Science Story May 2022

Dr. Kate Maher at Kettle Ponds

Carbon knowledge

You don’t have to be a scientist to know that carbon is the key to life. Everything on Earth is fundamentally made from carbon, and since our planet itself is a self-contained environment, the amount of carbon stays the same. It simply moves around, cycling from the Earth to the atmosphere and back again. The problem occurs when there’s an imbalance. Right now, there’s too much of it in the atmosphere in the form of carbon dioxide (CO2), more than there has been in 800,000 years. And because CO2 absorbs heat, it’s a major player in climate change.

The more we understand the carbon cycle — where it’s stored on Earth, how it moves into the atmosphere, and what drives the whole process — the better we can predict what the future holds for our planet and how to prepare for it.

One scientist who is deeply enmeshed in the carbon cycle is Dr. Kate Maher of Stanford University. She was introduced to RMBL through the Lawrence Berkeley National Laboratory. In 2015, the Department of Energy was encouraging researchers to look into the intersection between climate change and carbon cycling with the goal of improving models to help science understand the global connections between climate change and ecosystems. Dr. Maher came to scout sites at RMBL to see whether they would work for her research.

Like so many scientists before her, she fell in love with the area and not just for its natural beauty. She was fascinated by the geological diversity of RMBL’s setting within the unique East River watershed. The variety of rock and soil, the volcanic and glacial history, the types of river forms, the different morphologies of the valley, and the wide variety of vegetation, with its transitions from conifers to aspens to meadows: these are complexities not usually found at most field stations.

So Dr. Maher and her team started investigating how much carbon dioxide was coming out of the soils as plants transition from snowmelt season to growing season to dormancy. The researchers wanted to understand how microorganisms in the soil respond to these seasonal cycles and what role they play in emitting CO2 back to the atmosphere. Ultimately, scientists want to find out how plants are responding to a changing climate and how these responses are linked to changes in the soils and microorganisms and, consequently, how these processes are driving changes in the soil’s carbon storage.

The point is to understand enough about the carbon cycle to build better models that will instill more confidence in future predictions. Reliable models can be critical guides to help water and land managers create strategies to deal with a changing climate. What’s more, accurate models are useful for informing climate solutions on a global scale.

It’s no small task to model and predict the amount of carbon in the soil, how it’s generated, and how it releases CO2 into the atmosphere. But within the last few years, Dr. Maher, in partnership with the US Geological Survey, has been able to upgrade the team’s sensing technology, yielding much more data with much less effort. In early 2015, the team installed thin metal tubes to manually collect the gas in the soil, from which they can tell the amount of carbon in the soil and roughly how it was formed. Now these tubes have been replaced with special sensors that routinely detect how much CO2 is in the soil and then send the data back to Gothic.

The researchers also measure soil temperature and moisture and observe how the plants change over time using satellite images and airborne imagery of the topography and vegetation. The satellite measures the reflection of light from the vegetation through a range of spectra, and this data tells researchers such things as how green the vegetation is, how much it’s photosynthesizing, and the stage of its growth. Moreover, with sophisticated sensors, solar panels, and radio transmission, the scientists can get the data in close to real time, measuring 24 hours a day, 12 months of the year. Researchers are even starting to look into methods for capturing CO2 in soils using what they’re learning at RMBL.

“We’re finally becoming a data-rich field,” Dr. Maher said. “We’re able to measure things in a lot of places with a lot more resolution that we could before. It’s a new and exciting frontier, and RMBL is at the forefront.”


Kate Maher, PhD, is a professor of Earth System Science at Stanford University and faculty director for the interdisciplinary program in Design at the Hasso Plattner Institute of Design. Kate’s degrees include Civil and Environmental Engineering (MS) and Earth and Planetary Sciences (PhD) from UC Berkeley. Her research focuses on the application of models to investigate a diverse array of questions including the evolution of Earth’s subsurface environments and their links to the carbon cycle, subsurface storage of CO2, and ground water contamination. By combining computer models with field and laboratory measurements, her research links the movement of water to geochemical reactions and biological processes to understand our unique planet. Kate is a fellow of the American Geophysical Union and was awarded the James B. Macelwane Medal. She is also a senior fellow at the Woods Institute for the Environment.