A Conversation with
Scientist Ruth DeFries

Q: How did you feel when you learned you had been elected to the National Academy of Sciences?

DeFries: Stunned! It’s definitely an honor, but there are so many other people who deserve this honor. Certainly, it is very gratifying that research in the area of land cover and land use change is being recognized. It’s also a big responsibility.
Q: What do you mean?

DeFries: It’s an opportunity to raise the profile of land cover research, promote working with scientists from other fields, and develop dialogue with the policy community.

I also think [my election] shows that it is possible to do good science and still keep your personal priorities. I worked part time for many years when my children were young, because raising them was my priority.

Q: Can you tell us more about your work and your current research?

DeFries: I look at the role of land cover changes in climate, in terms of effects on the carbon cycle, as well as the implications for conservation and other services people derive from ecosystems. Satellite data allow us to see these changes.

What we are seeing in parts of the tropics is continuing deforestation, in many cases for large-scale conversion of land to mechanized agriculture. Land use change not only has repercussions for climate, but also for animal and human habitats that can include reduced biodiversity, loss of watershed protection and impacts on human health.

Of course, there is always a balance, or a trade off, between economic benefits of land use changes and the costs of these changes. Understanding the cost side of the equation requires not only measuring the immediate impacts of land use and land cover change, but also understanding climate and biological systems and how they are affected by these changes over longer periods of time.

Q: What do you think is the scientific consensus about climate change or global warming, as it is commonly called?

DeFries: There is a wide consensus that we are experiencing climate change and that it will accelerate in the future. The question is how human society will adapt to the changes that are occurring. Knowing how we need to adapt means that we need to understand the climate system so we can have the best, most accurate projections of the effects of climate change.

Q: What do you like best about what you do?

DeFries: I love working with students. Students are so creative and they really want to make a difference. And I love getting out in the field and really being able to see the changes on the ground and how people interact with their environment. —LT
 

Powerful CARMA Brings Cool,
Far Out Astrophysics More in Focus

Formed from a linked array of 15 radio telescope dishes perched high in the cool, dry desert of eastern California's Inyo Mountains, the Combined Array for Research in Millimeter-wave Astronomy, or CARMA, gives scientists unprecedented power to look across the universe (and back in time) to learn more about the birth of galaxies, stars, planets and even the universe itself.

“Most of what we know about the universe has come from optical or light-observing telescopes,” said University of Maryland astronomy professor Stuart Vogel, who chairs the science steering committee for CARMA. “However, each part of the electromagnetic spectrum opens new windows on the universe, and the millimeter-wave portion of the spectrum is the ticket for observing the universe's coldest matter, gas that is only tens of degrees above absolute zero.” “It turns out that planets, stars and even galaxies are assembled from this very cold gas,” says Vogel, who is director of the University of Maryland's Laboratory for Millimeter-wave Astronomy. “What’s special about CARMA is that it has the resolving power and sensitivity to observe this cold gas.”

Developing the CARMA site involved moving the nine 6-meter telescopes at the Berkeley-Illinois-Maryland Association array and the six 10-meter telescopes at Caltech's Owens Valley Radio Observatory to the higher elevation Cedar Flat location, and adding new, updated technology.

“We’ve recycled the two U.S. millimeter arrays to make a new telescope that is 10 times more powerful than what existed before,” says Vogel, who was a director of the Berkeley-Illinois-Maryland Association array prior to its incorporation into CARMA. “It’s hard to believe that after a decade of pushing, it's finally happened.” —LT

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