“Did dinosaurs exist and did the Ice Age period exist?” My son asked me in 2009 after watching the movie Ice Age. In my past I had been quite religious, loving the abstract. On the other hand, my son follows logic. Our discussions lead to lengthy debates. These and many other of his questions have led me to inquire, investigate and seek knowledge.
In my search for answers, I started with the question whether Ice Age existed. I found out that the history of Ice Age is a story of survival of life. This triggered my mind to the current discussion on global warming and what we can do to have sustainable life on our planet.
I discovered that there have been several Ice Ages in the past. In fact, we are currently living in an interglacial period. This is a period when warmer global average temperature lasting thousands of years separates glacial periods within an ice age. We are living in an interglacial period of Quaternary ice age, which began 2.58 million years ago. The Quaternary ice age is also known as Holocene.
The Quaternary Period is divided into two eras, Pleistocene and Holocene. Pleistocene is popularly known as Ice Age when the climate cooled and ice sheets began covering Earth’s landmasses. Holocene climate begins when the Earth started to warm again, and glaciers melted into the oceans.
Six or seven major Ice Ages have been identified
I also discovered that great amounts of studies are available to help us understand how we can respond to climate issues.
Let’s start with paleoclimatology, the study of earth’s climate during the entire history of the Earth. Paleoclimate research uses geologic and biologic evidence preserved in sediments, rocks, tree rings, corals, ice sheets and other climate archives to reconstruct past climate in land and water environments around the world.
Paleoclimate reconstructions provide evidence for the baseline level of climate and environmental variability before humans began using instruments to measure different aspects of climate and weather.
Paleoclimate data has been analysed and variations in the volume of ice in the ice caps can be reconstructed over a greater part of the last million years. In this record six or seven major Ice Ages have been identified with warmer periods in between the periods.
Cold periods are known as Ice Ages; warm periods are known as interglacials
The Earth has a history of going in and out of cold periods known as Ice Ages, and warm periods known as interglacials.
Scientific records of carbon dioxide levels in the atmosphere go back to 800,000 years. But people can only give educated guesses about the climate earlier than that, according to Global Warming for Dummies.
Going back before recorded history, scientists rely on indirect methods to understand climate trends. The indirect methods include studying ice cores, tree rings, records of lake levels, records of glacier advance and retreat of pollen distribution in the past.
A particularly valuable information source is the record stored in the ice that caps Greenland and the Antarctica continent.
How Ice Age forms
Ice caps are several thousand of metres thick. Snow deposited on the surface gradually becomes compacted as further snow falls becoming solid ice. The ice moves steadily downwards eventually flowing outward at the bottom of the ice sheet. Ice near the bottom will have fallen on the surface many tens of thousands of years ago.
Causes of global warming
Analysis of ice at different levels is used to provide information about conditions prevailing at different times in the past. This analysis investigated greenhouse gases, temperatures prevailing at the time, cloud cover, long-term climate trends and solar cycles.
Is Ice Age evidence for historical global warming?
At Russia’s Vostok station in East Antarctica drilling was carried out for over 20 years.
Analysis of small air bubbles trapped within the ice shows what was present in the atmosphere for the time at which ice was formed. Gases such as carbon dioxide or methane, dust particles that may have come from volcanoes or from sea surface are also contained within the ice.
Such a construction from Vostok Ice cores for temperature and content of carbon dioxide and content of methane shows the last Ice Age began about 20,000 years ago. It also demonstrates that close connections which exist between temperatures and carbon dioxide and methane concentration.
Data from ice cores can also take us back 200,000 years or so. Going further back over the past million years the composition of oceans sediments can be investigated to yield information. Fossils of plankton and other small sea creatures deposited in these sediments also contain different isotopes of oxygen.
Ice Age is environmental adaptation to the changes in climate
The sun goes through a cycle that brings us closer to or further away from the earth. The cycle ultimately affects the temperature of this planet, and thus climate. The sun itself has not changed significantly over the last million of years or so. However, the variations in the earth’s orbit, the distribution of solar radiation has varied in regular way during the last millennium.
Although the total quantity of solar radiation reaching the earth varies very little, the distribution of that radiation with latitude and season over the earth surface changes considerably.
In 1867 a British scientist James Croll explained that the major Ice Ages of the past might be linked with these regular variations in the seasonal distribution of solar radiation reaching the Earth.
Milankovitch theory named after Milutin Milankovitch, a climatologist from Yugoslavia, developed Croll’s ideas further in 1920. Inspection by the eye of the relationship between the variations of polar summer sunshine and global ice volume suggest a significant connection.
I concluded that this study provides us with an historical perspective of how climate has changed in the past. Ice Age is environmental adaptation to the changes in climate. In fact, environmental factors, such as continental drift, solar energy, greenhouses gases in the atmosphere, and the variation in earth’s orbit have all affected the climate of earth over time.
As scientists become increasingly aware of how climates have been influenced in the past, they can develop models that help predict how increased carbon dioxide levels and other changes might impact the climate of earth in the future.