Crops vs. Forest? Land Use Models Predict Future Climate Change

“The land use choices we make can cause significant differences in our climate,” Gordon Bonan of the National Center for Atmospheric Research said to a crowded room in the Nicholas School, Thursday.

Depending on deforestation and agricultural expansion in the coming decades, the Earth’s climate will be impacted in various ways because different types of land cover interact with the environment differently.

Forests, in general, absorb large amounts of CO2 and solar radiation, and cool the air around them through evapo- transpiration. Cropland, on the other hand, is not as effective at capturing carbon.

However, cropland reflects sunlight better than some types of forest, raising an interesting question: is it more important to capture CO2, or to reflect sunlight and keep surface temperatures cooler? In other words, should forests with low reflectiveness be chopped down to make way for more-reflective fields? Some models say that higher reflectiveness and cooling that results from deforestation is more significant than warming caused by the increase in CO2. But a great deal of data is missing, and the debate is far from over.

Some things about climate change are clear: tropical rainforests, for example, are our “planetary salvation,” according to Bonan. They absorb a tremendous amount of carbon, but also cool the atmosphere and reflect heat. To mitigate climate change, major rainforest conservation and reforestation efforts must be undertaken.

Bonan and his colleagues at the National Center for Atmospheric Research work with computer models to predict future climate change. But Bonan’s talk, if anything, emphasized how uncertain climate models can be. The more factors that are included, such as land cover change, irrigation, and the carbon cycle, the more uncertainty there is bound to be. According to Bonan, there’s no clear way to model climate change that would result in any sort of consensus among the international scientific community.

However, consensus or not, Bonan and his colleagues are attempting to make their models as accurate as possible. Right now, their land use models “don’t account for diversity of crop types at all,” and assume a generic crop type for all cropland. Bonan hopes that a future model might be able to evaluate based on specific crop systems, such as soybeans, wheat, and corn.

Bonan’s team continually tests their model-generated hypotheses against observed data, collected at 15 sites spanning the globe. (Duke Forest is one of them.) “Experiments identify the shortcomings of a model,” Bonan said.

"Never say never again."

So many times, after genocide, people and governments say “never again.” But according to Homi Bhabha, the 2009 Andrew W. Mellon/FHI Distinguished Lecturer, “Ethically, even aesthetically, we will lose our way if we don’t believe that it will happen again.”

Bhabha, a professor of the humanities at Harvard University, spoke Tuesday at the Nasher about Time, Agency, and the Banality of Evil. “I know that a man can become of an extraordinary wickedness very suddenly,” Bhabha said.

Bhabha focused on the events that occurred in Rwanda in 1994, in which more than 500,000 Tutsis and Hutu political moderates were killed in just a hundred days. The total death toll stretched toward a million. In this instance, genocide was sponsored by the government, the subject of intense propaganda and professional organization.

Bhabha described how a major factor in genocide is the apparatus of “neighborly power,” whereby neighbors become enemies, and ordinary things become instruments of evil. In Rwanda, farming implements were repurposed for murder, and criminals could be called away from their task by the ring of a dinner bell, only to resume the killing later.

“The neighbor is the aim of obsessive, excessive violence,” Bhabha said. A neighbor is not strange, yet not quite close. Many times, not only are people killed, but any record of their existence is destroyed. Survivors must struggle with the fact that their family photo albums have been burned, their tapes and records ripped apart. It is just one facet of the “sudden, mysterious destruction of civic society.”

The pressures of popular participation is another factor. “The non-wicked everyone has no special motives, but is capable of infinite evil,” Bhabha said.

“When there has been one genocide in the world, there can be another one... if the cause is still there. And we do not know what the cause is.” Most importantly, he emphasized, “Never say never again.”

A Timely TED Topic

Dan Ariely, the James B. Duke Professor of Behavioral Economics in the Fuqua School of Business and a senior fellow in Duke's Kenan Institute for Ethics, has done some provocative research on the gray areas in which people feel just a teensy bit comfortable cheating. At the most recent TED conference, he wowed the invitation-only audience on this topic.

We profiled Dan about a year ago in Duke Research magazine here. His clippings, alas, would fill a very large web site!