Al Gore has made great use of a coincidence that the end of the Little Ice Ages, approximately 1850, and the natural increase in global temperatures coincided with the early stages of the Industrial Age and increased atmospheric CO2.
However, simply researching climate changes during the past 20,000 years shows that our current warming is modest, includes periods of cooling as CO2 increased, and correlates closely with solar fluctuations, not with CO2. Al's famous "hockey stick" has been totally discredited as it omitted the Little Ice Ages and the Medieval Warming Period. Even Al's guru James Hansen let him down, as NASA revised its temperature record for the past 100 years to reflect that six of the ten warmest years were over 50 years ago.
Al Gore has already made millions, and stands to make millions more, if Congress passes "cap and trade" legislation (learn about it here). The only approach to climate change that makes sense is adaptation, not expensive and vain efforts to reverse natural (and overwhelming) climate forces. Although the Earth is usually much warmer and polar ice free, at this moment in vast geological time we are in a rare ice age, and it looks like we will be plunging back into a period of true catastrophe, global cooling, before we in millions of years return to a "normal" Earth ten to twenty five degrees Fahrenheit warmer than present.
We should never confuse "coincidence" with "cause and effect."