http://www.forbes.com/sites/larrybel...-temperatures/
'Has there been ?recent? warming? Yes, the global climate has definitely warmed since the Little Ice Age (about 1400-1700 AD), and it will likely continue to warm for another 200-300 years, in fits and starts, towards a max temp roughly matching that of the Medieval Warm Period. That time followed a colder period before the founding of Rome between about 750 BC to 200 BC. By 150 BC the climate had warmed enough for the first grapes and olives to be cultivated in northern Italy. As recently as 1,000 years ago, Icelandic Vikings were raising cattle, sheep and goats in grasslands on Greenland?s southwestern coast.'
'Then, around 1200, temperatures began to drop, and Norse settlements were abandoned by about 1350. Atlantic pack ice began to grow around 1250, and shortened growing seasons and unreliable weather patterns, including torrential rains in Northern Europe, led to the ?Great Famine? of 1315-1317.
'Temperatures dropped dramatically again in the middle of the 16th century, and although there were notable year year-to-year fluctuations, the coldest regime since the last Ice Age (that so-called ?Little Ice Age?) dominated the next hundred and fifty years or more. Food shortages killed millions in Europe between 1690 and 1700, followed by more famines in 1725 and 1816. The end of this time witnessed brutal winter temperatures suffered by Washington?s troops at Valley Forge in 1777, and Napoleon?s bitterly cold retreat from Russia in 1812'
'Although temperatures have been generally mild over the past 500 years, we should remember that significant fluctuations are normal. The past century alone witnessed two distinct periods of warming. The first occurred between 1900 and 1945, and the second, following a slight cool-down began quite abruptly in 1975. That second period rose at very modest rate, if at all, until 1998, and then stopped and began falling again after reaching a high of 1.16ºF above the average global mean temperature. There hasn?t been any warming for at least a decade and a half, and possibly, considerably longer.
It?s also worth remembering that about half of all estimated warming since 1900 occurred prior to the mid-1940s despite continuously rising CO2 levels. Also consider that, even today, about 97% of all current atmospheric CO2 derives from natural sources.'