Fundamental Questions

Despite the Critical Zone's importance to terrestrial life and many environmental issues, it remains poorly understood. Key questions include:

• How does the Critical Zone form?
• How does it operate?
• How does it evolve?

There are many followup questions as well. For example:

• How will the Critical Zone respond to projected climate and land use changes?

Specific Questions

Each Critical Zone Observatory is helping work on these fundamental questions along with numerous others. Some questions are specific to the unique characteristics of their field site and the talents of their collaborative research team. Some examples:

• What is the legacy of climate and geologic history in critical zone architecture?
   - Boulder
• How does variability in energy input and related mass flux influence critical zone structure and function?
    - Jemez-Catalina
• How does saprolite advance vary with regolith thickness and landscape position?
   - Luquillo
• How does water sculpt a landscape on shale bedrock?
   - Shale Hills
• How does landscape variability control how soil moisture, evapotranspiration and streamflow respond to snowmelt and rainfall?
   - Southern Sierra

Cross-CZO Questions

A key advantage of the coordinated system of Critical Zone Observatories is that it can address the biggest questions by leveraging differing environments and histories.  More specifically, cross-CZO science can begin to answer questions such as:

• How do processes that nourish ecosystems change over human and geologic time scales?
• How do biogeochemical processes govern long-term sustainability of water and soil resources?
• What processes control fluxes of carbon, particulates, and reactive gases over different timescales?
• How do variations in and perturbations to chemical and physical weathering processes impact the Critical Zone?

An expressed goal of the CZO program is to catalyze transformative Earth surface science in the coming decade by developing cross-site science that helps to establish: 1) a unifying theory of CZ evolution; 2) coupled systems models to explore how CZ services respond to anthropogenic, climatic, and tectonic forcing; and 3) data sets that document differing CZ geologic and climatic settings, inform the theoretical framework, constrain conceptual and coupled systems models, and test model-generated hypotheses.

Cross-CZO studies >

Our Approach

Answering fundamental questions requires much better knowledge of 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 non-linear and can range across vast scales - from atomic to global, and from seconds to eons.

Interdisciplinary & Multidisciplinary

To better understand how the complex processes of the Critical Zone are linked, the U.S. NSF National CZO Program employs a systems approach across a broad array of sciences. This interdisciplinary and multidisciplinary approach integrates many disciplines, especially in the geological and biological sciences. Examples include hydrology, ecology, biogeochemistry, and geomorphology.

Multiple Disciplines >

A Common Infrastructure

Our systems approach across disciplines is well supported via our infrastructure. Our nine observatories span a range of climatic, geologic, and physiographic environments, from California to Puerto Rico. Each CZO is working toward a common set of resources, which will enable comparison of whole-watershed energy and mass balances across a variety of settings.

Infrastructure >

 

Community & Collaboration

Within each CZO, scientific collaborations are common, often bringing together researchers from different institutions and crossing disciplinary boundaries.  This team-based approach helps foster a strong community, which is further strengthed by graduate student involvement.  Similar collaborations occur between investigators and students at different CZOs as well as with members of other US science programs.  Moreover, the US CZO program also works with an international network of Critical Zone investigators and research sites.

Partner Organizations >

Predictive Ability

An immediate challenge is to develop a robust predictive ability for how the structure and function of the Critical Zone evolves, including 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 interactions between the varied climatic and geologic factors that distinguish different regions.
• 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. 

Read: Future Directions for CZO Science >

Models >