SPRING PERSPECTIVE -2005
The case for staving off climate change
Does global climate change concern you? Are you convinced it’s worth considering?
If you answered no to either question, Paul Shepson hopes well-communicated science will overcome your perception – a perception he says is dangerously common in the United States.
Shepson says he hopes to garner his fellow scientists’ help in publicly explaining climate change and its likely consequences if allowed to continue unabated.
With a dual professorship in chemistry and earth and atmospheric sciences, Shepson has led Purdue’s Climate Change Research Center since it was founded in April 2004.
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The center’s mission is to bring together erudite research faculty and other resources from all Purdue schools and colleges to further quantify and explain how and why the earth’s climate is gradually getting warmer, what people have been doing to accelerate the change, what consequences it will likely have on all living things, and what should be done about it.
Beyond that, the center is studying how to effectively communicate the science of climate change to the segment of the public that is skeptical, unconcerned, or simply unaware.
Center researchers are paying particular attention to the regional effects of global climate change, examples of which include changes in growing season durations, species diversity loss, changes in pest populations, and changes in precipitation, all of which can threaten the agricultural industry and the food supply.
"Although global change is happening," Shepson says, "effects of climate change are felt regionally. We want to link global climate change to Midwest and other regional-scale issues. We want to provide feedback to the agricultural community – to predict changes in patterns of precipitation, freezes and thaws."
Pausing, Shepson cautions that the terms "climate" and "weather" not be confused: "Weather and climate are about totally different things. Climate is about change in the frequency and patterns of weather over years to decades to centuries. Weather is measured in events that occur over a matter of days. You can’t tie any one weather event to climate change."
Hence, a few days of unusually extreme heat during a Midwestern summer or an oddly mild New Year’s Day in the North-west should not be seen as indicative of the far larger, much broader phenomenon of climate change.
"To study climate change we look at years of existing data; we look at the fossil records," he says, scratching the surface of the complex science.
Shepson says available scientific data makes clear that large-scale industrial practices during the past 150 years have significantly increased concentrations of greenhouse gases in the earth’s atmosphere. The growing concentration of these gases retains heat that is radiated up from the planet’s surface into the atmosphere, effectively trapping that heat and causing a gradual rise in the earth’s temperature.
"In the past 100 years the global average surface temperature has increased by about 0.6 degrees Celsius," Shepson says. "Although 0.6 degrees is hard for the average person to feel and understand, the impacts of this global temperature change are serious and expected to continue at an increased rate of warming."
Scientists generally agree that during the past 20 years, about three-quarters of human-made carbon dioxide emissions, a significant greenhouse gas, resulted from burning fossil fuels such as coal, oil or natural gas.
Persuading a skeptical or inattentive public
Arguably as challenging as discerning all the factors affecting current and future climate change is communicating about it.
One of the central thrusts of the Purdue Climate Change Research Center is its educational mission.
Shepson says he isn’t surprised that a significant portion of the U.S. population is skeptical about global warming.
"The media and the public can’t do peer review," he says, referring to the practice through which scientists evaluate each others’ research and opinions. "The average person isn’t equipped to make an evaluation about whether or not the sources quoted by the media are credible.
"And stories that relate to climate change being a hoax are entertaining; unfortunately, much of the media is about entertainment, not presentation of accurate information."
PCCRC’s education mission encompasses education at all levels from elementary through graduate school, but also education of the general public and public policymakers.
Leigh Raymond, assistant professor of political science, is associate director of the center in part for this reason.
Raymond’s involvement with the center is basic to the center’s mission "to the degree that one wants to apply scientific knowledge in a way that is helpful to policymakers," he says. "I study environmental policy, and it’s agreed by all sides that one of the most important issues is the need to integrate scientists and scientific knowledge into the policy process.
"You don’t want to let this good science go to waste, so you must make it politically relevant and useful."
Raymond says one fairly prevalent public misconception suggests that existing scientific knowledge about climate change is essentially guesswork. Apart from being inaccurate, it’s missing the point, Raymond says.
"The point is that we must make the best decisions that we can with the information that we have," he says. "The problem is that in the policy world we have to make decisions under some uncertainty every day."
Another challenge for the center, Shepson says, is encouraging the public and policymakers to solve the problem of climate change even though many of its negative consequences will be felt only over relatively long periods of time.
"There is an enormous challenge in dealing with the disconnect between the time scale for decision-making and the time scale for climate change," Shepson says. "Decisions within industry and the political arena are made quarterly to every four years, while climate changes occur on the scale of decades."
Shepson says the U.S. public and its leaders, more so than the European community, aren’t yet convinced that climate change is a critical enough problem to require solutions such as reducing fossil fuel burning.
"Why should we care?" he asks. "Because within decades, climate change will affect coastal flooding, the spread of disease through disease-carrying pests, the cost of food and the viability of a wide range of species, such as Arctic mammals that rely on the existence of a frozen Arctic Ocean. We need to be able to understand, prepare and adapt."
If those reasons aren’t compelling enough, Shepson argues his point on fundamental economic grounds: "If we continue to hide from reality and other countries are successful in pursuing other environmentally responsible forms of energy, ultimately they’ll end up with the wealth."
Tens of thousands of years can be a relatively short period of time
A study by Matthew Huber, assistant professor of earth and atmospheric science, in collaboration with other scientists from around the world, illustrates the often-dramatic depth and breadth of climate change research.
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Published in the December 2004 issue of the scientific journal Paleoceanography, the study tosses a broadly accepted climate theory on its head by suggesting that the mile-thick ice sheet covering Antarctica may not have developed because of a shift in ocean currents millions of years ago, as commonly believed.
Instead, Huber and his collaborators from Sweden, Canada, the Netherlands, the United Kingdom as well as the United States, report evidence that indicates a shift in greenhouse gases – not ocean currents – may have been the cause.
Though climate scientists have theorized for decades that warm, tropical currents flowed poleward toward Antarctica, keeping Antarctica largely ice-free during the Eocene epoch before 35 million years ago, a series of deep-sea core samples taken recently from the ocean floor south of Australia calls that theory into question.
The samples, which were deposited while Australia and Antarctica were beginning to drift apart, show that the fossils of cold-
loving plankton life forms were common in the waters east of the two then-adjacent
continents.
"These fossils indicate that a cold current, not the warm one that has been theorized, was flowing past the Antarctic coast for millions of years before the ice sheet developed. Indeed, the current must have been flowing toward the equator, opposite to the direction previously believed," says Huber, the study’s lead author. "Nevertheless, the ice sheet appeared very rapidly, over a period of just a few tens of thousands of years. Some other factor must have caused the rapid cooling that allowed it to form in the absence of a major current change."
Eocene records also show that substantial changes in the planetary carbon cycle – the complex series of reactions by which carbon passes through the earth and its atmosphere – occurred at exactly the time that the ice sheet developed. Huber says the most justifiable explanation for the development of the ice sheet was a massive change in atmospheric greenhouse gas concentrations.
"In light of all these data, a change in carbon dioxide levels in the atmosphere is a more reasonable explanation for the rapid icing of the Antarctic continent," he says. "Given the apparent sensitivity of Antarctic ice to greenhouse gases, it should give us pause that today humans are effecting changes in the amount of carbon dioxide in the planet’s atmosphere."
Huber acknowledges that his team’s work will provoke controversy but also cautions that its conclusions are suggestive, but not yet definitive.
Some current PCCRC projects
-- Observing and modeling the effects of climate change on agricultural yields and water use in soybean and maize crops.
-- Optimizing climate model information for agricultural forecasting and decision-making.
-- Predicting ultraviolet light exposure for pedestrians in urban areas.
-- Quantifying the direct and indirect effects of aerosols on climate.
-- Studying current and historical cycles of greenhouse gases through the earth and its atmosphere.
-- Studying the political economy of climate change, including the effectiveness of market-based environmental policies related to
emissions.
-- Exploring alternative energy production, transportation, construction materials and practices, and carbon sequestration.
To learn more about PCCRC, visit its Web site: www.esei.purdue.edu/pccrc/.
Stories by Chad Boutin, Purdue News Service, and Amy Raley
Photograph by Tom Campbell, Agricultural Communication
Paul Shepson poses with the Beechcraft Duchess light twin engine airplane used by Purdue’s Airborne Laboratory for Atmospheric Research (ALAR). Funded by the National Science Foundation’s Biocomplexity in the Environment program and the Showalter Trust, the ALAR uses the aircraft to conduct measurements of volatile organic compounds in the atmosphere. Soon Shepson and other faculty and graduate students who work with the ALAR will be able to conduct measurements of ozone and reactive nitrogen oxides.
This image, based on newly obtained core samples from the ocean floor near Australia and Antarctica, shows a revised conception of current flow past those continents around 33 million years ago. At that time, the continents were just beginning to drift apart, and scientists have theorized that a warm-water current flowing southward along the Australian coast reached Antarctica, keeping that continent largely ice-free. But fossil plankton in the core samples indicate that a cold current flowed past Antarctica for about two million years before the continent developed its mile-thick ice cap, suggesting that the ice formed as a result of some other mechanism – possibly a variation in greenhouse gases in the ancient atmosphere. (Purdue University graphic/Huber laboratory)
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