earth has had many cycles throughout its history, ranging from vast ice-ages like the pleistocene, or small(in comparison), including the most recent, called the little ice age(a term coined by Francois E. Mathews) occuring from the 16th to the mid 19th century. while not considered a true ice age this series of events were not apparently caused by human intervention, the 16th century was not the coal burning, fossil fuel combusting modern era. instead it is widely understood that this tiny fluctuation in earth's envornment was caused by natural causes.
The intruiguing parts of this small ice age are the details of this almost forgotten event. During these "small" drops in temperature which caused devastating famines, ect. each temperature drop was preceded by an increase in temperature, global warming. and seeing as we, the human race has only inhabited the planet for, oh, .001% of its existence there really is very little knowledge about geological and enviornmental changes. It is really a marvel how much information scientist have deciphered from minute evidence left from these ecological events.
However, as a population, us humans should worry about our enviornment and even if global warming is not imminent, and we all are not on the brink of melting into oblivion, our stuborness and ignorance to accept and deal with enviornmetal issues must not lead us to destroy our planet.