October 17, 2016 tidal flooding on a sunny day during the "king tides" in Brickell, Miami, FL that peaked at four feet MLLW. Photo: Wikimedia Commons CC BY-SA 4.0.

Sea Level Rise and High-Tide Flooding Outlook Make It to NOAA’s Climate Update

, climate scientist | June 21, 2017, 11:35 am EDT
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This post is a part of a series on The Paris Climate Agreement

On June 15, the National Oceanic and Atmospheric Administration (NOAA) held its Monthly Climate Update press conference, in which it releases the global temperature for the previous month. The big piece of information in this press conference usually comes on the very first slide of their presentation, which includes the measured global temperature for the month, and how much it deviates from the 20th century average of 58.7°F.

This month, however, something interesting happened: NOAA didn’t have the numbers, and mentioned right off the bat that they would be released the following Monday (June 19), hence this blog being published later than usual (for those of you who keep tally!).

Anyway, the month of May was the third warmest on record, at 1.49°F above the average, and the global average temperature for January–May 2017 was 1.66°F above the 20th century average of 55.5°F, making it the second highest January–May period in the 138-year record, behind only 2016 by 0.31°F.

Back to the press conference: it went through the usual motions of precipitation, temperature, and drought data, and future projections for those. But another thing was different: this month included a briefing on 2016 coastal flooding and sea level rise, and a future outlook for 2017.

NOAA 2017  high tide flood “outlook”

Sea levels continue to rise

NOAA and the National Weather Service have for a long time issued reports and alerts on flooding, especially related to coastal storms. They publish these updates when needed, on their website and through other communications means – we need them, and do use them whenever needed. We can always count on NOAA to keep us informed of weather and flood dangers.

What I am talking about here is different. While seasonally this press conference has included information about snow pack, or fires, or groundwater, in my memory it is the first time it includes a sea level rise report on flooding, specifically high-tide flooding – and an outlook for that.

According to William Sweet, NOAA oceanographer, flood frequency trends are increasing – and faster with time, meaning the rate of increase is itself increasing – due to sea level rise, and we have seen up to 1000% increase since the 1960’s.

In the briefing, Sweet explained that “seasonal high tides and minor wind events now cause high tide flooding in many locations”, and flooding in 2016 followed or surpassed the increasing trend – 130% higher on average compared to 1995. 2016 saw 2 locations break their records in number of coastal flood days: Charleston and Savannah, with 50 and 38 days respectively. Key West tied its record with 14 flood days. And the 2017 outlook calls for as many as 30 days above the trend in some East coast locations such as Lewes DE and Atlantic City NJ – in other words, this year is expected (for various reasons) to see flood frequencies greater than those expected with the sea level rise trend only.

So, in addition to reporting on record temperatures, precipitation and drought, and releasing their usual outlooks for those, NOAA briefed us on record flood. Even if that is not a regular feature, it has to perk up one’s ears.

Tidally driven coastal flooding is one of the most visible signs of sea level rise

As residents of Lewes, DE (and other locations along the US coast such as Miami Beach, FL and Norfolk, VA) say, “if you don’t think sea level rise exists, come visit us”.

Those are places that are currently dealing with sunny day flooding that disrupts their everyday lives to a point well beyond “nuisance” – which is what these types of floods used to be called.  People can’t get around whole neighborhoods, school buses cannot make their stops, and trash cannot be picked up when waters are high.

According to studies done by UCS (see US Military on the Frontlines, Encroaching Tides, Surviving and Thriving), the future, at least in terms of high-tide flooding, is not very bright for many locations along the East and Gulf coasts. Some areas that currently see about 10 flood events per year (such as Norfolk, VA) are projected to see as many as 280 by mid-century, and that with a conservative sea level rise scenario. This does not bode well for the millions of people who live on coastal communities, to say the least.

Future sea level rise scenarios offer a range of risks we must prepare for

As mentioned by Sweet, sea levels are rising faster since the end of last century, and NOAA even released a new set of sea level rise projections that will be used in the next National Climate Assessment (for a full review of the current sea level rise science, go here).

The new projections account for more, faster ice sheet loss, which is becoming increasingly plausible – both Arctic and Antarctic. And while we do not know how much of that ice will melt in the next years or decades, we know that some WILL melt. We must prepare for whatever range of sea level rise is plausible in the future.

Preparedness is at the heart of risk reduction. Lives and property can be saved with effective preparedness and pre-disaster mitigation measures. In order to prepare as best we can, we need the science coming from NOAA and the National Aeronautics and Space Administration (NASA), and we need the programs from the Federal Emergency Management Administration (FEMA) (more on these agencies, their programs, and their budgets here, here, and here). We cannot afford to lose funding for these agencies, as they are the ones minding our safety when it comes to sea level rise and other climate-related impacts. Can you say hurricane season?

While we cannot stop sea level rise right now – we are committed to a certain amount of rise simply because of the emissions already in the atmosphere – we can slow down the rate of rising in future years by reducing emissions of global warming gases now.

Internationally, the Paris Agreement is our big hope.  Here in the US it’s a different story: as the Trump administration seeks to leave that agreement, actions by state and local governments speak even louder – and will have results faster – than federal intentions. Let’s keep the momentum and stay safe, my friends!

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  • Ian Kidd

    “…we can slow down the rate of rising in future years by reducing emissions of global warming gases now.”
    This amounts to a continued acceleration of sea-level rise. To contain SLR, emissions must be negative!