How warm is warm?
Or, how to know when is warm not so surprising…
By Dr. George L. Jacobson, Maine State Climatologist
year has been interesting. We had a warm winter, a warm early
spring, a warm dry summer, and a rather wet September. Last
winter’s weather was unprecedented in modern history in two
ways: the warmth of November through May, and the lack of snow
after the middle of January. This map shows the temperature
departure from the long-term average for last January-February;
red areas were warmer than average and blue areas were colder
Some of the warmth can be attributed to El Nino. Despite
the apparent radical departure from normal in Maine, a warm
winter was expected, given that this was an El Nino year, when
warm ocean currents along the coast of Peru replace the usual
cold waters that typically upwell to the surface.
The figure below shows the departure from normal temperatures
over time; the warm El Nino events are in red.
The influence of El Nino conditions extend across the Pacific to
Indonesia and along the coast to Central and North America. Last
year, the El Nino warmth had British Columbia trying their
hardest to host the Winter Olympics in warm, rainy weather
instead of winter’s usual cold and snow.
Does El Nino explain all of the heat? Compared to all
winters of the past century, last year was among the top three
warmest. Ice-out on Maine lakes was earlier than in any recorded
year, and some golf courses even opened five weeks earlier than
usual! But when last winter is compared only to the nine most
recent El Nino years, it was just slightly warmer. The map on
the left shows the departure from normal winter temperatures
during previous El Nino events.
The 2009-2010 El Nino has ended, and the cycle has swung in the
other direction, toward La Nina. As shown by the map on the
right, La Nina winters are not significantly warmer or colder
than normal, and so this coming winter might be much more
“typical” (or what many would call a real Maine winter).
These weather patterns are just one aspect of long-term
variability in the Earth’s climate system. The variability is
sometimes cyclical, as in the case of El Nino-La Nina or even
ice ages, which occur about every 100,000 years. Short-term
cycles superimposed on long-term cycles like ice ages create
We certainly can’t say that last winter—or any one season—was
unusually warm only because of greenhouse gases; but it is also
quite possible that record heat is linked to the vast amount of
heat-trapping gases that have been added to the atmosphere in
recent decades. We won’t know for sure until enough time has
passed to give us a long-term perspective.
Model projections of what Maine might be like during coming
centuries indicate that the warm winter of 2009-2010 might well
be what is considered normal at the end of the century. Readers
who wish to learn more about changes that might be on the way
are invited to read Maine’s
Climate Future. In upcoming months we will delve further
into the causes of long-term and short-term variability in the
Earth’s weather and climate.
What do Maine’s coastal
communities need to safely weather more frequent and intense
By Alex Gray, Graduate Student,
University of Maine
Research Partners: Prof. Shaleen
Jain, Civil and Environmental Engineering & Climate Change
Institute and Esperanza Stancioff, Climate Change Educator,
UMaine Extension/Sea Grant
On April 16, 2007, one of the
largest spring storms in memory hit New England, sending 30-
foot waves crashing onto the coastline. The 2007 “Patriots’ Day
Storm” pushed many coastal communities beyond their ability to
cope with such extreme storms. Now, many cities and towns are
struggling to adapt current and future development projects to
withstand future storms of this magnitude, which are projected
to increase in both frequency and intensity.
Patriot’s Day Storm.
Photo by Lee Zipp (April 16, 2007, Biddeford, ME)
This spring, University of Maine
researchers met with municipal officials of Lincolnville and
Portland to discuss the barriers they face in preparing for the
effects of a changing climate. At both meetings, people said
reports like Maine’s Climate Future, while interesting (to those
who may have read it), contain too much uncertainty and lack
location-specific information for them to use in their
decision-making processes. As a result, researchers are now
interested in learning the types of information municipal
officials do use, especially when preparing their communities
for extreme weather conditions such as snow and ice storms,
storm surge, heavy rain, and high winds.
Another concern raised during
both meetings was that coastal communities experience different
types of damage during storms. In Lincolnville, when heavy rains
flood lakefront properties, the town
must ask the downstream town of Camden to open a dam in order to
lower water levels, but this usually causes flooding in Camden’s
downtown riverfront buildings and so the town is often reluctant
to open the dam. In Portland, downtown flooding is the result of
culverts that are too small to handle the runoff from severe
storms. The city wants to fix the inadequate culverts, but
limits of federal assistance further strain the limited
resources of municipalities.
Solutions for Lincolnville and
Portland need to be based on both the problems themselves
(rising lake water levels versus failing/inadequate culverts)
and the type of community being affected (small rural town
versus large urban city). In addition, information to solve
these problems needs to be specific to each community’s unique
characteristics in order to support their decision-making
In the Summer of 2010,
researchers from the University of Maine surveyed coastal
community officials to learn about problem areas and how they
are affected by snow and ice storms, storm surge, heavy rain,
and high winds. The research team is developing an “adaptation
atlas” based on the results of the survey, which will be used in
workshops and meetings with communities to discuss the solutions
and assets that will prepare them for a changing climate.
This project is funded through
the National Science Foundation Sustainability Solutions
Initiative at University of Maine George Mitchell Center.
from around Maine
Future: Coastal Vulnerability to Sea-Level Rise
a PDF of this fact sheet]
diverse coast is home to the majority of the state’s population.
It also attracts millions of visitors each year, sustaining
Maine’s valuable tourism industry. Working waterfronts support
fishing, shipbuilding, and related marine businesses. All of
these people and activities coexist at the fragile edge where
land meets sea.
hazards are not new to Maine. Coastal communities have been
dealing with storms and related flooding and erosion for
generations. However, an increasing sea level likely will
increase the impacts of these coastal events. If the rate of
sea-level rise exceeds the rate of sediment delivery to beaches,
dunes, and marshes, this could result in land loss and
instability of coastal ecosystems.
sheet presents the current state of knowledge on sea-level rise
and its impacts on Maine’s coast. This publication was created
in response to the need for more specific sea-level rise
information identified during the statewide climate change
adaptation stakeholder process [www.maine.gov/dep/oc/adapt/]
coordinated by the Department of Environmental Protection.
Additional fact sheets in the Maine’s Climate Future series are
under development. For more information, contact Catherine
Maine's Historic Coastlines
past, present, and future
Historically, sea-level changes
in Maine have been highly variable, as the land responded to the
growing and shrinking glacier of the last ice age. The shoreline
has ranged from as far inland as Medway and as far seaward as
Georges Bank, which was exposed as an island when sea level
reached its lowest elevation 12,500 years ago.
During the last 5,000 years, sea
level rose very slowly, a rate that allowed today’s beaches,
sand dunes, and marshes to form from the sediment carried by
rivers and re-worked by waves.
Modern-day measurements at a tide
gauge in Portland show that sea level has risen at a rate of
about two millimeters per year (mm/yr or 0.07 inches/year or 0.6
feet over a century). Although this doesn’t seem like much, it
is the highest rate in the last 5,000 years.
Tide-gauge records in Portland, Maine, show a sea-level
rise of 0.07 inches per year (1.77 mm/yr) since 1912
(Belknap 2008). The 2007
Intergovernmental Panel on Climate Change projection of
another one-foot rise in sea level by century’s end is
considered conservative by
Based on data released by the Intergovernmental Panel on
Climate Change in 2006, Maine adopted a planning
scenario in the Sand Dune Rules of a 50% chance of a
two-foot rise in sea level by 2100.
Why is the sea rising along
the Maine coast?
expansion: As the atmosphere gets warmer,
the ocean heats up and expands.
increase: The volume of the ocean increases
with water from melting glaciers and land-based
There is a slight regional subsidence of the
and the Maine coast
Sea-level rise is just one of
several factors that influence how the coast responds to
hazards; others include land use, geology, tides, currents, and
sediment volume. While scientists can’t always predict what will
happen to specific stretches of shoreline, they can make
reasonable predictions for certain coastal features.
Much of Maine’s outer coast is
steep and rocky, and resistant to rising water levels. About 46%
of the coast—over 1,400 miles—is comprised of bluffs
formed from soft, loose sediment. Future bluff stability will
vary based on the frequency of wave or storm attack, the
exposure of the bluff to storm waves, and the ability of the
bluff to lose sediment at a rate that would maintain a
protective wetland or marsh in front of it. These features will
continue to erode and move landward in the face of rising sea
levels. The Maine Geological Survey and the Maine State Planning
Office analyzed the distribution of coastal bluffs, the severity
of erosion, and the extent of shoreline engineering along the
coast, and found that at least 40% of Maine’s coast is
vulnerable to increased erosion at higher sea levels.
Yellow and Greens
MGS Coastal Bluff Map
MGS Coastal Landslide Hazard Map
For more details
see the MGS Web
Bluff response to sea-level
rise and storms
Modified from Kelley and Kelley,
Tidal flats, Salt Marshes, and
Tidal flats and salt marshes
exist in a very narrow zone between the tides, and are probably
the most susceptible habitats to sea-level rise in Maine. Small
changes in sea level can change the pattern and frequency of
tidal flooding, resulting in major changes in the type and
extent of flats and marshes.
Tidal flats may be flooded too
frequently to serve the millions of hungry shorebirds that visit
on their annual migrations. In other areas, eroded sediment
could smother commercially important shellfish habitat.
Infrequently flooded “high” salt
marsh environments, particularly in southern and mid-coast
Maine, could revert to “low” salt marsh habitats, or become open
water where development or steep slopes block their landward
migration. If sedimentation rates can keep up with sea-level
rise, the marsh systems may maintain themselves for some time.
It is likely that the overall structure of the marsh will
change to a more dynamic mixed- or low-marsh dominated
system, and some marshes will be lost altogether.
Freshwater wetlands and bogs are
often located adjacent to tidal wetlands. Sometimes only a
slight difference in topography separates the two, and as sea
level rises, salt marshes can expand into previously freshwater
marshes. Salt water that creeps into freshwater bogs and marshes
can kill plants, hastening land loss.
This air photo shows a tidal flat, salt marsh (light color) and
freshwater bog (dark color) in
Jonesport. Marine environments have the potential to rapidly
replace freshwater systems with rising sea level.
Beaches and Dunes
Although they only make up about
2% or roughly 70 miles of Maine’s coastline, beaches and sand
dunes serve as the primary means of shoreline protection along
the sandy coast. Beaches and dunes also experience some of the
most intense development pressure. Typically, beaches and dunes
respond to rising seas and coastal storms through the processes
of overwash, when high tides and storm surge wash over the beach
and break through the dunes, depositing sand behind the dune or
carrying sand back into the sea. Slowly, the entire beach system
rolls over itself and migrates landward (a process called
“transgression”). The response of beaches to sea-level rise
depends on the relationship of the
sedimentation rate to the rate of sea-level rise; and also
whether or not the beach or dune has the ability to migrate
inland. Beaches that have limited sediment supplies or no room
to migrate will likely erode in a much shorter period of time
and could potentially disappear. Tree stumps on the beach and
mudflats at Scarborough’s Ferry Beach are evidence of beach and
Some coastal residents get their
drinking water from wells drilled into fractured bedrock
aquifers that are susceptible to saltwater intrusion. With
increased sea levels, saltwater contamination of drinking water
could become more widespread and problematic.
The majority of Maine’s
population resides in the coastal zone. Development and related
infrastructure—roads, water and sewage treatment facilities,
piers and homes—are damaged or impaired by flooding and storm
surges. Increased storm frequency and intensity, combined with
rising sea level, makes all storms more damaging, with serious
economic and ecosystem consequences to the region and state.
Economists Charles Colgan and Sam Merrill of the University of
Southern Maine found that in York County alone, over 260
businesses representing $41.6 million in wages are at risk from
coastal flooding and the resulting property destruction and
higher insurance costs.
change and building a resilient coast
One way that
Maine has already acted to address the threat of sea-level rise
is through the Natural Resources Protection Act’s Sand Dune
Rules and shoreland zoning program. These rules anticipate
future shoreline changes from a two-foot rise in sea level by
2100, based on the best data available at the time of
rulemaking. This scenario is a conservative estimate, because
current sea-level rise projections do not account for potential
freshwater input from the melting of the Greenland or Antarctic
ice sheets. The Sand Dune Rules allow communities to plan for
sea-level rise; in reality, however, coastal managers are
already dealing with many of the problems expected to result
from sea-level rise, storms, and flooding. But they need tools
to identify locations and properties that are vulnerable to
inundation, so they can make decisions about where and when to
build piers, roads, houses, wastewater treatment plants, and
other infrastructure. For example, current UMaine research is
beginning to map freshwater wetlands at risk from rising sea
level and to predict their rate(s) of transformation. In the
past, people responded to the threat of erosion by building
seawalls, bulkheads, and other barriers; at least 152 miles of
bluffs, or about 5% of the coast, are armored with these “hard”
structures. Today, managers recommend “soft” engineering
structures that protect coastal property without worsening
erosion elsewhere. Taking a neighborhood or community approach,
rather than protecting individual properties, benefits everyone.
sheet was produced as a supplement to Maine’s Climate Future,
published in 2009 by the University of Maine. For more
information on that report and research at the Climate Change
latest information about climate change in Maine, and for a PDF
of this document, see
resources about building a resilient coast are available at
Catherine Schmitt, Maine Sea Grant
Designed by Kathlyn Tenga-Gonzalez, Maine Sea Grant
With contribution and review by Esperanza Stancioff, University
of Maine Cooperative Extension and Maine Sea Grant; Peter A.
Slovinsky and Stephen Dickson, Maine Geological Survey; Joseph
Kelley and George Jacobson, University of Maine; and Elizabeth
Hertz, Maine Coastal Program.