Annmarie Eldering, PhD

Environmental Engineering, CalTech, Project Scientist, NASA’s Orbiting Carbon Observatory -3.

Category of Humanitarian Benefit: Environmental Improvement

Short Biography/Background

Dr. Annmarie Eldering is the Project Scientist of NASA’s Orbiting Carbon Observatory -3 (OCO-3) and Deputy Project Scientist of its predecessor mission, OCO-2. In these roles, she conducts pioneering science investigations and leads the development of scientific applications for these groundbreaking missions.

Dr. Eldering received her Masters and PhD degrees in Environmental Engineering Science from the California Institute of Technology. After holding faculty positions at the University of Iowa and University of California Los Angeles, she joined the Jet Propulsion Laboratory in 1999. While working at JPL, she has additionally held a position as an Adjunct Assistant Professor and Bjerknes Fellow in the UCLA Atmospheric Sciences Department.

During her time at JPL, Dr. Eldering has worked on a variety of spaceborne atmospheric investigations, and quickly rose to the position of Section Manager of the Atmospheric Sciences section. As Section Manager, she led a team of over 60 scientists devoted to various aspects of atmospheric dynamics and composition. She has worked on new mission concept studies for future atmospheric composition measurements, developed techniques for remote sensing of aerosols with high spectral resolution data, and created a new UCLA upper-level undergraduate course on ‘Air and Water Pollution’ among other activities. Dr. Eldering has over 90 well-cited peer reviewed publications and is an excellent, sought-after mentor. She has mentored students at U. Iowa, UCLA, and early career scientists at JPL.

Project Name and Description

From their vantage point, the Orbiting Carbon Observatory -3 (OCO-3) and its predecessor, OCO-2, watch the Earth breathe from space. OCO-2 was launched July 2, 2014 and revisits areas on Earth at roughly the same time of day due to its sun-synchronous orbit. OCO-3 was launched May 4, 2019 and docked on the International Space Station two days later. It views the lower latitudes several times a day at varying times of day. OCO-2 and OCO-3 accurately and precisely measure carbon dioxide levels in the atmosphere to a few parts per million. 

The targeted measurements taken from OCO-2 and OCO-3 enable the science community to disentangle which sources of carbon dioxide are in nature and which are anthropogenic. More specifically, these missions collect the space-based measurements needed to quantify variations in carbon dioxide (CO2) with the precision needed to improve our understanding of CO2 fluxes on regional scales (≥1000km) and the processes controlling their variability over the seasonal cycle.

Global maps of CO2 derived from these data reveal some of the most robust features of the atmospheric carbon cycle. These include CO2 enhancements co-located with intense fossil fuel emissions in eastern US and eastern China, which are most obvious between October and December. Enhanced CO2 coincident with biomass burning in the Amazon, central Africa, and Indonesia is also evident in this season. In May and June, when the north–south CO2 gradient is largest, these sources are less apparent in global maps. During this part of the year, OCO-2 maps show a more than 10 ppm reduction in CO2 across the Northern Hemisphere, as photosynthesis by the land biosphere rapidly absorbs CO2.

As the carbon cycle science community continues to analyze the data, information on regional-scale sources (emitters) and sinks (absorbers) which impart CO2 changes on the order of 1 ppm, as well as far more subtle features, emerge from this high-resolution global dataset. Since the beginning of the OCO-2 mission, tropical forests, once thought to be a significant CO2 absorber, show strong, persistent positive CO2 anomalies, suggesting that they are now emitters. Efforts are ongoing to determine whether these and other features of the space-based datasets indicate biases in the space-based CO2 estimates, misinterpretations of the ground-based measurements due to limitations in their resolution or coverage, or evidence for evolution of the carbon cycle in response to climate change.

Dr. Eldering led the team of scientists who made these discoveries. In addition, she has made a key contribution consisting of prioritizing science requirements within a cost capped development budget while being able to meet the overall mission objectives.  Dr. Eldering’s scientific leadership and effective communication skill have been invaluable to the success of the mission and scientific achievement. 




Carbon dioxide (CO2) is the main greenhouse gas produced by human activities and the primary driver of climate change. The NASA Orbiting Carbon Observatories 2 and 3 are the first NASA sensors designed to measure CO2 with the precision, accuracy, resolution and coverage needed to identify the sources emitting it into the atmosphere and the natural processes that absorb it at the surface. These and other space-based greenhouse gas sensors are providing critical information to policy makers looking for ways to reduce greenhouse gas emissions. Dr. Eldering has played a critical role in the implementation of these pioneering systems and is developing a new measurement system that will provide more frequent coverage and retrieve other greenhouse gases contributing to climate change.