The Only Constant About Climate … is Change
One of the most straightforward modern definitions of climate is “the weather one can expect on a given day of the year” [Nature. 421.6926 (Feb. 27, 2003): p891].
It seems logical then that the definition of climate change is “change in the weather one can expect on a given day of the year”
Oh, how we wish it were that simple.
It took the International Panel on Climate Change (IPCC) 121 words to define climate change in their 2007 Synthesis Report. synthesis report.
The Only Constant in Climate is Change
In reality, the climate is always changing – climate has always been changing.
Climate stability is nothing more than a pause, a transient equilibrium, a moment of balance in an otherwise dynamic and constantly changing system.
Climate variability is the foundational theory of climate study, an intellectual endeavor that dates back over 400 years and much ealier if you include Mayans and Druids.
Where Did The Ice Go
There is not a single scientist in the world who will argue the fact that 22,000 years ago most of the northern hemisphere was covered with a giant ice sheet. In fact, so much water was stored in the northern hemisphere ice sheet that sea level around the world dropped by 200 to 300 feet compared to today’s levels.
The southern limit of ice extended along a line from Seattle to New York City. Montreal was under a mile of ice.
All of northern Europe was also under ice. The southern limit of the ice sheet in Europe extended from London through Berlin and Warsaw, nearly to Moscow. St. Petersburg, Russia was under a mile of ice. Southern Germany and the south of France was tundra.
The northern hemisphere ice sheet was stable at this position for thousands of years before it started to melt during what must have been major episodes of climate change.
Think Bungee Jumping
The ice sheets did not melt all at once.
When ice sheets melt, they retreat to the north but they do not just melt back all-at-once: They retreat and advance many times over thousands of years like a bungee-jumper bouncing by her/his feet off of a Las Vegas hotel tower. The “ice-bouncing” occurred for almost 12,000 years until the last remnants of the ice sheet melted and climate stabilized about 10,000 years ago. All this while, sea level was going up and down like water in a California reservoir.
Just because the ice sheets melted doesn’t mean climate stopped changing. Climate more or less stabilized near current conditions about 10,000 years ago, but since then there have been many warm and cold episodes.
The Little Ice Age
The most recent cold period was during the Little Ice Age from 1600 to 1850 when global temperatures were about 1 degree colder than today. The glaciers mapped at Glacier National Park in 1890 were formed during the Little Ice Age. Prior to 1650, during the Medieval Warm Period, Glacier National Park was glacier-free.
The bungee-jumping of climate oscillations never stops, but over the last 10,000 years, the long-term trend has been a warming Earth.
Why We Disagree
The cause for disagreement among scientists, the rancorous debate among and between environmental groups and the endless political grandstanding and civil activism that disrupts political discourse today is the extent to which humans have affected climate and the extent to which humans can do anything about changing the future climate.
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