Geologists Chris von der Borch and Dave Mrofka collect sediment samples in South Australia. These rocks hold clues to help explain why climate changed 635 million years ago.
Click on image for full size
Courtesy of Martin Kennedy, UCR
Scientists Search for the Cause of Ancient Global Warming
News story originally written on May 28, 2008
Earth’s climate is warming quickly now. We know that this has to do with additional greenhouse gases in the atmosphere and other global changes. But there is a lot we don’t yet know about how warming will affect our planet. How could we know? We’ve never been through this before, have we?
Actually, even through we humans have never experienced fast global warming, our planet has. And our planet keeps records of what happened. The oldest records that the Earth keeps are in its rocks.
Looking through those records of our planet, geologist Martin Kennedy searched for evidence of ancient climate changes in very old sedimentary rocks. He was interested in learning more how and why rapid global warming happened 635 million years ago.
Kennedy and two other scientists, David Mrofka and Chris von der Borch, collected hundreds of sediment samples from rocks in South Australia. Each sample of sediment was studied with stable isotope analysis, an important tool used to understand climates of the past.
"Our findings document an abrupt and catastrophic global warming that led from a very cold, seemingly stable climate state to a very warm, also stable, climate state--with no pause in between," said Kennedy.
Earth had been covered by a thick ice sheet for millions of years before the warming started 635 million years ago. Their research suggests that a little warming caused the ice sheets to collapse. This released a large amount of the greenhouse gas methane into the atmosphere, which had been in a frozen icy form under the ice sheets. The methane increased global warming rapidly.
Today, methane is in Arctic permafrost and beneath the oceans. Researchers believe that these sinks of methane will remain where they are unless triggered by global warming. It's possible that very little warming could unleash this trapped methane, which could warm the Earth tens of degrees.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, ranging from seismology
, rocks and minerals
, and Earth system science
You might also be interested in:
The climate where you live is called regional climate. It is the average weather in a place over more than thirty years. To describe the regional climate of a place, people often tell what the temperatures...more
Even though only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases, they have a huge effect on climate. There are several different types of greenhouse gases. The major ones are carbon...more
Isotopes are different "versions" of an element. All atoms of an element have the same number of protons. For example, all hydrogen atoms have one proton, all carbon atoms have 6 protons, and all uranium...more
For a glacier to develop, the amount of snow that falls must be more than the amount of snow that melts each year. This means that glaciers are only found in places where a large amount of snow falls each...more
Methane is a kind of gas. There is a small amount of methane in the air you breathe. A methane molecule has carbon and hydrogen atoms in it. Methane is a greenhouse gas. That means it helps make Earth...more
When the ground under your feet is frozen, interesting things can happen. The land may be covered with circles, polygons, or stripes, called patterned ground, which form as the land freezes. Trees may...more
Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. "The data will help give us a better road map to what a future...more