In April 2008, atmospheric scientist Kevin Gurney and several colleagues from Purdue, Colorado State University, and Lawrence Berkeley National Laboratory published the first detailed inventory of carbon dioxide emissions from the burning of fossil fuels across the United States. Known as the Vulcan Project, for the Roman god of fire, the inventory catalogues how much carbon dioxide different human activities produce on an hourly, daily, and monthly basis—from vehicles to industrial activity to electricity used by homes or businesses.
Prior to the Vulcan Project, most estimates of fossil fuel emissions were based on population density as a stand-in for actual measurements. “We had annual estimates at the national level, which you can get from basic UN [United Nations] statistics derived from sales of coal, oil, and natural gas around the world. But people would distribute them within a country based on population density,” said Gurney.
In contrast, Gurney and his team tallied up emissions from specific human activities where they actually occur and summarized them by city, county, and state. Sponsored by NASA and the Department of Energy as part of the North American Carbon Program, the inventory will help advance carbon cycle science and could help the United States as it develops strategies for reducing the carbon dioxide emissions that are driving global warming.
The Need for a Better Inventory
The project evolved as a sideline from Gurney’s research on the natural carbon cycle and the mystery of the “missing carbon sink.” The mystery is that atmospheric carbon dioxide levels in the Northern Hemisphere are lower than scientists would expect given the amount of fossil fuels we burn. Somewhere, there is a missing carbon sink, a place or places that are taking in more carbon dioxide than scientists expected.
A few years ago, NASA began firming up its plans to launch the Orbiting Carbon Observatory (“OCO” for short) satellite in late 2008 or 2009. OCO will provide the smaller scale, more frequent measurements of carbon dioxide in the atmosphere that scientists need to pinpoint the Northern Hemisphere’s missing carbon sink. It was at this point that Gurney got sidetracked by the fossil fuel inventory.
“When NASA began talking about its plans for OCO,” he says, “we thought, ‘OK, we are going to have the observations of CO2 in the atmosphere at smaller scale, but now we have a big looming problem, which is we just don’t know fossil fuel emissions well enough at that scale.” In other words, scientists would have more detail on where carbon dioxide winds up, but still not enough detail about where it came from.
A demand for more detail on emissions also began to emerge from the community of people thinking about energy policy and emission regulation. “A decade ago,” says Gurney, “the policy community was thinking in very broad terms about emissions mitigation at a national level.” But in recent years, policymakers on the state and local level have become increasingly interested in reducing their carbon footprint through locally tailored strategies. These science and policy needs motivated Gurney to propose Vulcan.
Making the Data You Have into the Data You Need
To create the inventory, Gurney and his colleagues relied on existing data at numerous state and federal agencies, including the Environmental Protection Agency, the Federal Highway Administration, and the Census Bureau. Nobody specifically collected data on carbon dioxide emissions, but they each collected data that could be fed into models that would allow Gurney to estimate them.
The EPA had data on how much carbon monoxide industries, power plants, or urban areas generate; what kinds of devices produced it, and the kind and amount of fuel they used. Knowing all these things, says Gurney, “I can figure out how much CO2 was emitted quite easily with simple combustion models.”
In addition to pollution records, they used county records of everything from the square footage of commercial and residential buildings, to the miles of roads, to how many and what kinds of cars were registered. They gathered these records up, figured out how to tease carbon dioxide emissions from them, and mapped them on a common grid.
Stories of American Energy Use
Even the preliminary analysis he has done with Vulcan so far fascinates him. As a case in point, he talks about ranking the top twenty counties with the highest emissions.
“The first thing you see,” says, Gurney, “is that virtually no part of the country is un-represented.” There are pockets of high emissions all over the country. And the counties with the highest emissions are often, but not always, places with large populations. In some cases, a busy interstate highway through a mostly rural area or a power plant that supplies electricity to other counties (even other states) is enough to push a county up in the rankings.
Even in counties with similarly high population densities, the processes causing high emissions aren’t always the same. “Consider the top three counties,” says Gurney. The first encompasses the Houston area, the second, Los Angeles, and the third, Chicago. On the one hand, it isn’t a surprise that such densely populated places make the list of the largest emitters in the country. On the other hand, Gurney finds it interesting that they each have different reasons for being there.
“Around Houston, it’s industrial emissions that pushes them to the top of the list. In Los Angeles, it’s cars. In Chicago, it’s residential and commercial heating—because the temperatures are cold and the houses and buildings are old.”
To Gurney, the inventory isn’t about calling places out for bad or good carbon behavior. “It’s really a story about American life, about how people live in different parts of the country, what their energy needs are and how they meet them.” This story is fundamental to deciding the most effective and realistic strategies for reducing emissions that cause global warming.
Some stories appear straightforward and predictable. A graph of daily carbon dioxide emissions traces out the American work week: emissions are consistently higher Monday through Friday, dropping on Saturday and again on Sunday, as the population takes a rest day.
Other stories appear simple on the surface, but could have multiple underlying themes. Tallying up emissions on a weekly basis over the course of a year reveals a distinct summer time peak. Scientists will have to analyze the inventory more carefully to determine the reasons for the seasonal patterns. Is it because, as a nation, we use more electricity to cool our homes and businesses than to heat them? Or is it that we travel more in summer?
Having the data to start to answer these questions has given Gurney new enthusiasm for the project. “We have devoted so much time to building the system and all the tedium that goes with it, and now we get to do exciting stuff. I am really more excited about the project now than I was at the beginning,” he says.
From Vulcan to Hestia: A “Science 2.0” Test Case?
Gurney is also intrigued with the potential for the Vulcan project to explore questions that fall more under the domain of social, as opposed to physical, science. Among them, how might scientists use the Web to tap local expertise to expand on or quality-control science data sets? When his group announced the release of the Vulcan inventory, they created a Website where they solicited collaborators. Dozens of people, from environmental groups to employees of state and local regulatory agencies, contacted Gurney through the Website, sharing data and local expertise that may improve the inventory’s quality.
Gurney admits that the “Science 2.0” approach (using wikis, blogs, and other Web 2.0 technologies to allow easy, global-scale collaboration) has its limitations, and isn’t suitable for all kinds of science—”Obviously, you couldn’t do high-energy physics this way”—but it’s something he wants to explore.
That kind of approach will likely play a big part in the next phase of his project, which his team is calling Hestia, after the ancient Greek goddess of the hearth. The team plans to find partners in industry, government, non-governmental organizations, and universities around the world to create a global fossil fuel inventory that drills down to the scale of urban neighborhoods. Anyone on the Web will be able to access it through an interactive, three-dimensional visualization of the Earth.
With a project so ambitious, they’ll need all the collaborators the Web can bring them.