ORNL is marshaling talent for one of humankind's most important studies.
"Most scientists viewing the accelerated burning of fossil fuels now agree that excess CO2 will warm the earth's surface temperature significantly… Clearly it is necessary to foresee more accurately the consequences of the continued use of fossil fuels…"
During the 30 years since three Oak Ridge National Laboratory scientists helped pen this paper examining evidence of climate change, many of the same questions remain regarding how the unseen remnants of the world's growing dependence on fossil fuels have affected and may continue to affect the planet for generations to come. Humans are, in fact, performing an inadvertent experiment on Earth that is increasing the concentration of CO2 in the atmosphere well beyond historic levels. The result is a growing collection of data that indicates sustained climate change for the future.
Since 1976, the symptoms of global climate change have become more evident. The Intergovernmental Panel on Climate Change Fourth Assessment, issued in 2007, reported that the average temperature worldwide has risen by more than 0.7°C over the past 100 years. Eleven of the past 12 years are among the warmest on record since 1850. As ice sheets and sea ice thin, sea levels are rising by 1.8 millimeters per year. Snow cover in the northern hemisphere has declined by about 10% since the 1960s as mountain glaciers retreat. Meanwhile, weather patterns have shifted significantly, resulting in torrents of rain on some parts of the world while other regions have experienced prolonged periods of drought.
While some long-term assumptions about climate change remain inconclusive, a growing volume of scientific and anecdotal evidence has become a central topic of discussion among scientists, industry, policymakers and the general public. Energy giants such as BP, Chevron and Exxon Mobil are now advocates of greenhouse emission cutbacks and energy consumption control measures. Long-time skeptics of nuclear power as an alternative to CO2-emitting coal-fired plants have reversed their position. As climate researchers fill in the missing pieces of data, public polls reflect a growing belief that climate change is real and should be addressed, although precisely how is unclear to many.
Many elected officials are understandably demanding that climate researchers provide concrete answers, given the immense economic and social costs required to mitigate climate change or to adapt to projected consequences of sustained warming. Forecasts of climate change, although improving, still strive for greater accuracy and detail regarding what impacts will occur, where they will occur, how severe they will be, and how fast they might occur. Earth's complex biological, environmental and socioeconomic systems often reveal their secrets hesitantly. The challenge for the scientist is to understand these highly complicated systems and represent their complexity accurately and dispassionately.
In at least one important respect, climate change is an energy issue. The large majority of scientists agree that CO2 derived from fossil fuel use is a primary forcing factor in global warming. Increasing CO2 concentrations in the atmosphere cause more of the sun's radiation entering the atmosphere to be trapped, creating the "greenhouse" effect. Increasingly, researchers are addressing questions regarding the precise interactions among emissions, the atmospheric chemistry and the capacity of terrestrial ecosystems and oceans to take up atmospheric CO2. A further challenge is to address other atmospheric components such as aerosols that can create a cooling effect. Resolving these and other questions requires that climate scientists measure, experiment and model this complex system with tools that have become available only in the last few years.
After early evidence several decades ago from the Hawaiian Mauna Loa CO2 monitoring record demonstrated consistently increasing levels of carbon dioxide in the atmosphere, researchers at ORNL and elsewhere began their climate-related research with the simple quest to track the carbon—where the emissions were coming from, where they were going and how much ended up in the atmosphere.
"Originally, we called this the missing carbon," says Gary Jacobs, who heads up ORNL's environmental research efforts. "We could measure and estimate what was in the atmosphere, and we had a handle on the global emissions. The difference in the two had to be the carbon dioxide that was being taken up by terrestrial ecosystems and oceans. Our challenge has been to quantify those values and understand how they might be changing over time.
"This question evolved into one of how increased amounts of carbon dioxide in the atmosphere would affect ecosystems that provide valuable resources—food, fiber, fuel, recreation— to Earth's inhabitants and how their dynamics would affect the amount of CO2 and other greenhouse gases in the atmosphere. In experiments, researchers must examine CO2 as a source of change by itself and link the greenhouse gas with the expected results of global warming—higher temperatures and altered rainfall patterns.
"Clearly it is necessary to foresee more accurately the consequences of the continued use of fossil fuels by: 1) learning more of the carbon cycle…; 2)most importantly, learning more about the climatic (particularly regional) effects of increased atmospheric CO2 through a greatly increased and integrated climate study effort; and 3) learning how to predict the full impact of a given change in regional climate on man, (the) environment and … society."
The scientific community is working to answer these questions through the multi-agency U.S. Climate Change Science Program. The Department of Energy hosts research on the integration of atmospheric science, carbon cycle science, ecosystem dynamics, climate change prediction and integrated assessment. ORNL's contribution through DOE as well as a number of other federal agencies has focused upon the terrestrial carbon cycle, ecosystem response to environmental change, associated data archiving, climate change prediction and assessments of impacts, mitigation options and adaptation strategies.
For more than a decade, ORNL has served as a repository and resource for climate change data, storing information that includes carbon dioxide measurements from around the world, ground-truth data for NASA's satellite observations and an archive that offers clues to how climate will change cloud formation and precipitation patterns. ORNL researchers have studied ecosystems and population centers to determine the impacts of human-induced climate change as well as the ways humans could potentially respond to predicted changes in their environment. In addition to the studies of cause and adaptation, another group of ORNL scientists is examining mitigation strategies such as planting bioenergy crops that could counter to some extent the fossil fuel emissions that humans are pumping into the atmosphere.
The intensified research of the past 30 years has led a majority of scientists to agree that climate change is occurring, attributable largely to a geometric increase in greenhouse gas emissions. Still, a number of important questions remain regarding how climate changes from year to year, how fast future changes will occur and how society can best respond to these predicted changes.
Today's scientists have new measurement tools and computational capacity that were not imaginable in the early 1970s. New sensors and sensor networks will enable researchers to undertake a more sophisticated process of monitoring the environment and set up single- and multi-factor experiments to test the assumptions that accompany potential climate changes. Meanwhile, leaps forward in genetics and genomics are helping ORNL researchers to design groundbreaking studies of ecosystems at a molecular level, viewing how the genes of plants respond over time to changing atmospheres and environments.
ORNL's investment in high-performance computing has positioned the Laboratory to become a world leader in climate modeling and visualization. By the end of 2008, the Laboratory will be home to two of the world's largest supercomputers, one funded by the Department of Energy, the other by the National Science Foundation, and both with the capacity to bring new research options to the climate change discussion.
Thomas Zacharia, ORNL's director of computing and computational sciences, says: "With the world's second fastest supercomputer already available at the Laboratory, we have performed studies that project the level of emissions over the next century that would be required to limit global warming to 2°C. As the computer's power expands to a petaflop—that is, 1,000 trillion calculations per second—by 2009, the regional details of climate impacts and key feedbacks with clouds and ecosystems will be available.
"ORNL's climate change program includes a growing focus on understanding how new technologies might aid in adaptation to the realities of climate change. ORNL Corporate Fellow Tom Wilbanks served as a coordinating lead author of a chapter in the 2007 Intergovernmental Panel on Climate Change Fourth Assessment report discussing the potential impacts of global climate change on settlements and society.
The Laboratory's adaptation research is complemented by similar efforts to mitigate the nation's carbon dioxide emissions and develop more sustainable energy sources. An ORNL-led team recently was awarded one of three new $125 million Department of Energy bioenergy research centers. The Laboratory is also a leader in the development of energy efficiency technologies for transportation and buildings that could help lessen the growing demand for Earth's finite resources.
"The urgency which we sense from the present study is that decisions of the next few years may block or put off humanity's choices for avoiding drastic changes in the early or middle decades of the 21st century."
In addition to a variety of environmental and societal impacts, climate change has emerged as a question of national security. ORNL's National Security Directorate recently initiated a project, supported by the Department of Homeland Security, that considers questions raised by prospects of severe environmental events and ways that large and small population centers can prepare for and respond to potential risks.
"We are examining what the literature says about the dimensions of community resilience to natural disaster, and with that understanding we are going to work with three cities as prototypes to see what is necessary to make them more resilient to natural disaster," Wilbanks says. "To me, that is a contribution to climate change research.
"On the experimental front, Jacobs says the Laboratory is planning to expand from small, single factor, manipulated experiments to larger areas that better represent existing ecosystems to determine how they respond to higher temperatures, altered rainfall and increased levels of carbon dioxide.
"We are in the process of defining from a climate change perspective the world's six to 12 most important ecosystems," he says. "Experiments in those ecosystems would enable us to begin to isolate the various factors such as temperature versus CO2 versus precipitation. We could then answer questions such as, how do these factors influence insect populations? How does the microbial community respond and influence ecosystem function and sequester CO2?"
The 34,000-acre Oak Ridge Reservation is an important resource for much of this research. Recently the reservation was designated a core site for one node of the National Science Foundation's National Ecological Observatory Network or NEON. The network will provide intense and consistent observations of ecosystems across 20 domains in the United States.
"Our research at ORNL," Jacobs says, "does not have to make the tough decisions or set policy. Our task is to provide accurate and unbiased information to the people who have to deal with one of the most complex subjects of our time. The job is even more difficult because the science at times is uncertain, often making it impossible to provide black and white answers as quickly as some would like. Our challenge is to make dramatic strides in understanding the future impacts of climate change. Armed with that understanding, we can then help design mitigation and adaptation strategies for the next generation."—Larisa Brass
Contact: Gary K. Jacobs
Photo 1 Rich Norby, Christopher Schadt, Aimee Classen, Hector Castro Gonzalez
Photo 2 Lianhong Gu
Photo 3 David Weston
Photo 4 Gregg Marland
Web site provided by Oak Ridge National Laboratory's Communications and External Relations