Global Climate Change

Medieval Global Temperature Optimum
The medieval global temperature optimum was a warm period that occurred in the North Atlantic area between 950-1250 AD.  During this period of time, scientists saw temperatures that were significantly warmer than the norm in areas such as Greenland, as well as parts of Europe and Asia. During this time, scientists also saw extended periods of drought in areas like the Sierra Nevada mountain range as well as parts of Australia.  Other areas, like northern China, experienced fluctuation between heavy rainfall and drought.  As studies were conducted, it was concluded that it was very likely that these climate changes were due to atmospheric circulation patterns.  These changes in patterns may have caused storm tracks to shift.  It is speculated that these shifts may have had an effect on why the temperatures during this time were significantly warmer.  However, despite these discoveries, many aren't so sure the medieval global temperature optimum is something worth studying, simply because the temperature change did not seem so significant.  According to these people, the shift in temperature was only around one or two degrees, making it not very much different than our climate today.  However, shortly after this time period, a period known today as the "Little Ice Age" occurred, drawing even more attention to climate change.
Little Ice Age
The Little Ice Age was said to have occurred somewhere between 1350 and 1850.  This however, like the medieval global temperature optimum, was not thought to be a global issue.  In fact, many scientists believe that the Little Ice Age only affected the Northern Hemisphere.  This slight decrease in temperature in these areas are said to have been caused by many different factors, ranging from heightened volcanic activity all the way to the decrease in human population.  Volcanic activity had an impact on the climate because of the ash it produced, which then blocked out the sun rays that were responsible for warming the planet.  When it came to decreases in human population, scientists believe that after events, like the Black Death, reforestation was able to occur, therefore allowing more carbon dioxide into the atmosphere.  Regardless of reason, the Little Ice Age was a time of colder winters, frozen waterways, and destroyed pieces of land due to glacial activity.  Overall, both the medieval global temperature optimum and the little ice age were some of the earliest moments where people began to see global or regional climate change.  These observations have now popped up again in todays society and have become major points of discussion both politically and socially.