 3 feet worth of sea level rise away from the US East Coast. Slow down the Gulf Stream by dumping cold water into the North Atlantic and you can get about a foot of sea level increase off the US East Coast. Stop it completely and all that 3 feet of water comes sloshing back. Add any global sea level rise due to ocean warming and glacial melt on top of that and you can see why the US East Coast can quickly get into trouble.

All in all, scientists expect sea level rise for the US East Coast to be nearly double the global average predicted for this Century. And what this means is that more and more coastal flooding is on the way.

Links:

The State Did Warn Us

Can’t Get Home? Blame Sea Level Rise

NOAA: El Nino May Accelerate Nuisance Flooding

Melting Ice in West Antarctica Could Raise Seas by 3 Meters

Historic Tides From Sea Level Rise and Supermoon Flood US East Coast

NOAA CPC

Hat Tip to Greg

Hat Tip to Colorado Bob

Hat Tip to DT Lange

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For Miami, Sea Level Rise Has Already Gone Exponential

(AP story showing the effects of 9 inches of sea level rise over the last 100 years. What the story doesn’t mention is that half of this sea level rise has occurred within the past 16 years and fully a third of it has occurred within the past 5 years. Video source: Associated Press.)

This week, Miami is scrambling to deal with a flooding emergency.

But the cause is not the looming approach of a major hurricane or even a powerful tropical storm. The flood emergency for the coming three days is simply a seasonal astronomical high tide. Something they are now calling a King Tide. A condition that arises due to solar and lunar alignment a few times every year. A gravitational flux that pushes high tides another foot or so above the normal range.

Decades or even years ago, astronomical high tide wasn’t so much of a problem for Miami. Now, it means flooded roads and runways. It means salt water backing up through city drainage and municipal water systems. It means sea walls over-topped. It means lawns, properties and businesses covered in water.

The crisis is so serious that the city has already allocated more than 400 million dollars to deal with the problem. And this week, crews and flood prevention planners are scrambling to face the rising seas.

Rapidly Rising Waters

 

Miami Sea Level Trend

(Peak high tide trend from 1998 through 2014 shows sea levels rose by 4.3 inches over the past 16 years with most of the rise occurring since 2008. Image source: Dr. Zhaohua Wu, FSU)

At issue is the fact that Miami is facing a climate change driven sea level rise that is in the process of going exponential. A ramping rate of water rise that is being driven by a combination of glacial melt, ocean expansion due to warming, a backing up of the Gulf Stream which is raising waters all along the Eastern Seaboard, and a continuation of land subsistence in South Florida due to a variety of factors.

From 1914 through 1998, sea levels rose by an average of 0.06 inches per year — a rate that was barely noticeable to residents and city planners alike. But from 1998 to 2009 the pace increased to a more troubling 0.14 inches per year. And from 2009 to the present year the pace again jumped to a terrifying 0.67 inches per year.

An exponential rate of sea level rise that, in the past year alone, raised Miami’s surrounding ocean waters by 0.86 inches. Should the observed sea level rise over recent years continue, Miami will be facing 6-9 feet of additional water by the end of this century and not the 3-4 feet currently predicted.

Vulnerable Miami, South Florida

Miami is particularly vulnerable to such rapid rates of sea level rise for a couple of reasons. First, most of Miami is less than four feet above 20th Century sea levels. So even moderate rates of sea level rise put major portions of the city under water. Second, the city sits on porous limestone. The rock, riddled with holes, leaks like a sieve. So building sea walls won’t help Miami much as water will simply rise up through the rocks themselves.

Because Miami is so low-lying and surrounded on almost all sides by water, it is often seen as one of the most vulnerable cities to human-driven climate change. However, the geological conditions are not unique to Miami and remain a problem for almost all Florida cities. The porous limestone is a feature of the entire Florida Peninsula. So the problems Miami is facing now will become problems for hundreds of cities and communities up the coast and in more central regions of the state as well.

At most immediate risk is all of South Flordia. Miami-Dade and Broward Counties have about half of their residents living below the 4 foot above sea level line. Collier and Monroe counties also boast very large populations within just 4 feet of already rapidly rising seas. Such a rise would generate inland water upwelling throughout much of south Florida and the Everglades even as many coastal regions faced inundation. Small, low-lying islands and barrier zones would be swallowed by the sea or broken by incursions through weak points. The mangroves, already in retreat, would be swiftly beaten back. Inland lakes, invaded by higher pressure salt water from below, would also rise.

FinalUnifiedSLRProjection

(Sea level rise observations and projections through 2060 for Key West. Note that observations end at 2009 and that the tidal gauges have recorded a 3 inch sea level rise from 2009 through 2014 for Miami — already hitting the bottom range of expected sea level rise by 2030. Image source: Southeast Florida Regional Climate Change Compact Page.)

As an example, seasonal high tides are already having an effect on the Delray Beach region that is starkly similar to problems now plainly visible in Miami. In the historic Marina neighborhood, water bubbles up from storm drains and spills over the banks of the Intracoastal Waterway into streets.

Charle Dortch, a resident for 17 years said in a recent interview with the Sun Sentinel:

“It’s progressively getting worse. The water is coming up the roadway right into people’s front yards. It’s flooding the parking area. It’s coming up higher and higher every year.”

Links:

Water, Water Everywhere: Sea Level Rise in Miami

Southeast Florida Regional Climate Change Compact Page

Southwest Florida Governments Not Planning For Sea Level Rise

The Ocean is Already Higher

In Miami, The King Tide is Coming

Associated Press

Sea Level Rise: Everglades

Florida and Rising Seas

Dr. Zhaohua Wu, FSU

(Hat Tip to TodaysGuestIs)

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