Ice Age is one of the most famous animated film series that deals with the life and struggles of animals that had been part of the earth’s biodiversity during the ice age. What is an ice age and when is the next ice age due? Ice age, which is also known as glacial age, is the refrigeration of the earth’s climate. Ice sheets and other types of glaciers expand to cover large areas of land, beyond the Polar Regions, reaching up to the temperate zones of today. The chronology of the earth’s geological history shows that there have been at least five major ice age periods, interspersed with warm interglacial periods. The last major ice age began in the Pleistocene epoch about 2.6 million years ago and the current interglacial warm period began when it ended; almost 12,000 years ago. There is evidence of at least 17 cycles between glacial and interglacial periods with the glacial periods lasting longer than the interglacial periods.
The five significant ice ages are named the Huronian (2.4-2.1 billion years ago), Cryogenian (850-635 million years ago), Andean-Saharan (460-430 mya), Karoo (360-260 mya) and Quaternary (2.6 mya-present). The two main sources of evidence for the determination of glacial and interglacial periods come from:-
- Glacial Ice Cores retrieved from Antarctica: The Vostok Ice Core retrieved from Antarctica provides a climate record of the past 740,000 years. Analysis of the ice core showed that the interglacial periods 430,000 years ago was very long -28,000 years.The present interglacial period is nearly 12,000 years long and is also similar to the 28,000-years-long interglacial period in terms of amount of greenhouse gases in the atmosphere and change of climate.
- Oceanic Sediment Cores: Also known as Marine Cores, these are retrieved from the ocean bed through drilling. They provide data about the past in terms of climate, biodiversity, atmospheric gases, etc.
The latest mini-ice age that was experienced by human beings was not too long ago. The global temperature of the medieval warm period, which allowed the Vikings to travel the ice–free Arctic seas and colonize Greenland, was comparable if not more than the current global temperature. This period of global warming was followed by the Little Ice Age which began in the end of 1200s and lasted until the 1800s, probably brought to an end by the effects of the industrial revolution. So, when is the next ice age due?
According to Milankovitch theory, the advent of the ice age depends on the coincidence of the following three conditions:
- Elongation or eccentricity: Eccentricity is the shape of the Earth’s orbit around the Sun. It is constantly fluctuating with the orbital shape ranging between more and less elliptical, every 100,000 years. This alters the distance from the Earth to the Sun which in turn reduces or increases the amount of radiation received at the Earth’s surface in different seasons. The northern hemisphere experiences winter while the southern hemisphere experiences summer at perihelion position, which is the position where the distance between the earth and the sun is the least. The opposite happens at the aphelion position which is the position where the distance between the earth and the sun is the most. The solar energy received at the perihelion is 20-30% more than the energy received at the aphelion position. These fluctuations around the globe result in prominent changes in the Earth’s climate and glacial regimes. This means that the winter experienced at the aphelion would be bitter and due to the slow rotation of the earth at the aphelion (as per calculations based on Kepler’s second law), the winter would get more time to strengthen itself. For example, the glaciers from the north may start to extend southwards.
- Rotation of Precession: While the bottom part of a top is spinning, the top part also sort of revolves. The earth spins like a spinning top on its axis, while its axis also sort of revolves. It takes 26,000 years to complete one such revolution. Because of this movement, we notice the change in the night sky during different seasons. If you compare the night sky of summer in the northern hemisphere today to the night sky of summer in the northern hemisphere 5,000 years ago, it will be very different. When the precession of equinoxes sends the glaciations-prone northern hemisphere to the aphelion position, the winter becomes fierce, freezing the arctic and most of the northern hemisphere.
- Tilt or Obliquity: Currently, the tilt of the earth’s axis or its obliquity is at 23.5 degrees. But every 41,000 years, the obliquity shifts between low (22.1 degrees) to high (24.5 degrees). When the obliquity is at its lowest, the higher latitudes don’t receive much sunlight, leading to increase in ice cover over these latitudes.
According to the Milankovitch criteria, to predict the next ice age, we can use the above information and find out when the next ice age is due. The earth’s orbit is almost circular today and 10,000 years from now, the orbit will be an ellipse. Obliquity will be at its lowest in 12,000 years from today while the precession would have reversed in almost10,000 years. So, we can predict that almost 10 to 12 thousand years from now, a new ice age may begin.
John L. Casey, former white house space policy advisor, former space shuttle engineer and NASA advisor, has written a book called Dark Winter. Casey, who is now a climatologist, and president of the Space and Science Research Corporation, wrote in his book that we may already be in the midst of a mini-ice age. The cold wave that hit North America in the winter of 2017-18 may be the proof that supports his theory. David Dilley, former meteorologist for the U.S. Air Force and senior forecaster with National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service wrote in his article ‘Suppressing the Truth – The next global cooling cycle’ about how the Earth undergoes a cooling cycle every 230 years which might lead to a mini ice age. He also added that due to the severity of the impact of human beings on the climate of the earth which has lead to global warming, organisations like NASA and IPCC (Intercontinental Panel on Climate Control) do not want to acknowledge global cooling as it would undermine everything that countries and other organisations have tried to do to curb global warming.
Other researchers and scientists have found out the additional reasons behind global cooling that complement the Milankovitch theory. According to a new model that can forecast solar cycles most accurately so far has predicted that solar magnetic activity will drop by 60% from 2030. This might lead to a mini ice age, as it may lead to conditions similar to that which lead to the Little Ice Age. Sun’s magnetic activity waxes and wanes in a cycle of 10-12 years and during the minima, solar radiation declines, sunspots vanish, and solar flares become very rare. Dr Valentina Zharkova, who is an astrophysicist and mathematician, said that the waning phase of the sun’s magnetic cycle beginning in 2030 will create the properties of ‘Maunder Minimum’ which is when temperatures across the Northern Hemisphere had declined leading to a time of crisis during the Little Ice Age. River Thames flowing through London froze many times during the Maunder Minimum. Droughts struck and the crop-growing period shortened, leading to widespread famines. Even natural disasters like volcanoes erupted, supported by the sea ice. The smoke and ash filled the atmosphere leading to further decrease in sunlight reaching the earth’s surface. Due to the increase in ice cover, earth’s albedo increased which means that whatever amount of sunlight reached the earth was mostly reflected back by the ice, snow and glaciers.
Anthropogenic activities that have contributed to the massive increase in Carbon Dioxide and other greenhouse gases in the earth’s atmosphere may not let the natural cycle of earth’s cooling take place. Global warming has become a dinner table conversation since the early 2000s because of the wide circulation of theories and facts about the rising temperature of earth. Based on many scientific reports about the same, former U.S. Vice-president Al Gore had predicted that the arctic ice caps would have melted by 2014. That has not happened as of yet. According to a study by NASA in 2015, an increase in Antarctic snow accumulation that had begun 10,000 years ago had added enough ice to the continent to outweigh the increased losses from its thinning glaciers. The research even challenged the IPCC’s 2013 report which said that Antarctica was losing overall land ice. Instead, new analysis of satellite data showed that the Antarctic ice sheet had a net gain of 112 billion tons of ice a year from 1992 to 2001 and 82 billion tons of ice per year between 2003 and 2008.
So, are we really heading towards global warming or global cooling? We are all decked up to curb global warming. But are we ready to face an ice age? To prepare ourselves for global cooling, we should be able to answer the question: when is the next ice age due?