Scientists today released evidence of historically unprecedented hurricane activity along the northeast coast of what would become the United States between about 800 to 1700 years ago, which was associated with warmer ocean temperatures similar to levels we may expect in coming centuries with climate change and ocean warming.
Geoscientists at the University of Massachusetts Amherst and Woods Hole Oceanographic Institute (WHOI) say new evidence they analyzed in sediment deposits from Cape Cod show that intense hurricanes, possibly more powerful than any storms New England has experienced in recorded history, frequently pounded the region from around 250 A.D. to about 1150.
Jon Woodruff and WHOI researcher Dana MacDonald, currently a visiting scholar at UMass Amherst, with lead author Jeff Donnelly of WHOI, say a warmer climate was associated with more intensity and frequent hurricanes on the U.S. East and Gulf coasts hundreds of years ago. They present a new record of sediment deposits in the current issue of Earth's Future, a journal of the American Geophysical Union.
Woodruff, MacDonald, Donnelly and colleagues report that 23 severe hurricanes hit the New England area between the years 250 A.D. and 1150, the equivalent of a severe storm on average about once every 40 years. Many were likely category 3 storms like Hurricane Katrina or category 4 storms like Hugo that would be catastrophic if they hit the region today, the authors add.
The study, the first to find evidence of historically unprecedented hurricane activity along the northeast coast, extends the hurricane record for the region by hundreds of years. Donnelly says the historical interval was "unlike what we've seen in the last few hundred years."
Late Holocene marine transgression and the drowning of a coastal forest: Lessons from the past, Cape Cod, Massachusetts, USA
Authors:
Maio et al
Abstract:
Extra-tropical storms in the spring of 2010 swept the New England coastline resulting in significant erosion along South Cape Beach, a barrier system located on Cape Cod, Massachusetts. The erosion revealed 111 subfossil stumps and a preserved peat outcrop. We hypothesize that the stumps represent an ancient Eastern Red cedar, Juniperus virginiana, stand growing in a back-barrier environment and drowned by episodic storm events and moderate rates of sea-level rise. Stumps, bivalves, and organic sediments, were radiocarbon dated using traditional and continuous-flow Atomic Mass Spectroscopy methods. Six sediment cores elucidated subsurface stratigraphy and environmental setting. Subfossil stumps ranged in age from 413 ± 80 to 1239 ± 53 calibrated years before present. We assume that this age represents the time at which the ancient trees were drowned by marine waters. Based on elevation and age, an 826 year rate of submergence was calculated at 0.73 mm/yr with an R2 value of 0.47. Core stratigraphy, microfossil assemblages, and radiocarbon ages indicate a dynamic barrier environment with frequent overwash and breaching events occurring during the past 500 years. Shoreline change analysis showed that between 1846 and 2008, the shoreline retreated landward by 70 m at a long-term rate of 0.43 m/yr. Future increases in the rate of sea-level rise, coupled with episodic storm events, will lead to the destruction of terrestrial environments at rate orders of magnitude greater than that during the time of the paleoforest.
In the 1970s, red spruce was the forest equivalent of a canary in the coal mine, signaling that acid rain was damaging forests and that some species, especially red spruce, were particularly sensitive to this human induced damage. In the course of studying the lingering effects of acid rain and whether trees stored less carbon as a result of winter injury, U.S. Forest Service and University of Vermont scientists came up with a surprising result – three decades later, the canary is feeling much better.
Decline in red spruce has been attributed to damage that trees sustain in winter, when foliage predisposed to injury by exposure to acid rain experiences freezing injury and dies. Paul Schaberg, a research plant physiologist with the U.S. Forest Service's Northern Research Station in Burlington, Vt., and partners studied red spruce trees in Vermont, New Hampshire and Massachusetts. They found that the influence of a single damaging winter injury event in 2003 continued to slow tree growth in New England for 3 years, longer than had been expected, and had a significant impact on carbon storage.
They also found something they did not expect.
