For decades, Linda Zall ’72, PhD ’76, led a project that produced a steady flow of scientific breakthroughs about climate change, helping to solidify evidence that human activity was causing the planet to heat up. But because it relied on top-secret images created by U.S. spy satellites, the project’s full scope was long classified—and until recent years Zall, a high-level CIA scientist, kept the extent of her role a closely guarded secret. “I couldn’t talk to anybody,” she recalls. “Sometimes things would leak and reporters would call CIA public affairs to talk to me, but I never would.”
Zall retired in 2013 but remained reluctant to talk about her work, until she began to realize that many of the scientists who had collaborated on the project were dying without ever having received the recognition they deserved. Says Zall: “I just felt the story needed to be told.” And so she’s been telling it—in a TV documentary that ran in Europe in early 2017, to a veteran New York Times science reporter who wrote a long profile of her this past January, and as part of an upcoming book (which, perhaps true to old habits, she declines to discuss in detail). Stepping forward has also led her to reflect on a long and exciting career that took her from Ithaca to Alaska, Washington to Moscow.
Zall grew up in Western New York, moving to Ithaca when she was in high school so her father, Robert Zall, PhD ’68 (later a professor of food science at Cornell), could pursue his doctoral studies. Her own time on the Hill, where she studied environmental systems engineering in CALS as an undergrad, coincided with a tumultuous period that included anti-war protests and the 1969 takeover of Willard Straight Hall. “Cornell was where I was exposed, for the first time, to ideas,” she recalls. “This was the Sixties, and I was a very sheltered, young Jewish girl. It was like an overload of the intellectual senses for someone like me, and it changed my life.”
Another transformative experience was taking an aerial photography class taught by engineering professor Donald Belcher, who had used the medium to locate choice sites for Brazil’s new capital city and for the Arecibo Observatory in Puerto Rico. The course, Zall says, spurred in her an “addiction to looking at the world from above.” She went on to do research under Belcher as a doctoral student in civil and environmental engineering, including aerial reconnaissance of the permafrost that informed construction of the Alaska Pipeline. Afterward, she took a job with the Earth Satellite Corporation (EarthSat), a Washington, D.C.-based company that was pioneering the use of commercial observation satellites. It was exciting, but Zall had a nagging sensation that she was missing out. “There was a section in my company that was working with the CIA,” she recalls. “I was never allowed in that part of the building, but I knew the people and I knew they were working on really cool things. They were working with satellites that were much better than what I was looking at—high resolution spy satellites. And the only way I could get my hands on them was to join the CIA. That’s why I joined—I wanted to look at the good stuff.”
Zall entered the agency in 1985, when the USSR was still its top concern. Her highly classified work would involve improving the CIA’s ability to watch Moscow from space and acting as a liaison to a secretive group of elite scientists, known by the code name JASON, that advises the U.S. government. But as the Soviet Union began to crumble, she took on a new mission—one that would prove more challenging, and more important, than anything she’d done before.
It began with a letter from Al Gore, then the junior senator from Tennessee. One of the first members of Congress to become alarmed about what was then known as “global warming,” Gore wrote to the CIA director in 1990 asking whether the agency’s satellite data could be used to study the changing climate. Its leadership was at first nonplussed; turning their fleet of powerful satellites on rainforests and polar ice caps made little sense to spies who were focused on keeping the Russians in check. But a U.S. senator couldn’t be ignored, so they passed the mission on to Zall. While she didn’t know much about climate change, she recalls, “I probably knew more than most people at the CIA—but I certainly wasn’t an expert.”
She soon became one, however—as the fall of the Soviet Union in 1991, and Gore’s election to the vice presidency the following year, elevated the priority of the mission, which was dubbed MEDEA (a nod to the mythical origins of the JASON moniker). MEDEA’s scale grew quickly, as Zall recruited seventy scientists from inside and outside the CIA to analyze satellite images dating back to 1960. In addition to leading the scientific work, she had to navigate the fraught internal politics of federal agencies and advocate for the use of resources that had historically been intended for defense and spycraft rather than environmental research. “I had to fight like a madwoman,” she says. “This could have easily been done in a very sloppy, superficial way, and I wasn’t going to let that happen. I think Cornell put a spirit in me that never left.”
After the Cold War ended, Zall made several trips to Russia, working with the U.S.’s former enemy to broaden the dataset available to science. In 1995, President Bill Clinton signed an executive order releasing more than 800,000 formerly classified spy satellite images, a move informed by the MEDEA project and which led to further scientific discoveries. Ultimately, MEDEA’s data contributed to hundreds of scholarly papers related to environmental change, on such topics as the retreat of the Bering Glacier in Alaska and the deterioration of the West Antarctic Ice Sheet—something that many doubted could ever occur until satellite images proved it was already happening.
Along the way, politics were always a factor: the project was sidelined during the George W. Bush administration, which downplayed the threat of climate change, then reinvigorated under President Barack Obama before finally being disbanded in 2015. (When Mother Jones magazine broke the news, a CIA spokesperson was vague about the reasons.) While MEDEA may have ended, Zall says, it helped to form a scientific consensus that is beginning to drive policy, and she’s heartened to see some people in power taking climate change seriously. “I don’t know if what we did could ever happen again,” Zall says. “But the pendulum is shifting.”