As much as climate may be changing, we are only now heading back to te temperatures of the Roman era. Don't forget the 'Little Ice Age' that occurred after the 'Medieval Warm Period'. Farms and villages in the Swiss Alps were destroyed by encroaching glaciers during the mid-17th century. Canals and rivers in Great Britain and the Netherlands were frequently frozen deeply enough to support ice skating and winter festivals. The first River Thames frost fair was in 1607 and the last in 1814. There was even a little ice age in Central America and Africa.
http://www.spokesman.com/stories/2012/feb/23/world-headed-toward-mini-ice-age/
February 23, 2012
A report released at the end of January by British climate scientists at the University of East Anglia’s Climate Research Unit showed that the Earth’s average temperatures have dropped to the same levels seen back in 1997 before the so-called “big warmup.”
The average global temperature in 2011 was 0.68 degrees above normal. In the previous decade, the average temperature on this planet was 0.81 degrees above normal.
The British scientists agree with many Russian and Japanese climate scientists that the world could be headed toward a mini ice age sometime in the near future.
The new climate study suggests that the next significant cycle of cooling may rival the 70-year period in the mid-1600s that saw “frost fairs” held each winter season in London on the Thames River, which froze solid in January and February.