2009 Science, Technology and Environment

Compton J. Tucker

Pioneered satellite-based monitoring of vegetation to track human-induced climate change, provide early warning of famine, and prevent deforestation and the spread of tropical disease.

Compton J. Tucker, a scientist at NASA’s Goddard Space Flight Center, has given new meaning to the old idiom—seeing the forest for the trees.

He helped create a satellite-based system to track the biological activity of plant life at the local, regional, continental and, subsequently, global level. As a result, scientists can now measure changes in individual vegetation in an aggregate, providing a living picture of entire ecosystems whose practical applications range from a warning system for disease outbreaks to a method for tracking emissions that might contribute to climate change.

“His work, in many respects, has been as influential as the image of the Earth seen from the moon. It allowed us to see, for the first time, how the Earth’s vegetation reflects the seasonal pulse of the planet. Nobody else can claim these achievements,” said Dr. Darrel Williams who is Tucker’s supervisor and associate chief of Goddard.

Before Dr. Tucker’s breakthrough, vegetation was simply classified and tracked according to the type of plant life found in any particular area. Dr. Tucker helped create the Normalized Difference Vegetation Index (NDVI), which uses a remote sensing system to monitor the photosynthetic activity of plants and trees, offering an ever-changing picture of ecosystems.

By enabling researchers to see when changes are taking place in the land biosphere, this system has been used to measure agricultural productivity, develop early warning systems for famines, measure the growth of vegetation and identify regions at risk from diseases linked to climate.

More specifically, satellite NDVI data are a key component of USAID’s Famine Early Warning System, which is used to monitor agricultural productivity and prevent famine. NDVI was used to predict a major Rift Valley fever outbreak in East Africa, enabling preventative measures to be taken four weeks before the disease appeared. The United Nations has used satellite data to predict insect infestations in Africa, Arabia and Southwest Asia, providing early warnings that have minimized the destruction of agricultural crops.

Tucker’s measurements are also having a tremendous impact on helping scientists measure how much, or how little, carbon dioxide is being consumed, and the effect this is having on climate change.

“Understanding the consumption of carbon dioxide by plants has a global impact because it can provide data on the potential damage of global warming,” said Robert Dickinson a professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology.

In the beginning, Tucker said other scientists didn’t believe in what he was doing, but he did not let this negativity get in the way. “I was interested in experimentation and was not nervous about changing techniques that didn’t work,” said Tucker.

Earth scientists credit Tucker’s work with the NDVI in establishing a worldwide standard to measure not just how many plants and trees are out there, but how well they are performing. “His genius is in his ability to take data that was qualitative and make it quantitative,” Dickinson said.

“Dr. Tucker tirelessly maintained the data for nearly 30 years. Every model of our ecosystem starts with Dr. Tucker’s NDVI,” said Inez Fung, professor and co-director of the Berkeley Institute of the Environment at the University of California, Berkeley.

His 1985 breakthrough article in “Science” magazine transformed the field of ecology by detailing how the NDVI could be used to examine the vegetative state of the entire continent of Africa. A digitally processed image showing the results was like nothing seen before and made NDVI the cornerstone of global vegetation monitoring.

Tucker’s work has been widely published and referenced.  He is the author of more than 155 scientific papers that have been cited more than 12,000 times by other researchers. The scientific community has created something called the H-index to measure how often a particular author’s work has been cited by others. A score of 20 to 30 on the H-index is considered good—Tucker’s is 55.

Tucker’s admiration and respect extends beyond his scientific peers. In addition to his work at NASA, Tucker’s lectures at the University of Maryland, Baltimore and elsewhere are popular with students and faculty alike. “He is known around campus for being very kind and modest, yet funny,” said Fung. “Everyone loves him. He’s got the twinkle in his eye.”