Excerpt: Beginning in the 14th Century, another major cool down ushered in what has been called the "Little Ice Age" lasting approximately 400 years. Glacier advances forced the Vikings to abandon their Greenland settlements. Poor crop yields caused food shortages throughout Europe and in early American settlements. In the late 18th and early 19th Century, warming began which has, with the exception of the major 1991 eruption of Mt. Pinatubo in the Philippines, continued throughout the 20th Century until 1998 when world temperatures, as measured by satellite and ground-based sensors, have leveled off and begun to drop.
Thus, significant historical evidence exists indicating there is always a change in climate underway and that, within the context of long-term world history, there appears to be nothing special about the last 60-80 years. So why does the IPCC report such a major discrepancy with other records of climate history? The answer lies in their reliance upon mathematical models -- and specifically one very convenient model. More: