20
The Medieval Warm Period
Perhaps a little history is in order, regarding what was happening one thousand
years ago, to put our effort in context. The period of time, from approximately
700 A.D. to 1200 A.D., is known as the Medieval Warm Period, or the Medieval
Climate Anomaly (or MCA for short; because more than just temperature changes
occurred). The term Medieval might conjure up images of castles and knights in
shining armor, which is accurate to a degree. During this period of time, temperatures around the North Atlantic basin were relatively warm; likely as warm as the
twentieth century, although we’re exceeding these temperatures now in the twentyfirst century. There are lots of data that support relatively warm temperatures during
the MCA including historical records of the time, the extent of various types of
vegetation in Europe, including crops, the extent of various types of organisms in
the oceans, and geochemical data from fossils and ice cores from glaciers. Warm
surface ocean waters decreased the extent of sea ice in the high North Atlantic and
allowed the Vikings to explore westward and colonize Iceland, Greenland, and
Newfoundland. Cultures flourished and expanded in Europe and Asia as agriculture
expanded due to the warm conditions. The increase in ocean water temperature also
may have increased the number and/or intensity of hurricanes at this time, based on
storm deposits seen along the North American east coast, and in the Bahamas and
islands in the Caribbean Sea. There is also some evidence that the rate of sea-level
rise increased slightly during the MCA.
All of these factors, rising sea levels, changing sea-ice conditions, hurricane
activity, precipitation patterns, water temperatures, are critically important to our
modern civilization. What’s more, in coastal areas, understanding how the beaches,
barriers and estuaries change in response to the rising sea level and storm activity is
vital to managing these areas and preparing for what the future will bring. Below the
surface of the barrier islands and the estuaries, within the layers of sand and mud,
we have the record of the past which informs us of what is possible in the future.
Good Morning Outer Banks
We’re coring in a particular spot where we know there was once a large inlet. How
do we know this? To explain, we need to rise early, 3 am, and venture out onto the
deserted roads of the Outer Banks. We do this with the help of dedicated law
enforcement officers who provide an escort. Why 3 am? We’ve been informed that
any earlier and you may have impaired drivers on the road. And, by 7 am, the roads
are becoming too busy. So, we have a short window of opportunity while most are
dreaming about the waves and beaches. The officers aren’t impressed that we need
to tow our GPR device (Fig. 2.4) at a mind-numbing 3–5 mph. We creep down the
dark highway, illuminated only by the flashing blue lights of the police car. The
radar antenna trails behind us, noisily dragging on the highway, sending signals into
D. J. Mallinson
The Medieval Warm Period
Perhaps a little history is in order, regarding what was happening one thousand
years ago, to put our effort in context. The period of time, from approximately
700 A.D. to 1200 A.D., is known as the Medieval Warm Period, or the Medieval
Climate Anomaly (or MCA for short; because more than just temperature changes
occurred). The term Medieval might conjure up images of castles and knights in
shining armor, which is accurate to a degree. During this period of time, temperatures around the North Atlantic basin were relatively warm; likely as warm as the
twentieth century, although we’re exceeding these temperatures now in the twentyfirst century. There are lots of data that support relatively warm temperatures during
the MCA including historical records of the time, the extent of various types of
vegetation in Europe, including crops, the extent of various types of organisms in
the oceans, and geochemical data from fossils and ice cores from glaciers. Warm
surface ocean waters decreased the extent of sea ice in the high North Atlantic and
allowed the Vikings to explore westward and colonize Iceland, Greenland, and
Newfoundland. Cultures flourished and expanded in Europe and Asia as agriculture
expanded due to the warm conditions. The increase in ocean water temperature also
may have increased the number and/or intensity of hurricanes at this time, based on
storm deposits seen along the North American east coast, and in the Bahamas and
islands in the Caribbean Sea. There is also some evidence that the rate of sea-level
rise increased slightly during the MCA.
All of these factors, rising sea levels, changing sea-ice conditions, hurricane
activity, precipitation patterns, water temperatures, are critically important to our
modern civilization. What’s more, in coastal areas, understanding how the beaches,
barriers and estuaries change in response to the rising sea level and storm activity is
vital to managing these areas and preparing for what the future will bring. Below the
surface of the barrier islands and the estuaries, within the layers of sand and mud,
we have the record of the past which informs us of what is possible in the future.
Good Morning Outer Banks
We’re coring in a particular spot where we know there was once a large inlet. How
do we know this? To explain, we need to rise early, 3 am, and venture out onto the
deserted roads of the Outer Banks. We do this with the help of dedicated law
enforcement officers who provide an escort. Why 3 am? We’ve been informed that
any earlier and you may have impaired drivers on the road. And, by 7 am, the roads
are becoming too busy. So, we have a short window of opportunity while most are
dreaming about the waves and beaches. The officers aren’t impressed that we need
to tow our GPR device (Fig. 2.4) at a mind-numbing 3–5 mph. We creep down the
dark highway, illuminated only by the flashing blue lights of the police car. The
radar antenna trails behind us, noisily dragging on the highway, sending signals into
D. J. Mallinson