Figure 1 shows the extent of Antarctic sea ice for 2010 up to September 10. Ice extent has been about 1 million square kilometers above the 1979 – 2000 average. Notice the 2009 ice amount was above average as well. This matches reports of record cold temperatures around the Southern Hemisphere. On July 27, 2010 we learned from Peru, “Temperatures plummeted to below -20°C prompting the government to declare a state of emergency for nearly half of the country Friday.”- Source
From Argentina, “Local newspapers reported that the temperature plunged to -1.5°C in Buenos Aires, on Friday—making it the coolest day in a decade for the capital. Even the beaches saw white powder. The coastal resort city Mar del Plata was blanketed by snow for two days straight.
One report with the headline “South American winter starts with a severe cold snap” reports, “Argentina, Paraguay, Uruguay and Brazil are also experiencing the cold snap, which has killed millions of fish and an untold number of livestock.”
While the mainstream media ignore cold and recent changes in sea ice, it’s a good time to give an overview of different ice conditions. Melting ice has two attractions for global alarmists. It is supposedly a sign of warmer temperatures and it plays to people’s unjustified fears about rising sea levels. This is why it was a central part of Gore’s movie, “An Inconvenient Truth.”
Different Ice Categories
Ice is formed from water freezing or snow melding (a thing formed by merging or blending) under heat and pressure into ice. Both can exist as brittle or plastic. Under sufficient heat and pressure, ice will become plastic and flow, which is an important feature to understand about the dynamics of glacial movement.
Sea ice forms when seawater temperature drops below –4°C. It is lower than for freshwater because of the salt content, but the ice when formed is salt free because of the formation process. This was a major question Wales and Dymond, two scientists sent by the Royal Society to Churchill Manitoba in 1769 to observe the Transit of Venus, were asked to determine. They couldn’t resolve the issue because saltwater spray contaminates most sea ice.
The major areas of sea ice are the seasonal expansion and melt in the Arctic Ocean and around Antarctica. We’ve been measuring these with satellites since 1978, but it took two years to determine an accurate interpretation, so 1980 is a safe base. Even then there are differences between interpretations and these are examined and compared admirably at Anthony Watts web site.
A great deal was made of decreasing summer extents of ice, especially in the Arctic, but it followed the warming trend and variations from year to year were well within natural variability. The influence of wind and ocean currents are important, but were ignored in the exploitive alarmism. Now the ice is back to, or even above average for the period of record, it is ignored.
Ice on the land is formed when snow accumulates to a sufficient depth for the pressure of weight to compress the snow so it transforms by melding into a solid mass. At this stage it is solid but brittle. If sufficient weight or pressure occurs normally when thickness is 50m then the ice becomes plastic and will flow. In a glacier the upper layer is brittle and sitting on a plastic layer. When the plastic layer moves the brittle layer is dragged along, but cracks into crevasses when the plastic layer flows over an uneven surface.
A glacier forms when winter snow survives a summer melt. This can occur at altitude or latitude, but contrary to the common assumption this can occur with cooler temperatures or increased snowfall. Similarly, the glacier can decrease in size because of increased temperatures or decreased snowfall. Snow that accumulates at altitude forms what are called alpine glaciers. Snow that accumulates at high latitudes generally forms what are called continental glaciers. It is vague distinction, especially since the processes involved and the land forms that result are similar.
There are two continental glaciers today, Greenland and Antarctica and both sit on land that is dramatically depressed by their weight, so that much of each glacier is below sea level. The average temperature of these glaciers is such that a dramatic warming must occur for significant melting: Antarctic is at least –20°C. Most of the change in these glaciers is caused by varying snowfalls and changes in the rate of outflow of the ice to the oceans. Alarmists incorrectly attribute all movement of the front of the glaciers (the snout) to changes in temperature. This can be a factor but changes in the rate of accumulation of snow at the top of the glacier above the permanent snow line are just as important. Currently we scientifically monitor approximately 10 percent of the alpine glaciers and half are advancing and half retreating.
When the continental glaciers advance into the oceans it creates a different form of ice called Shelf Ice. This has a flat surface and is thickest at the land’s edge (900m) and thinnest (300m) offshore. When the continental glacier increases in volume the ice advances and pushes the Shelf Ice out where it is affected by wind, waves and tides. Large pieces called tabular icebergs break off as they have for millennia, but now each is reported incorrectly as proof of global warming.
Figure 2: Map of location of the Titanic sinking (A).
Source: Google maps
In other places when the glacier enters the ocean large blocks break off to become the familiar icebergs, like the Titanic struck. The last part of he 19th century and first decade of the 20th century were very cool. Figure 2 shows where the Titanic sank and at 41°N is surprisingly far south. They claim, incorrectly, that an increase in glaciers is a sign of global warming. It isn’t. It’s a sign of glacier growth which results in greater ice flow to the oceans. As a result more icebergs are created.
Next time you see a story about ice determine if they’re talking about Sea ice, Shelf ice, continental glacier ice, or Alpine glacier ice. Then remember that snowfall is as important as temperature in the formation and dynamics of glacier movement.