Offnominal

If you were to visit the Earth in the mid-Cretaceous, you'd find the north pole a very different place. Despite the prolonged periods of darkness that the polar regions endured then as they do today, the northern edges of the continents were forested by broad leaf trees that today live only much further south.  Among those trees moved dinosaurs. Some of them appear to have migrated from more equitable climes, enjoying the growth of foliage that comes in light-drenched Arctic summers. Others probably lived out their lives in the north. Offshore, in the waters of the Arctic Ocean, swam long-necked pleisiosaurs and enormous mosasaurs. It was a much warmer pole — perhaps as much as 8ºC warmer on average than those areas are today. Even so, the region still saw periods of freezing weather, and both the dinosaurs and trees that lived there must have had dramatic adaptions to living through the periods of long, frosty night.

The sea-going creatures of the time would have been better able to exploit the northern oceans without making big changes in their habits.  The Arctic Ocean was a warm sea, with some readings indicating water at 30ºC — warm enough for a pleasant bath and about what you'd find today in the Caribbean. No ice bergs, much less sheets of ice, dotted this ocean. It was that much warmer.

By the late Cretaceous, well before the events that saw dinosaurs off the stage, the climate had already changed. It wasn’t as cold as it was today, but it was a good deal colder. Bath time at the North Pole had ended.

Over the course of the last sixty-five million years, temperatures at the North Pole have fluctuated. It’s not reached that balmy mid-Cretaceous toastiness, but it’s certainly been warmer than today. About 2.7 million years, when world temperatures took a sudden shift for the colder, ice started to pile up in the Arctic. Part of the reason for this wasn’t just a change to colder weather, but a change to more seasonal weather. The positions of the continents helped shape the flow of deep water currents, providing additional humidity — and ice — to the Arctic. The great Atlantic “conveyor” was at work, sending submarine rivers of water flowing north and south, both being shaped by and shaping the resulting climate.

The researchers are the first to find evidence showing that this was caused by the stratification of ocean water, due to an increase in freshwater. This means that water mixed less than previously, forming layers of different densities in different strata and at different depths. When spring came, the layers closest to the surface began to heat up. Since the water did not mix, the temperature of those layers continued to rise, and increasing amounts of water evaporated. During the summer months, this effect intensified, as higher temperatures increase stratification; in winter, however, the water began mixing again, and temperatures dropped more than in previous years.

Climate changes. And yes, it certainly did this long before we built the first coal-fired power plant — even long before the coal itself was laid down. Even in the last 2.7 million years, there have been warmer periods at the poles, so that the oldest ice we know of is less than a million years old.

So does that absolve us of responsibility for the current period of global warming?  Hardly.  Trees fall in the forest without our intervention.  But when a tree falls after someone has applied a number of hard blows from a sharp ax, it's a good bet there's some relationship.  Global climate changes without our intervention.  But when it warms at the same time that we are sending CO2 levels to values not seen in at least the last 650,000 years, there's just as good a reason to be suspicious that we're the causative agent in this round of climate change, as there is to suspect that guy toting the ax is behind the felling of that unfortunate tree.

However, Republicans in Congress spent last week still sneering disdainfully at the whole idea of climate change as security agencies pointed out the threat to our nation.  Meanwhile, out in the real world, climate change carries on even without GOP permission. And, as it seems to do every time we make a measurement these days, change seems to be coming faster than expected.  Last year the Northwest Passage was ice free by September, setting off a more-than-minor earthquake in diplomatic relations as nations began jockeying for not just transportation access, but resources that lie under the Arctic Ocean.

This year seems to be headed for an event much more spectacular… and frightening.  An ice-free North Pole.

It seems unthinkable, but for the first time in human history, ice is on course to disappear entirely from the North Pole this year.

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Seasoned polar scientists believe the chances of a totally ice-free North Pole this summer are greater than 50:50 because the normally thick ice formed over many years at the Pole has been blown away and replaced by huge swathes of thinner ice formed over a single year.

There are others who are more skeptical of seeing the North Pole without ice this season, and honestly, there are so many factors involved that it's very difficult to predict.  But the fact that "old" ice has been greatly reduced in the Arctic, to be replaced by thin seasonal ice, makes this event possible for the first time in… well, we don't know how long.

Will an event that may not have occurred this side of the Pleistocene be enough to wake up the doubters? Probably not. After all, don’t forget that it was chilly in some parts of the US this spring and that proves global warming is a hoax perpetuated on the gullible public by "Algore."  Besides, many of the same people who don't believe in climate change, also don't believe there was a Pleistocene (since the world is only 6,000 years old).

In the meantime…

Inuit natives living near Baffin Bay between Canada and Greenland are also reporting that the sea ice there is starting to break up much earlier than normal and that they have seen wide cracks appearing in the ice where it normally remains stable. Satellite measurements collected over nearly 30 years show a significant decline in the extent of the Arctic sea ice, which has become more rapid in recent years.