Our “recent” (geologically speaking) temperature history:
By Lawrence Solomon in the Financial Post
Thank your lucky stars to be alive on Earth at this time. Our planet is usually in a deep freeze. The last million years have cycled through Ice Ages that last about 100,000 years each, with warmer slivers of about 10,000 years in between.
We are in-betweeners, and just barely — we live in (gasp!) year 10,000 or so after the end of the last ice age. But for our good fortune, we might have been born in the next Ice Age.
Our luck is even better than that. Those 10,000-year warm spells aren’t all cosy-warm. They include brutal Little Ice Ages such as the 500-year-long Little Ice Age that started about 600 years ago. Fortunately, we weren’t around during its fiercest periods when Finland lost one-third of its population, Iceland half, and most of Canada became uninhabitable — even the Inuit fled. While the cold spells within the 10,000 year warm spells aren’t as brutal as a Little Ice Age, they can nevertheless make us huddle in gloom, such as the period in history from about 400 AD to 900 AD, which we know as the Dark Ages. We’ve lucked out twice, escaping the cold spells within the warm spells, making us inbetweeners within the inbetween periods. How good is that?
We aren’t alone in having been blessed by good weather. About 2000 years ago, around the time of Caesar and Christ, temperatures were also gloriously warm, some say much warmer than those we’ve experienced in recent decades. That period — the centuries immediately before and after Caesar and Christ — are known as the Roman Warm Period, a time of wealth and accomplishment when the warmer weather filled granaries and extended grape and olive growing regions to lands that had previously been unarable.
Another period of unusual warmth came about 1000 years after the Roman Warm Period, during the centuries before and after the year 1000, in what is known as the Medieval Warm Period. In this period, again warmer than the present time, the world shucked off the insularity of the Dark Ages to allow civilization to once again blossom. England, then positively balmy, became a grape-growing region. In the North Atlantic, the Arctic sea ice released its grip over Greenland, making this vast island hospitable for Viking settlers. In the Canadian Rockies, majestic forests — trees larger than those of today — thrived before their decimation by the glaciers that came in with the Little Ice Age.
Another 1000 years and we come to our time, known to climatologists as the Modern Warm Period. What a great time of technological and cultural advancement we’ve known, one of unprecedented prosperity, human longevity, and human comfort. For a brief period in the 1970s it appeared to some scientists that the climate that had abetted our prosperity had turned — this was the fear of global cooling that then made headlines. Though many now mock those fears of climate cooling, the scientists were eminent and the science was sound — after all, given Earth’s history through the eons, and the passage of 10,000 years since the last ice age, it was hardly outlandish to believe that time of warmth was up.
It wasn’t then — the decades after the 1970s have been about as good as it gets. But it could be now. In fact, some of the same scientists who in the 1970s warned of a new cold spell still believe it could be imminent. Other eminent scientists with compelling new evidence have recently joined them in predicting the end of our Modern Warm Period. They and others note that the warming of the planet stopped 11 years ago and that the planet has begun to cool.
If a new Dark Age does come, it could be rapid, marked by plunging temperatures and extreme weather events. Such was the transition from the Roman Warm Period to the Dark Ages and from the Medieval Warm Period to the Little Ice Age. To date, we have seen no plunging temperatures, no uncharacteristically extreme weather.
If we are living on borrowed time, as the history of the world would suggest, this reprieve would be but one more blessing to count. We should enjoy the warmth while we can, and hope that it persists so that the world our children and grandchildren inherit will be no less warm and welcoming.
Read more: http://network.nationalpost.com/np/blogs/fpcomment/archive/2009/10/30/lawrence-solomon-enjoy-the-warmth-while-it-lasts.aspx#ixzz0VcUM2rMH