New England Hurricanes, the forecast every time

12 11 2012

Kevin Anchukaitis

Let me start my first post here at Strange Weather by thanking Julien for the opportunity to join him here at his blog. I’ve been studiously preparing by listening to lots of Tom Waits albums, and although I hadn’t intended for my first post to be about hurricanes in the northeastern United States, some strange weather intervened.

I’m a recent arrival to the Massachusetts coast and now a scientist at the Woods Hole Oceanographic Institution, after spending the previous several years in New York City. While Superstorm Sandy, née Hurricane Sandy, was still several days from landfall in New Jersey, though, the region’s history of deadly hurricanes was already in the front of my mind. In August of 1991 Hurricane Bob scored a direct hit on Falmouth on Cape Cod in Massachusetts — my new home. At barbeques and gatherings this summer, my immediate neighbors were telling their stories of Bob’s “furious” landfall, the wind, the snapping trees, the storm surge, the flooding — and the long aftermath without power. So as Sandy lined up for her run at New England at the end of October, I admit I was somewhat nervously eyeing the tall but spindly locust trees near my house.

New England is not without a reason to keep one eye on the tropics in the late summer and autumn. Besides Bob, the New England Hurricane of 1938, the Great Atlantic Hurricane of 1944, Hurricane Carol in 1954, and Hurricane Donna in 1960. Wikipedia has a list of New England hurricanes. In 1821, a hurricane passed directly over New York City, resulting in 13 feet of storm surge and causing the East River to flow across lower Manhattan south of Canal Street. Yet another reason to be wary about hurricanes in New England lies in the mud and sand of the coastal marshes up and down the New England coast, several of which are disconcertingly within walking distance of my new home. These environments preserve a long record of storm activity in coastal New England going back hundreds or thousands of years.

Jeff Donnelly is a colleague of mine at Woods Hole Oceanographic Institution and one of the world’s experts in paleotempestology (Andrew Alden has a nice write-up on this science, here) — the study of past major storm activity from geological or biological evidence. Jeff uses sediments in coastal environments like marshes to identify and date past storms, but others have also used stable isotopes in tree rings, corals, and cave deposits, as well as historical records.

Marsh sediments from across New England tell a story of past hurricane strikes in the region, some clearly quite large. These environments record the passage of strong storms in the overwash deposits of sand that flood over their barrier with the sea during high waves and storm surges. Shore Drive in Falmouth is just such a barrier, and Sandy demonstrated quite clearly what an overwash deposit on its way to a backbarrier marsh looks like.

In a 2001 paper in the journal Geology, Jeff Donnelly and colleagues used multiple sediment cores extracted from a backbarrier march at Whale Beach, New Jersey, located between Ocean City and Sea Isle City, just to the south of Atlantic City, and close to where Hurricane Sandy made landfall, to reconstruct a history of beach overwash. They found deposits of sand associated with a 1962 nor’easter and another strong storm which they believed was the 1821 Hurricane. They dated a third deposit, thicker than the 1821 sand layer and probably related to an intense hurricane, to between 1278 and 1438 CE. In their article they note that the Whale Beach record suggests an annual landfall probability of 0.3%.

In a 2004 paper in Marine Geology, Donnelly and his team again looked at overwash deposits in New Jersey, this time from Brigantine, just to the north of Atlantic City. Here again they identified a layer of sand in the backbarrier marsh likely corresponding to the 1821 hurricane. They also dated large sand layers to the period between 550 – 1400 CE, which might correspond with the 13th or 14th century event identified at Whale Beach.

Donnelly et al. 2004, Marine Geology

Original caption from Donnelly et al. 2004, Figure 7: Cross-section of Transect 2 at Brigantine. ( p ) Location of radiocarbon-dated samples (see Table 1). Horizontal axis begins at the barrier/marsh boundary. The vertical datum is the elevation of the barrier/marsh interface (approximately mean highest high water).

Further to the east, in another 2001 paper Donnelly and his team used sediment cores from Succotash Marsh (near the fabulous Matunuck Oyster Bar near Point Judith in Rhode Island) to date hurricane strikes to known events in 1938 and 1954, as well as 1815 and the 1630s. Two other overwash deposits were dated to 1295-1407 and 1404-1446 CE. Donnelly and coauthors concluded that “at least seven hurricanes of intensity sufficient to produce storm surge capable of overtopping the barrier beach at Succotash Marsh have made landfall in southern New England in the past 700 yr”

One more, closer to home: In 2009, Anni Madsen and her coauthors (including Donnelly) published dates on hurricane deposits in Little Sippewissett Marsh in Falmouth, Cape Cod, Massachusetts, using optically stimulated luminescence (OSL) dating. This particular core shows a number of overwash deposits over the last 600 years, including probably Hurricane Bob and the 1976 Groundhog Day storm, but is also indicative of some of the difficulties and uncertainties in using backbarrier marshes to reconstruct hurricane strikes: Little Sippewissett Marsh doesn’t have sand layers that obviously date to recorded storms in 1938, 1944, 1954, 1815 and 1635, which include some of the largest to hit this region. Uncertainties arise from, amongst other things: a single core may not record all the storms at a site, storms themselves alter the height of the barrier and inlet channels, dating of events comes with analytical and depositional uncertainty, and in New England strong storms could be hurricanes or nor’easters.

Madsen et al. 2009, Geomorphology

Location of Little Sippewissett March, showing 19th and 20th century storm tracks across the region, from Madsen et al., A chronology of hurricane landfalls at Little Sippewissett Marsh, Massachusetts, USA, using optical dating, Geomorphology 109 (2009) 36–45, 2009

On Dot Earth, Andy Revkin has pointed toward his articles on Donnelly’s Caribbean research, as well as a 2002 paper by Anders Noren on millennium-scale storminess in the northeastern United States.

Bringing us back to Sandy, what does the history and geology of New England hurricanes tell us? There is evidence from all along the coast that powerful storms do occasionally make landfall in the region. The evidence from Whale Beach in New Jersey, near to where Sandy came ashore, records the very strong 1821 hurricane as well as another likely event in the 13th or 14th century. Other strong storms have hit the New England coast at other times in the past millennium. A 2002 article from the Woods Hole Oceanographic Institution quotes Donnelly:

“Most people have short memories,” says Donnelly. In fact, it is estimated that three-quarters of the population of the northeastern US has never experienced a hurricane. Donnelly’s research provides evidence to be heeded. “The geologic record shows that these great events do occur,” he says. “We need to make people aware that it can happen again. We’ve got to have better evacuation plans and we need to equip people to react to a big storm.”

I’m so far agnostic on the precise influence of human-caused climate changes on the track and characteristics of Sandy. The process of sorting out the influence of natural variability from the human-influence on this particular storm has just begun. As Justin Gillis notes in the New York Times Green Blog:

Some [climate scientists] are already offering preliminary speculations, true, but a detailed understanding of the anatomy and causes of the storm will take months, at least. In past major climate events, like the Russian heat wave and Pakistani floods of 2010, thorough analysis has taken years — and still failed to produce unanimity about the causes.

The influence of rising sea levels, particularly along the east coast of North America, no doubt has to be factored into understanding current and future storm surges. But what the geological and historical record indicate is that even in the absence of a human-influence on the strength, track, or magnitude of tropical storms, we would still need to be prepared for destructive coastal storms to strike areas of high population and considerable infrastructure. Paleoclimatology — in this case, paleotempestology — nearly always provides us with evidence of an even greater range and diversity of behavior of the climate system then we’ve witnessed over the relatively short period of instrumental observations, and gives an idea of some of the events — droughts, floods, and storms — that we need to keep in mind when figuring out how to build resilient communities.

Advertisements




Strange Weather gains new Strange Weatherman

12 11 2012

Dear reader,

it is with great pleasure that I welcome to this blog my esteemed friend, colleague, and lobster-slayer  Kevin Anchukaitis.

Kevin Anchukaitis coring a tree in a particularly scenic location

Kevin is a fellow paleoclimatologist with origins in dendroclimatology (using trees to infer past climate conditions), a long record of field work in some of the world’s most amazing places (Bhutan, Vietnam, Cambodia, Guatemala), an equally long record of great publications, a healthy obsession with good code, a peerless taste for good wine and an even better writing style, with which he has previously graced the New York Times “Scientist at Work” blog.  It is a privilege and an honor to welcome him as a fellow Strange Weatherman, and I trust you will enjoy his first post as much as I did. Let’s hope for many more to come!

Happy reading,

Julien

PS: it should be said that  Strange Weather science is gender-blind, so we will heartily welcome Weatherwomen too. And this reminds us that one should invent a less sexist term than “weatherman” to designate the TV meteorologists whose job it is to gesticulate in front of a blue screen while blurting out technical terms about the weather.





Happy Waits Year

7 01 2008

It is only a few days into this new year : a perfectly opportune moment to celebrate its inception. And to wish all my dear readers (the whole half dozen of them) a great coming year.

This one started on blissfully auspicious terms for me, so i’ll stick to one wish : see Tom Waits live sometime soon. Because, as much a this blog is about climate, let’s face it : there are more important things in life – like Tom Waits.

I am now in New York, and how fitting is it i stumbled upon this interview today ?

in which one can hear what instantly became my favorite NYC quote :

Q : Tom, how would you describe New York City ?
A : Well, it’s like being on a ship, you know. And the water is on fire…

I have a direct view on the Empire State Mast as we speak, looking down on the sea of freakers that is Union Square, and i have to say he’s damn right. As always.

Anyway, more to the point of this blog, which is named after a song from the master : i have taken up to documenting Mr Waits’ meteorological musings. I engage all the Tom Waits fans around here (i know there are a few) to pop in and point out all those that have escaped my attention.

So far i counted :

Blue Skies [The Early Years] (1971)

Diamonds on my windshield [The heart of Saturday night] (1974)

Shiver me timbers [The heart of Saturday night] (1974)

(thanks to Scotopia)

Emotional Weather Report [Nighthawks at the diner] (1975)

Rain dogs [Rain Dogs] (1985)

Cold Cold Ground [Frank’s Wild Years] (1987)

Strange Weather [Big Time] (1988)

A Little Rain [ Bone Machine] (1992)

November [The Black Rider] (1993)

There’s only Alice [Alice] (2002)
(thanks to ICE for pointing it out)

Make it Rain [Real Gone] (2004)

So I wish you all a great 2008. Listen to Tom Waits, keep the carbon footprint low, do good whenever you can and the world will be a better place.