Global warming has made nations across the globe adopt measures to fight carbon emissions and bring under control the rise in temperature of the earth’s surface. Would you be surprised to know something that is quite the contrary- that we are in the middle of an Ice age? You would be; but it is quite possibly true that the Earth, as we see it today, is in the middle of an Ice age for nearly the last 11,500 years.
Ice age or glacial period by definition is duration of time in which the earth’s surface is covered by ice sheets mostly. Between these glacial periods are interglacial periods during which the temperature of the earth’s surface remain at a level of what is today in our everyday life. Thus, our planet is in an interglacial period for nearly 11,500 years before which an Ice age existed and reached its peak about 21,000 years ago. Most of the entire North America today was covered under ice of 1 mile thickness during this period. Thus, an Ice age is a combination of glacial and interglacial periods and currently we are in the interglacial period of the Pliocene-Quaternary glaciation that began 2.58 million years ago.
“Solar experts are predicting a mini ice age in the next 15 years had there be a 60% drop in the sunspots”
During the interglacial period, the ice sheets remain in certain parts of the planet, which are currently in Antarctica, Greenland, and some in Alaska and Yukon Territory in the Northwest Canada. So you can pretty much surely say that, some thousands of years after, once again the earth will be frozen occupied by thick sheets of ice. The last ice age is one among the five major ice ages our planet has seen in its entire history.
Despite our planet being wayward in making the environment hospitable for human survival, it has offered the species the ability to adapt, transform, brave any unfavorable situation and thrive thereafter. Studies suggest that the human population was decimated to a few thousands during this harsh cold weather. Still, here we are- fighting climate change!
The other four major ice ages in history are:
- Huronian – 2.4 To 2.1 billion years ago
- Cryogenian – 850 to 630 million years ago
- Andean-Saharan – 460 to 420 million years ago, during late
- Karoo Ice age- 360 t0 260 million years ago
What causes ice age?
The orbit of our planet is oval in shape and is wobbling. It becomes a thin eclipse due to the gravitational pull of other celestial bodies out there in the vast universe. This makes the earth move away (and closer) from the sun. The earth reaches its farthest point from the sun once in 100,000 years making less sunshine fall on its surface and the mercury dipping extremely down.
In other words, it is called as the Milankovitch cycle, which is a combination of three different factors that decide the amount of solar radiation incident on the earth’s surface. They are eccentricity, obliquity, and precession.
“A hypothesis says that the entire earth was frozen 600 million years ago and is called the snowball earth”
Eccentricity is, as we have already seen the earth’s orbit becoming a thin eclipse, pushing the planet farthest away from the sun once in 100,000 years. Obliquity is the angle at which the earth is tilted and it varies between 22.1 and 24.5 degrees over a period of 41,000 years. Currently the planet is tilted 23.44 degrees and is moving towards 22.1 degrees.
Precession is when the earth wobbles in a circular fashion at its axis once in a period of 26,000 years. These three factors together affect the position of the planet relative to the sun giving rise to glacial and inter-glacial periods.
The little Ice age
The little ice age happened not much before as the major ice ages, but somewhere between the 13th century and 19th century or 1300 to 1850 AD , when the glaciers started raising in various geographical areas including Patagonia, New Zealand and Alaska, but at different time intervals. As they didn’t happen simultaneously, they are not regarded as a glacial period, but local climatic changes leading to more glaciations. NASA noted three time periods in which the temperature dipped down, starting from 1650, 1770 and 1850.
Anyhow, this doesn’t qualify for an Ice age because there is no strict definition. Some say that it is ice age, if it covers 400,000 square miles of land in non-polar regions. There will be ice!
Related video: What is an ice age?