Ice Age Water and Modern-Day Applications
The Earth’s water resides in liquid form in the oceans, lakes and rivers, in moisture form in the air and soil, and in solid form as ice and snow. Despite the seemingly stable total amount of water on the planet, water can redistribute and move from place to place—a key factor in ice ages and their long-term consequences for Earth’s climate.
During an ice age large portions of the massive glacier ice sheets that cover the land can melt and retreat, raising global sea levels. Scientists have known for a while that at the end of the last ice age (the Little Ice Age) the ice was retreating at a rate unprecedented in the geologic record, raising sea levels faster than ever before.
But why did that happen, and what can we learn from it? To answer those questions, scientists are digging deep into the Earth’s history. And they’ve found some fascinating answers in the process.
Scientists have analyzed sediment from the bottom of Arctic and Greenland ocean waters. They’ve sifted through the tiny remains of algae and single-celled organisms, as well as the mineral debris that accumulates in sea ice. This sediment can provide clues about ice-age processes and help researchers understand why and when the ice ages begin, stop, or accelerate.
They have also used a satellite called GRACE to measure the change in the mass of the ice sheets as they melt and regrow. This information is directly related to the changes in the size and location of the ice sheet surfaces, which can in turn be linked to the climatic events that trigger the ice ages.
What they have learned is that during the ice ages, Earth’s temperature is driven primarily by changes in the distribution of water. The ice sheets increase Earth’s reflectivity, so the surface absorbs less sunlight and cools. As the ice grows it further increases Earth’s reflectivity, and the cycle continues.
The ice ages also seem to occur in a regular pattern, about every 100,000 years. This may have something to do with the elliptical orbit of Earth around the Sun, which causes variations in the amount of light it receives. Other factors are less clear, such as long-term fluctuations in the Sun’s output and shorter cycles like sunspot activity.
If we were to experience another ice age, it would have significant implications for human civilization. Huge regions where millions of people live today would be covered with a thick layer of ice and inaccessible. But we can avoid an ice age by reducing our use of fossil fuels and by restoring natural ecosystems. It’s never too late to make a difference.