Earth System Thinking Class Discussion

The Earth System: Review The Earth system behaves as a single, self-regulating closed system comprising physical, chemical, biological and human components. The fluxes and feedbacks between these components are complex and take place on multiple scales of time and space. The focus of Earth system science is understanding the interactions between the oceans and ice, atmosphere, life, geological processes and the land surface, and how those interactions impact each other and lead to changes on our planet.

Understanding the Earth System Defining the Earth System Understanding the Earth System Energy Flows: Energy from the Sun enters the Earth system, and it is reradiated back into space. Matter Cycles: Matter stays within the system, but can change from one form to another and move between the Earth’s component spheres. Can you describe one example of matter cycling, using the illustration as an example?

II. The Earth System: Flux of Matter and Energy Biosphere: Supplied with a growth medium, plants take root in the soil grow, and exchange gases with the atmosphere. They absorb CO2 from the atmosphere and through the process of photosynthesis they transform solar energy to sugars, and release O2 into the atmosphere. They also breathe in O2 and release CO2 through the process of respiration. Hydrosphere: Water evaporates from the Earth’s surface, and enters the atmosphere. Water vapor cools and condenses in the atmosphere, forming clouds and creating precipitation. Some CO2 gas in the atmosphere disassociates and makes the rainwater weakly acidic: Hydrosphere: Suspended particles are washed into a stream, and during a flood will be deposited on land, along with rich organic nutrients derived from organisms that inhabit the water body, establishing the beginning stages of a soil. Lithosphere: Over time, the acid in rainwater will chemically weather rock, and break it up into smaller particles. Image: Low and Glaser

The Earth System: Energy Flows What energy is powering the fluxes we see on this diagram? Image from GLOBE.gov Carbon, the major building block of life, continuously cycles within and between the spheres. The carbon cycle is one of the most important interconnections within the Earth system.

The Earth System: Energy Flows . Answer: The Sun The Sun is powering the fluxes in carbon that are mediated by life. Stored solar energy powers the fossil fuels creating emissions. Solar energy transformed to chemical energy powers carbon transfer by plants. Stored solar energy in plant cells power the carbon flux taking place by livestock. Image from GLOBE.gov Carbon, the major building block of life, continuously cycles within and between the spheres. The carbon cycle is one of the most important interconnections within the Earth system.

The Earth System: Matter Cycles The layers of soil in a soil profile are called soil horizons. They are created through the interaction of soil formation variables: Climate (hydrosphere and atmosphere) Organisms (biosphere) Parent Material (lithosphere) Topography (lithosphere) Time The interaction of these variables create the landscapes where food is produced: Changes in the Earth system will impact food production. Matter cycles .

Understanding the Earth System Earth Systems: Scales of Analysis Understanding the Earth System As a scientist, you identify the boundaries of the system you are studying. Earth systems can be analyzed at many spatial scales. Biosphere atmosphere Spatial scales of analysis change propagates In all directions hydrosphere lithosphere

Example of a regional scale analysis Human impact- agriculture impacts forest ecosystem (biosphere) Agricultural growth, Paraguay The Gran Chaco is a vast plain of some 850,000 square kilometers (328,000 square miles) which spans parts of Argentina, Bolivia, Paraguay and Brazil. It is an important and fragile ecosystem. In Paraguay, the Chaco covers 61 percent of the nation’s territory but holds just 3 percent of its population. Sixty percent of Paraguay’s Chaco is grassland, used for extensive cattle production. Some 357 square kilometers (138 square miles) is used to grow crops. Comparing the satellite images from 1977 and 2008, the change in land use is evident, mainly due to livestock production and agriculture, with a considerable increase in parcel agriculture (geometric patterns) in the 2008 image. Images: NASA Images of Change. 1977 2008

II. The Earth System: Flux of Matter and Energy Matter Cycles at Regional Spatial Scales How is the Global Food System connected to the Earth system? Biosphere atmosphere change propagates In all directions hydrosphere lithosphere Food System Diagram Source: Hunt041 Creative Commons Attribution-Share Alike 3.0 Unported license.