Stable Isotope Laboratory


The INSTAAR Stable Isotope Lab is a focal point of interdisciplinary research programs: we partner with a global array of researchers from a variety of academic institutions and governmental agencies. Isotopes provide a unique tool because they indicate, record, integrate, and trace processes in the global environment.

Our research includes

Carbon Cycle and Greenhouse Gases

Rachel Edie changes gas flasks out on Spock, a mass spectrometer that measures stable isotopes of carbon and oxygen in atmospheric CO2, primarily from the NOAA CMDL Cooperative Air Sampling Network. Photo by Ethan Welty.

We measure the stable isotopes of carbon dioxide and methane in order to understand global sources and sinks of these greenhouse gases.

As the concentrations of greenhouse gases increase, the Earth's climate is changing. Two of the most important heat-trapping gases are carbon dioxide and methane, yet we don't fully understand their sources - where and how these gases are released - and their sinks - how they are taken up or destroyed.  Stable isotopes are very useful for understanding sources and sinks due to processes that discriminate against one isotope over the other. For instance, because plants strongly discriminate against the heavy isotope of CO2, we can use d13CO2 to estimate ocean versus land uptake of carbon dioxide. Because sources of methane have different isotopic signatures, we can use d13CH4 to calculate emissions of methane from differerent sources. The isotope measurements, along with concentrations of greenhouse gases in our atmosphere, constrain models of these gases, and increase their predictive capability for understanding future climate regimes and making policy decisions.

The INSTAAR Stable Isotope Lab (SIL) has collaborated with the Carbon Cycle Greenhouse Gases Group (CCGG) at NOAA Environmental Research Laboratory Global Monitoring Division to measure C13 and O18 of carbon dioxide since 1990, and C13 of methane since 1998. This involves measuring flasks and programmable flask packages from the NOAA Cooperative Sampling Network. We are currently working on our system for analysis of deuterium of methane, are developing a method for analyzing C13 and O18 of carbon monoxide as part of the INFLUX project, and have completed a pilot project studying atmosperic N2O isotopes and isotopomers.

See NOAA ESRL for more information, go directly to the data, and learn more about why isotopes are useful for understanding sources and sinks of carbon.

Ice Cores

Video tour by grad student Tyler Jones of work and life at the North Greenland Eemian Ice Drilling (NEEM) station atop the Greenland ice sheet. The international NEEM team retrieved an ice core from the top of the ice sheet down to bedrock, containing climate records reaching back 115,000 years.

We measure the stable isotopes of oxygen and hydrogen in water from Ice cores. On Earth's great ice sheets, Greenland and Antarctica, snow accumulates and never melts, creating a repoitory of precipitation back in time. Stable isotopes of precipitation are a proxy for temperature when the snow fell, making ice cores a rich paleoclimate archives. In addition, ice cores preserve records of atmospheric gases, chemistry, and physical properties, and they are unique for their combination of high resolution and long time scales.  Understanding the climates of the past is essential for predicting the Earth’s responses of human-caused climate change, and ice cores are invaluable in this effort.

For more than 15 years, SIL has been involved in ice core projects in Greenland, Antarctica, the high-altitude tropics (Ecuador, Peru, Tibet), and other regions. Over this time, SIL has become a world leader in measurement of both deuterium/hydrogen and oxygen-18/16 ratios of ice. In addition to the stable isotope analysis, we are involved with the coring, processing, and modeling/analysis of the data.

We have recently completed ice core projects at NEEM, Greenland, and WAIS Divide, Antarctica. We measured the ice from WAIS Divide on a custom-built continuous melter system connected to a Picarro cavity ring-down mass spectrometer, resulting in higher-than ever measurement resolution on a deep core. We will use this system to measure the core from South Pole, and will develop the next generation core for analysis of the Renland Ice Core.

Natural gas development impacts and best practices

The Mobile Methane Analyzer. Photo by Christi Turner.

SIL is participating in the CU-based, NSF funded Sustainability Research Network called the Air Water Gas project which is aimed at studying the oil and gas industry in the Rocky Mountain West (

The mission of this project is to provide a logical, science-based framework for evaluating the environmental, economic, and social trade-offs between development of natural gas and protection of water and air resources. The project also aims to educate the public and influence the development of policies and regulations governing natural gas and oil development.

Unlike all of our lab-based measurements, Mobile Methane measurements are recorded on the fly as the vehicle drives. The data is plotted onto an interactive map and Landsat image.

Visual display of a mobile methane sampling along roads in Weld County.

And more...

Stable Isotopes in the Biosphere

Carbon isotope ratios of organic material are useful tools in ecology and ecosystem science. We have measured thousands of leaf, soil, and other organic materials in studies aimed at understanding plant physiology, hydrology, and biogeochemistry.


Stable Isotopes in Precipitation

The hydrologic cycle plays in important role in ice core research. Many of the discoveries made from polar ice cores have deepened our understanding of long term climate signals in both temperature and precipitation; likewise, understanding isotopes in precipitation today are essential to understanding the ice core record. Stable Isotopes are a unique tracer that can reveal volumes about the origin and distribution of precipitation on our planet.

The SIL has collaborated in a large scale effort of analyze the stable isotopes of archived samples obtained from the Global Network of Isotopes in Precipitation (GNIP) program. Students at CU have produced and analyzed seasonal patterns of isotopes in precipitation over the United States.


Contact Information

(Phone) 303 492-7985
1560 30th Street
Boulder, CO 80303