Temperature change is a normal occurrence on the changing earth that we live on. If we look back over the past 400,000 years, we see that the average temperature as determined by Antarctic ice-core records, show an 8-deg C change. The earth is normally about -4 to -5 deg C below the current temperature. This was during the four ice ages that occurred during this period.
The warm periods between the ice ages are relative short compared to the length of the ice ages which last about 100,000 years. Our current warm period has lasted longer than normal, about 6,000 years. About the same length of time that we have a recorded record of man on earth.
Carbon Dioxide levels have in the past followed along with the major changes in temperature. However in the past 200 years, this level has jumped and may have even prevented a return to another ice age.
The previous warm period was warmer that our current warm period and lasted almost as long as our current warm period followed by a 100,000 year ice age.
This may have been the time of the heavy forest growth and many fires, as the Carbon Dioxide levels also remained high. The Carbon Dioxide levels peaked at the same time that the warming levels peaked, but lasted much longer after the temperatures started to cool. This leads me to believe that the high Carbon Dioxide levels may have brought on the warm periods. As the Carbon Dioxide levels fell the temperature also fell.If we look at the last 1,100 years, we see only about a one deg C change with the current temperature about equal to what it was about 1,000 years ago. During the last few years the temperatures have leveled off and may be cooling back down again.
With so many factors affecting our global temperatures, I would expect more drastic changes in the future and if history repeats itself, we could be in for another ice age.
If in fact anything man is currently doing is affecting the temperature by keeping the earth warmer, it would be a positive thing.See: (http://www.epa.gov/climatechange/science/pastcc.html#ref) for more information.
In my life time I have seen large orange groves once common in north central Florida wiped out by colder weather and the land owners giving up and moved to more southern areas. I know that the reverse may have been true in other parts of the country and is only evidence that change is normal. There is an old saying, If you don't like the weather, just wait, it will change.
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