Climate change. We know it’s happening, but how much of an exception is it from the normal cycles of the Earth’s cooling and warming? Now, a meta-study by scientists including Shaun Marcott, a post-doctoral researcher at OSU’s College of Earth, Ocean, and Atmospheric Sciences, has provided a background of 11,000 years of climate data. The former picture only covered the past 2,000 years, primarily using data from tree rings. Most people are only aware of the so-called “hockey stick” climate change data, which shows 1,000 years of small ups and downs in temperature spiking up dramatically in the past century.
“As far as we know, no one else has done this,” said Marcott. “We were sort of surprised that no one had tried to put together this global picture.”
Published last month in the journal Science, Marcott’s study compiled data from more than 70 sources. Most of the data originated from ocean sediment cores made up of fossils of planktonic foraminifera, tiny organisms whose calcium carbonate shells drop down to the ocean floor when they die. These fossils can be used to determine the temperature of the Earth when the organisms lived.
“When they die their body erodes but this shell is left over. It piles up in the sediments,” said Marcott. “You can get a nice record of temperature from the chemistry of their shells.”
Marcott spent the better part of his doctorate assembling the data sets and putting together a global picture of temperatures over the past 11,000 years.
“What we found was starting from about 8,000 to 5,000 or 6,000 [years ago] the global climate seemed pretty stable. It was about as warm as it was today. Beginning about 5,000 years ago, it appeared that global temperature began to cool, up until about 300 to 200 years ago, and then it reached its maximum amount of cooling and then, based on the instrumental record, temperatures began to warm.”
Most notably, this recent warming covers the full temperature range experienced over the past 11,000 years.
“In a hundred years we’ve gone from the cold end of the spectrum to the warm end of the spectrum,” said Marcott. “We can’t say if this is unprecedented, but it gives us some perspective. Whatever’s going on today, we’ve seen the full spectrum of temperatures that essentially took 11,000 years to create.”
Marcott’s study does not say anything about how rare it is for temperatures to spike as suddenly as they have; it’s unknown whether the warming in the past century is the only time when temperatures have changed as rapidly. But we do know that it’s a spike from the very lowest temperatures the Earth has seen in the past 11,000 years to the highest—all in a mere 100 years.
This geological context also gives scientists a hint of where in the past to look for information about where we’re headed. Studying the conditions on Earth 8,000 years ago—when it was as warm as it is today—may provide hints about what we’ll see in terms of sea ice, distribution of life, and other factors.
Whether you believe that carbon emissions might save us all from an ice age (as do researchers at the University of Gothenburg in Sweden) or end up eradicating most life on Earth (ask the next person you run into in Corvallis), there is no doubt that the Earth is warming, and that human activity is to blame.
Whatever happens, it’ll be big. The Intergovernmental Panel on Climate Change has created several possible scenarios of the Earth’s climate in 2100. Every single one of them shows a warmer Earth than has occurred in the past 11,000 years.
“It’s a pretty intimidating problem; it’s going to take some pretty smart people to figure it out,” Marcott said.
The Ethics of Climate Change
If you’re interested in the greater implications of climate change, pick up a copy of Moral Ground: Ethical Action for a Planet in Peril. Co-edited by Kathleen Dean Moore, distinguished professor of philosophy at Oregon State University, the series of essays discusses how stopping global warming is a moral imperative—not just a scientific one.
From the essay Africa Must Be Heard on Climate Change by Wangari Maathai: “Unless we change course, the coming generations will inherit an impoverished environment that will mean a hungrier, less fertile, and more unstable world. We have a responsibility to protect the rights of generations, of all species, that cannot speak for themselves today.”
by Jen Matteis