1. Evidence of Little Ice Age

Modern Scientific data

• Temperature records
• Ice cores
• Ice delivered debris on ocean floor

• Tree rings
• Wide rings show warm summers
• Narrow rings cold summers

• Glacial action
• Movement of glaciers in Alps and Scandinavia
• Mer de Glace at Chamonix at foot of Mont Blanc
• Exorcism of glacier

• Reports of harsh winters
• Europe and North American colonies
• Thames River and New York Harbor frozen during winters
• Orange groves in China killed

• Eskimos kayaking as far south as Scotland
• Sea Ice in North Atlantic
• Snow on Ethiopian's mountains
• Investigations of newspapers and journals
• Investigation of clouds in paintings of time

 
1. Solar Activity:
 - The sun experienced an extended quiet period in which its intensity fell by as much as  1/4 of a percent. This leads to less radiant heat emitted from the sun to neighboring bodies, therefore a cooling occurs.
 - Decrease in observable sunspots were noted. Amount of sunspots is correlated to the activeness of the sun-more sunspots means more emission of radiant heat from the sun. During this declined period of sunspots, people have connected it to Maunder Minimum, who proposed this idea of sunspot and solar activity correlation.
 

2. Volcanic Activity:
 - During the Little Ice Age, records show that this was a period of numerous volcanic eruptions.
 - As volcanoes erupt they spit particles and gases into the air, an event leading to the aerosol effect.
 - Aerosol effect reduces the amount of incoming solar heat by relecting it back into space. This increases the earth's albedo. A higher albedo coincides with lower temperatures-a cooling if you will.
 - An example of this idea can be seen in the eruption of Tambora. This eruption produced so much gases and particles that it lowered earth's temperature enough that it robbed Europe of a summer the following year (The year without a summer).
 

3. Surface Albedo:
 -Continued low temperatures, for whatever reason, produced snow and ice.
 - More snow and ice equals more reflective surfaces to deny sun's radiant energy from reaching teh earth's surface leading to additional cooling. Again staging a situation for the formation of more snow and ice.
 - A positive feedback mechanism.
 

4. Milankovitch Theory:
 - Eccentricity. The degree of roundness of the earth's spherical shape.
 - Tilt. Stronger tilt leads to a more varied seasonal climate.
 - Precession of Equinox. Position of the earth on its elliptical path around the sun.
 - During the Little Ice Age (LIA), all these factors were thought to have been situated in a fashion that allowed for such a prolonged period of cooling.
 - This theory is met with scepticism in that some of the cycles mentioned (eccentricity, tilt and precession of equinox) require more time than what was allowed by the LIA period.
 

5. Ocean-Atmosphere Conveyor System:
 -Occurs only in the N. Atlantic ocean-atmosphere domain.
 - Warm tropical Gulf Stream ocean currnts and winds are conveyed up to the north to meet cold Arctic waters and air.
 - Within this area you have atmospheric lows and highs:
atm. lo: Forces air away from air mass center due to correolis effect. Outward tending winds will force ocean currents to diverge from the center as well.
atm. hi: Opposite of atmospheric lo.
 - It is these divergent tendencies of the N. Atlantic that keeps the Gulf Stream powered. If an atm. hi replaced an atm. lo currents would converge, thus weakening the Gulf Stream which was thought to possibly have occured during the LIA.
 - Lack of warm winds and currents reaching the north would not warm the cold climate of the north possibly producing snow and ice.
 - This idea holds very sceptical because this event was localized, whereas the LIA was a global scale event.