Imagine your neighbourhood covered in ice, hundreds of feet thick. At the height of the last ice age, roughly 20,000 years ago, that is exactly how it might have looked. At that time about 97 per cent of Canada was covered in glaciers.
Glaciers form when temperatures remain cool enough that snow builds up rather than melts away. As the snow becomes heavier it presses down on the snow below compacting it into ice. As each new snowfall adds pressure on the snow below larger ice crystals are created. Some of these ice crystals have been known to grow as large as baseballs!
Because it is dense and free of bubbles glacial ice often appears blue.
Today 10 per cent of the land on Earth is covered with glacial ice that stores more than half of the world’s fresh water. If that ice all melted the sea would rise about 70 metres (230 feet).
Over the past two and a half million years the Earth has alternated between warm and cool periods resulting in regular ice ages. We are currently in a warm period (called an interglacial period) but the timing is right for the next ice age.
One factor that affects whether or not we experience an ice age is the amount of sunlight the earth enjoys.
The sun does not always radiate the same amount of daily sunlight towards Earth. One way we are able to see this variation in the sun’s activity is by counting sunspots, which indicate that solar storms are happening. Earth’s climate gets cooler with fewer solar storms.
Scientists have been noticing low numbers of sunspots in the past two years. Similar conditions happened in the 1600s, a time referred to as the “Little Ice Age” when the canals of Venice froze. Does today’s low solar activity make an ice age more likely?
The second factor that affects the possibility of an ice age is the amount of greenhouse gases in the atmosphere. Without this naturally occurring phenomenon the earth’s oceans would freeze. Greenhouse gases let sunlight pass through the atmosphere but prevent it from leaving, in effect trapping the heat of the sun. More greenhouse gas means more trapped heat which means a warmer climate.
Today because of the burning of fossil fuels, the primary greenhouse gas, carbon dioxide, is at its highest level ever recorded. This increase has meant temperatures around the world have risen and led to the melting of glaciers. As carbon dioxide can linger in the atmosphere for thousands of years it is highly unlikely we will see another ice age for 100,000 years!
How cold is an ice age? Surprisingly temperatures during the last ice age were only four to eight degrees Celsius cooler than they are today.
This cave in Alberta has been frozen since the last ice ageThis Canadian Cave Has Been Frozen Since the Last Ice Age
Article originally published in Brainspace Magazine