The temperature fluctuations over thousands of years is a naturally occurring phenomenon. The earth has warmed and cooled and it is continuing to do so. What we are observing is the same trend as has occurred before the modern Industrial Age; mankind has almost no impact on global temperatures. If we want to talk about pollution in general then yes, that is definitely caused by man.
http://cdiac.ess-dive.lbl.gov/trends/co2/vostok.html