February 27, 2007

Understanding the Science Behind Carbon Neutrality

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Despite President David Skorton’s recent signing of the Presidents Climate Commitment to a climate-neutral campus, the meaning of climate and carbon neutrality is not always clear.

A climate-neutral campus would ideally emit zero net greenhouse gases. Carbon neutrality is closely related to climate-neutrality and entails zero net carbon dioxide emissions.

There are several ways to achieve carbon neutrality, according to Prof. Arthur DeGaetano, earth and atmospheric sciences and director of the Northeast Regional Climate Center.

“The first way is switching to an energy source that doesn’t involve emitting carbon dioxide,” DeGaetano said, listing solar, wind and geothermal energies as clean alternatives to fossil fuels.

“Alternative energies should be the popular way,” said Prof. Joseph Yavitt, natural resources. “There’s a tremendous amount of solar energy coming down.”

However, both DeGaetano and Yavitt admit that such alternative energies will be difficult to implement in the short run.

“The very large power demand of the University will preclude wind and solar [power] being a high proportion of the approach,” said Prof. Timothy Fahey, natural resources.

Fahey was involved in writing the internal “white paper” which advised Skorton on climate neutrality and related energy issues.

“One relatively cost-effective option for power generation would be biomass fuels, wood or grass crops; these can be nearly carbon neutral for combusted power and actually carbon negative if accompanied by carbon capture,” Fahey said.

Unlike fossil fuels, which release carbon dioxide that was once trapped in the ground, the carbon in biomass fuels is extracted from the atmosphere as the plant grows. Burning the plant releases carbon dioxide, but the net gain to the atmosphere is nearly zero.

Another possible avenue to neutrality is carbon trading.

“The same type of thing is in place with [the Kyoto protocol],” DeGaetano said.

Under the Kyoto Protocol, participating nations that produce more than the maximum level of carbon dioxide can buy credit from nations that are more efficient and are below their allotted emission level.

A similar trading system can apply on a smaller scale to institutions like Cornell, or even individuals, who would purchase carbon offsets from companies that remove carbon from the atmosphere, according to Yavitt.

“The market-based approach worked extremely well for reducing sulfur emissions. But in that case the sources of emission were very well known and easy to police,” Yavitt said.

He added that for individuals purchasing carbon offsets, “it is in the market’s interest to be credible and make sure you get what you’re paying for.”

“Many schools signing the pledge are talking about buying carbon offset credits,” said Fahey. “Although this may become part of [Cornell’s] strategy, we didn’t think this was a good option in the short run.”

Fahey described other options that the University will be pursuing, which include “increased efficiencies in a variety of operations, changes in fuel mixes for power generation and pre- or post-combustion carbon capture and storage.”

He also added that “transportation systems will likely get attention, as commuting is regarded as part of campus operations.”

“Conceivably, Cornell might try to develop some way to actively remove carbon from the atmosphere,” DeGaetano said. “We probably need to reduce global atmospheric carbon dioxide emissions by 50 to 60 percent to have manageable climate change.”

Yavitt suggested a similar approach, using Cornell’s strengths to tackle the problem. “It can be entrepreneurial and stimulate creativity … to see if you can design something that can take CO2 out and be economically feasible.”

“Carbon neutrality is a first step,” Yavitt added. “But we should be looking toward bringing the levels down.”

He also emphasized that carbon dioxide is not the only greenhouse gas, and that methane levels in the atmosphere seem to be even more closely correlated with temperature than carbon dioxide.

Human activity has more than doubled atmospheric methane in the past century, notably through natural gas production.

“Although in the global scheme, Cornell is a drop in the bucket, [the climate neutrality commitment] does send a powerful message that we can hope will trickle up,” DeGaetano said.

Skorton alluded to the broader influence of Cornell’s commitment in a press release last Friday, which stated, “We will use our leadership opportunity to encourage more public and private investments in investigations that will yield better understanding of the underlying science and, therefore, better approaches to the problems. By signing the Presidents Climate Commitment, Cornell is embarking on an important journey to do its part to address global climate change and to make American campuses more sustainable. By working together, we can make a difference for Cornell and for the world at large.”