Predictions from the Ice

How would you like to take a trip with me in a glacial time machine? For the last two and a half million years, earth's climate has been switching between cold times known as glacials and warmer times known as interglacials. During the glacials, an ice sheet or glacier covered much of Canada, the northern United States and Northern Europe. During the interglacials, the ice sheets melted and became smaller and many disappeared. In some places, like Greenland and Antarctica, the ice sheets didn't completely melt during the interglacials. And because they didn't melt, they contain a record that goes back 700 to 800,000 years ago. What do ice cores reveal about climate changes? Ice core records show that earth's climate has been going through a cycle from coal to warm and back to cold, approximately every 100,000 years. The ice cores also show that the levels of carbon dioxide and methane also change regularly about every 100,000 years. The amounts of methane and carbon dioxide are at high levels when the climate was warm and low levels when the climate was cold. Carbon dioxide and methane are known as greenhouse gases because they help to warm the Earth's atmosphere. So it makes sense that as the amounts of greenhouse gases goes up and down, the temperature also goes up and down. During these warmer periods, the level of greenhouse gases never rose above a certain amount. Hundreds of thousands of years ago, people had no influence on the levels of greenhouse gases. So we know that the levels that occurred during those warmer periods occurred naturally. However, the ice core records show that about 200 years ago, the levels of greenhouse gases in the atmosphere began rising much higher than anything we'd seen before. This has led scientists to question the sources of this extra carbon dioxide and methane in the atmosphere. How are carbon dioxide and methane produced? A major source of carbon dioxide to the atmosphere is when humans burn fossil fuels, such as coal, oil, and natural gas. Methane is added to the atmosphere in a few different ways. Natural sources include termites, wood fires, and bacteria in wetlands. Methane is also released when humans grow rice and rice paddies and raise cattle and sheep. It also comes from our landfills. As the trash we put into our landfills begins to break down, methane is created. More than half of the methane released into the atmosphere each year comes from human sources. Over the last 200 years, as the levels of greenhouse gases have been rising, records indicate that earth's climate has also been warming. Again, we can see the link between the levels of greenhouse gases and earth's global temperature as recorded in the ice cores for the past 700,000 years. What can ice cores reveal about the future? If our time machine could take us 200 years into the future, what do you think we would find? Well, earth's climate be warmer or colder. Will there be any ice cores in the future for scientists to study? As you can see from our travels to the past and into the future, the information found in ice cores help scientists understand what earth's climate has been like over the past hundreds and thousands of years. This information gives them clues as to what earth's climate might be like in the future. I hope you enjoyed our travels and thanks for coming along.