Sunday, May 6, 2012

Comments on Climate Change

Many wonderful things happen through chance encounters. A few weeks ago, I spoke with a delightful couple when working as the whale watch naturalist aboard Captain John Boats. Through this conversation, I learned that the gentleman was a coastal scientist who studies climate change and its impact to the Cape Cod area. Dr. Williams was kind enough to send me this wonderful summary and overview on climate change and I wanted to share it with all our members.  Best, Krill


An example of Massachusetts’ future. Falmouth’s West Falmouth harbor dock and roadway are flooded by routine astronomical spring high tides as a result of sea level rise, an impact of our changing climate. Photograph taken on 5 November 2010, courtesy of Betsy Gladfelter.

Climate Change and Impacts to the Massachusetts Coast
S. Jeffress Williams, Coastal Scientist

Cape Cod, the Islands, and much of the Massachusetts coast are landforms deposited from the massive glaciers that covered much of North America until 15,000 years ago when the climate was colder than present and sea level was 400 feet lower. Since the end of the last glacial period, the climate has warmed and sea level has risen due to natural forces. Dynamic coastal processes have since modified the shorelines by erosion and accretion of sandy sediments. The record-breaking mild winter of 2011-12 over New England may be an indicator of global warming and a changing climate, but such seasonal trends are part of the weather cycle and could instead be a natural short-term aberration. The terms weather and climate are easily confused by the public. 

Weather is the short term state of the atmosphere at a specific location. Climate describes the longer term cumulative weather record-decades to centuries- based on observations and measurements and is the ‘average’ of the highly variable weather cycles. Climate is driven by many factors which interact with both positive and negative ‘climate feedbacks’ where primary factors interact in complex ways to produce secondary changes. Feedbacks can either enhance or diminish changes to climate. For example melting of Arctic sea ice and more open ocean area is a positive feedback while volcanic ash eruptions high in the atmosphere can be a negative feedback leading to temporary atmospheric cooling.

The scientific record based on many decades of data and well established scientific understanding of climate processes, however, is unequivocal and scientific consensus is strong that Earth’s climate on average is warming globally with a consequence that many dramatic changes are taking place on scales ranging from local to regional to global. The record warmth of 2011 combined with the warmest decade in recorded history, 1999 to 2009, is further evidence the climate is changing. Climate is largely determined by “greenhouse gas” concentrations in the atmosphere that absorb solar heat and produce the “Greenhouse Effect”.  


The main greenhouse gases are methane, nitrous oxide, fluorocarbons, water vapor, and carbon dioxide (CO2) and optimum amounts are vital for life on Earth. Carbon dioxide is not the most absorbent gas but it is very abundant and can remain in the atmosphere for a century or longer. World-wide, CO2 levels have varied greatly over time. During past glacial periods of cold climates, the amount of CO2 in the atmosphere was about 180 parts per million (ppm). During interglacial warm periods, CO2 was about 280 ppm. Today the concentration is 390 ppm, a 30% rise since the Industrial Revolution in the mid-1800s and higher than any time in Earth’s history for the past 15 million years.

In Massachusetts, air temperatures have increased almost 2 degrees F in the past 40 years and surface ocean temperatures have gone up even more. Evidence suggests that Earth’s average surface temperature today is higher than in more than the past 1,300 years. Sea level has risen almost one foot over the past century and the rate of rise has increased 50% since 1990. Coastal erosion and loss of sandy beaches has also increased. Many roads, dock areas, and lots are routinely flooded several times a year corresponding with spring “moon” high tides. And these rates of change with erosion and increased frequency of flooding are increasing and likely to continue for the rest of this century and for hundreds of years into the future. This conclusion is based on numerous independent and highly credible studies by climate and earth scientists in the U.S. and world-wide. Several of these leading scientists live and work at the research institutions in Massachusetts.

This global warming being measured and observed is greater and faster than can be ascribed solely to natural processes and is due mostly to a dramatic increase in CO2 released from our burning of fossil fuels (coal, oil, gas, wood) since the start of the Industrial Revolution, as well as the explosive growth of the world’s population which has reached 7 billion. These increases in CO2 and other gases in Earth’s atmosphere are enhancing the Greenhouse Effect where the Sun’s incoming rays are trapped by the atmosphere and heat absorbed. A challenge for the public is that these gases are invisible and the gradual buildup is not obvious; however, gas increases are readily measured by instruments around the globe. Other factors such as volcanic eruptions and variations in solar output can also affect climate, but none are driving the warming that has been documented over the past century.

The global warming taking place is uneven and highly variable but it’s already having dramatic effects on ocean and continental ecosystems and environments. And the effects are going to increase in frequency and magnitude in decades ahead, especially for coastal and low-lying regions such as Cape Cod and coastal communities.

Massachusetts is experiencing climate change as evidenced by:
  • ·      Increase in air and ocean surface temperature
  • ·      Increase in rainfall intensity; more variability in rain and drought patterns
  • ·      Increase in the rate of sea level rise
  • ·      Increase in coastal erosion and loss of beaches, dunes, and wetlands
  • ·      Increased ocean acidification
Unfortunately, climate change has been denied and dismissed as fraud and conspiracy by some with self-serving interests, but those are opinions not based on objective factual evidence. In many cases these are lies intended to mislead and confuse the public about the true nature of climate change and its causes.

Climate change poses a serious and immediate threat to the economy, natural resources and the environment, and public health. All regions of the U.S. are vulnerable to varying degrees, but low-lying coastal areas and communities that depend on tourist revenue and taxes on property along the shore are particularly at high risk due to sea level rise, increased erosion, more frequent tidal flooding, and increase in storm activity.

A few key messages about climate change are as follows:
  • A dynamic and changing global climate has long been part of a natural Earth cycle; however, human activities, particularly carbon emissions into the air since the mid-1800s have increased global warming causing a variety of well documented and pervasive environmental change. These changes are increasing risk of hardship and hazards to humans, especially along coasts and low-lying regions.
  • Sea level rise, in concert with storms and geophysical conditions, is a main driver of coastal erosion and shoreline retreat. Sea level has risen one foot over the past century; rates have increased 50% since 1990, and global average sea level is expected to rise as much as 3 to 5 feet by the end of this century. Higher rates of warming and ice sheet melting and changes in wind and ocean circulation patterns may further increase the projected rise in sea level.

  • The probability of continued global warming and sea level rise is high and planning for long-term strategic adaptation to these changes is needed now. Plans should be based on credible science, engineering, and economics and consider all costs and benefits to strive toward sustainable coasts, coasts that maintain natural processes but also are able to accommodate human uses.
In closing, the Massachusetts coast is already experiencing many effects of climate change and more dramatic impacts are coming. Some of the more immediate impacts are erosion of sandy beaches, increased tidal flooding and overwash of low-elevation areas and failure of septic systems and fresh water wells due to salt-water intrusion. Mitigation is needed to reduce CO2 emissions and well established adaptations measures such as beach nourishment, elevation or relocation of roads and houses, and establishing ‘retreat paths’ and open space areas along shore areas can reduce vulnerability to climate change. Plans for dealing with wastewater treatment with sewer systems and alternatives need to factor in effects of the changing climate. 

The environmental data and the science of climate change are sufficient to take action and the need is immediate. The state of Massachusetts is a leader in assessing impacts of climate change, but do the coastal communities understand the risk and vulnerability to climate change and its many impacts? Is starting to prepare and implement alternatives to deal with climate change a priority for Massachusetts citizens and its leaders?

Jeff Williams (Scientist Emeritus U.S. Geological Survey and Affiliate Faculty Un. Hawaii) living in North Falmouth has a 40 year research career writing and lecturing on coastal geology, sea level rise, storm effects on coasts, climate change, and need for climate adaptation. Most recently he was lead author on the U.S. National Climate Assessment report on Coasts and is currently writing a publication on Climate Change and Sea Level Rise Effects on Cape Cod.