Critical Zone Observatories

June 16, 2011, 12:52 pm
Source: National Science Foundation
Content Cover Image

Source: National Science Foundation.

The Critical Zone:
Where Rock Meets Life

The Critical Zone Observatories constitute a national research program supported by the National Science Foundation.

The Critical Zone is Earth’s porous near-surface layer, from the tops of the trees down to the deepest groundwater. It is a living, breathing, constantly evolving boundary layer where rock, soil, water, air, and living organisms interact. These complex interactions regulate the natural habitat and determine the availability of life-sustaining resources, including our food production and water quality.

Despite the Critical Zone's importance to terrestrial life, it remains poorly understood:

  • How does the Critical Zone form?
  • How does it function?
  • How will it change in the future?

More specifically, too little is known about how physical, chemical, and biological processes in the Critical Zone are coupled and at what spatial and temporal scales. Many of these processes are highly nonlinear and can range across scales from atomic to global, and from seconds to aeons.

Understanding the complex web of physical, chemical, and biological processes of the Critical Zone requires a systems approach across a broad array of sciences: hydrology, geology, soil science, biology, ecology, geochemistry, geomorphology, and more.

For more information about the importance of an interdisciplinary approach, read "Frontiers in Exploration of the Critical Zone: Report of a workshop sponsored by the National Science Foundation (NSF). 2005" Download PDF

Main Question

How will the Critical Zone evolve in response to changing climate & land use?

The immediate challenge is to develop a robust predictive ability for how the structure and function of the Critical Zone evolves and how it will respond to projected climate and land-use changes.

This predictive ability must be founded on:

  • Broad knowledge of the complex physical, chemical, and biological processes of the Critical Zone.
  • The ability to describe how the varied climatic and geologic factors that distinguish different regions interact.
  • Advances in theory, modeling, and measurement.

Over the next decade, the CZO program will produce a fundamental understanding and four-dimensional data sets that will stimulate, inspire, and test the resulting predictive models.

Main Goals


CZO is working toward a holistic conceptual model of critical-zone evolution that integrates new knowledge of coupled hydrological, geochemical, geomorphic, and biological processes. We are including both positive and negative feedbacks and their distribution in time and space.

2. DEVELOP COUPLED SYSTEMS MODELS to explore how critical zone services respond to anthropogenic, climatic, and tectonic forcings.

CZO is building systems models that quantitatively combine multiple processes, often spanning a whole watershed. These models typically track fluxes and storage of energy, water, carbon, sediments, and/or other materials.

3. DEVELOP AN INTEGRATED DATA/MEASUREMENT FRAMEWORK sufficient for documenting a range of geologic and climatic settings, informing our theoretical framework, constraining models, and testing model-generated hypotheses across a CZO Network.

CZO is assembling the needed infrastructure for an integrated data/measurement framework For more details on this integrated framework and a common infrastructure, see our Data page and Sites (Infrastructure) page.

For more information on all three goals
Read "Future Directions for Critical Zone Observatory (CZO) Science" (PDF)>>

Initial Results

We are making progress on all three main goals. Results of our interdisciplinary efforts are beginning to emerge, as shown in our publication highlights and news, as well as on the individual CZO websites.

Research at the individual CZOs:
Boulder Creek| Christina River | Jemez - Catalina | Luquillo | S. Sierra | Shale Hills

News at the individual CZOs:
Boulder Creek| Christina River | Jemez - Catalina | Luquillo | S. Sierra | Shale Hills

We will also feature more results on the web as we bring our new integrated website system online.




(2011). Critical Zone Observatories. Retrieved from


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