The discussion of climate change will stick with humans until we somehow decrease levels to a point that will keep us healthy, and help prevent plants and animals from dying that would not typically die if it were not for this spike carbon levels. We have compared current levels with past levels and there has obviously been a tremendous spike in the last 150 years. There are also little spikes and drops of carbon and oxygen levels that are out of the ordinary way before humans came into existence. What accounts for these changes is the question at hand.
Wide spread changes occurred to the carbon cycle over 100 million years ago and what scientists have discovered is that it was due to large amounts of volcanic activity. Massive amounts of volcanic activity can have huge impacts on the surrounding area. If we recall just last summer the problems that the volcano in Iceland caused us. Flights were canceled and the area was covered is an ash cloud. These are just two small examples of what problems came about for humans. Now it is time to see a bigger picture of what happened 100 million years ago. Volcanic activity introduced more then the usual amount of carbon dioxide and sulfur into the atmosphere. When this occurs, it created an increase in the nutrient phosphorous. An algae in the ocean that feeds off this nutrient is called phytoplankton. The death of phytoplankton create phytoplankton blooms. Their decomposing bodies lead to a depletion of oxygen levels in the ocean. In this case, the amount of phytoplankton that thrived was beyond anything had happened before and the effects were devastating. The amount of volcanic activity that occurred dropped oxygen levels so low that one-third of marine life perished.
Scientists were able to deduce this information by studying plant cuticles from that time era. From the cuticles, scientists were able to figure out what the carbon dioxide levels were during that period. What was discovered was shocking. Carbon dioxide levels increased by nearly 20 percent! Granted, these events took place over hundreds and thousands of years. Humans were able to make this impact in less then 150 years. Still, it is interesting to see a naturally occurring issue, competely out of our control, that can cause such devastation. The problem is that some people still think that global climate change at this point in time is due to naturally occurring events. While this may be true to some degree, it is certainly not an educated answer. Eventually this debate will become irrefutable.