M1 L2: Earth Systems

• Earth is a complex system of interacting physical, chemical, and biological processes, and provides a natural laboratory whose experiments have been running since the beginning of time.
• A system is a group of interacting or interrelated entities that form a unified whole. The interaction of the different compartments of the earth that facilitate the continuous movement of water on, above, and below the surface of the earth is an example of a system.
• Different Types of System

  1. Isolated system
  2. Closed system
  3. Open system
• Isolated system - is a system that cannot exchange either energy or matter with its surrounding environment
• Closed system - a system that allows only the exchange of energy with its surroundings
• Open System - An open system is a system that has external interactions. It allows the exchange of matter and energy.
• The Earth system as a whole is a closed system. The boundary of the earth system is the outer edge of the atmosphere. Virtually no mass is exchanged between the Earth system and the rest of the universe.
• The closed Earth system is comprised of different open systems, the atmosphere, biosphere, hydrosphere, and geosphere. The arrows indicate flows between the systems. For instance, the atmosphere and biosphere continually exchange energy (e.g. heat) and mass (e.g. water vapor, carbon dioxide, oxygen) across their system boundaries. Earth is a dynamic body with many separate, but highly interacting parts or spheres.
• The Earth's Four Spheres

  • Lithosphere
  • Atmosphere
  • Hydrosphere
  • Biosphere
• Lithosphere - comprises the solid Earth and includes both Earth’s surface and the various layers of the Earth’s interior.
• Atmosphere - a gaseous envelope that surrounds the earth and constitutes the transition between its components and the vacuum of space
• Hydrosphere - includes all water on Earth (including surface water and groundwater)
• Biosphere - the life zone of the Earth and includes all living organisms and all organic matter that has not yet decomposed.
• The Atmosphere

  • The Earth is surrounded by a blanket of air, which we call the atmosphere. The atmosphere consists of unique layers (the troposphere, the stratosphere, the mesosphere, and the thermosphere). The exosphere is the outermost region.
  • One of the most important processes by which the heat on the Earth's surface is redistributed is through atmospheric circulation.
• The Atmosphere

  • The atmosphere reaches over 560 kilometers (348 miles) up from the surface of the Earth. The atmosphere is primarily composed of nitrogen (about 78%) and oxygen (about 21%). Other components exist in small quantities.
• Atmosphere - Interactions with other Earth System components

  • Hydrosphere - The gases of the atmosphere readily exchange with those dissolved in water bodies (e.g. oceans, lakes, etc.)
  • Biosphere - The atmosphere supplies oxygen and carbon dioxide that form the basis of life processes (photosynthesis and respiration).
  • Lithosphere - Gases in the atmosphere react with water to produce weak acids that aid in the breakdown of rock.
• • Exosphere
  • Themosphere
  • Mesopause
  • Mesosphere
  • Stratosphere
  • Ozone Layer
  • Troposphere

  A) 1

  B) 2

  C) 3

  D) 4

  E) 5

  F) 6

  G) 7

  
• The biosphere is the “life zone” of the Earth and includes all living organisms (including humans), and all organic matter that has not yet decomposed. The biosphere is structured into a hierarchy known as the food chain (all life is dependent on the first tier – mainly the primary producers that are capable of photosynthesis). Energy and mass are transferred from one level of the food chain to the next.
• The Biosphere

  • It covers all ecosystems—from the soil to the rainforest, from mangroves to coral reefs, and from the plankton-rich ocean surface to the deep sea.
  • For the majority of life on Earth, the base of the food chain comprises photosynthetic organisms. During photosynthesis, CO2 is sequestered from the atmosphere, while oxygen is released as a byproduct. The biosphere is a CO2 sink, and therefore, an important part of the carbon cycle.
• Biosphere - Interactions with other Earth System components

  • Atmosphere - Life processes involve many chemical reactions that either extract or emit gases to and from the atmosphere (e.g. photosynthesis consumes carbon dioxide and releases oxygen, whereas respiration does the opposite).
  • Hydrosphere - Evaporation of water from leaf surfaces (transpiration) transfers water to the atmosphere.
• Biosphere - Interactions with other Earth System components

  • Lithosphere - The biosphere is connected to the lithosphere through soils (mixtures of air, mineral matter, organic matter, and water). Plant activity (e.g. root growth and organic acid production) are also for the mechanical and chemical breakdown of the rocks.
• The hydrosphere contains all the water found on our planet. Water found on the surface of our planet includes the ocean as well as water from lakes and rivers, streams, and creeks. Water found under the surface of our planet includes water trapped in the soil and groundwater. Water found in our atmosphere includes water vapor. Frozen water on our planet includes ice caps and glaciers. Only about 3% of the water on Earth is freshwater, and about 70% of the freshwater is frozen in the form of glacial ice.
• The Hydrosphere

  • The oceans are important sinks for CO2 through direct exchange with the atmosphere and indirectly through the weathering of rocks.
  • Heat is absorbed and redistributed on the surface of the Earth through ocean circulation.
  • Through the process of weathering and erosion, the hydrologic cycle is another important process contributing to the shaping and reshaping of the surface of the Earth. This is an important link among the hydrosphere, atmosphere, and lithosphere that the learners should be able to identify themselves.
• Hydrosphere - Interactions with other Earth System components

  • Atmosphere - Water is transferred between the hydrosphere and biosphere by evaporation and precipitation. Energy is also exchanged in this process.
  • Biosphere - Water is necessary for the transport of nutrients and waste products in organisms.
  • Lithosphere - Water is the primary agent for the chemical and mechanical breakdown of rock (weathering), to form loose rock fragments and soil, and sculpt the surface of the Earth.
• The lithosphere is the solid Earth that includes the continental and oceanic crust as well the various layers of Earth’s interior. 94% of the Earth is composed of the elements oxygen, silicon, and magnesium. The geosphere is not static, and its surface (crust) is in a constant state of motion. Mineral resources are mined from the geosphere.
• The Lithosphere

  • In many places, the lithosphere develops a layer of soil in which nutrients become available to living organisms, and which thus provides an important ecological habitat and the basis of many forms of life.
  • The surface of the lithosphere is subject to processes of erosion, weathering, and transport, as well as to tectonic forces and volcanic activity, which result in the formation of landforms.
• Lithosphere - Interactions with other Earth System components

  • Atmosphere - volcanism spews significant amounts of gases into the atmosphere. For example, volcanoes inject large amounts of sulfur dioxide into the upper atmosphere, resulting in global cooling due to the SO2 that is converted to sulfuric acid aerosols that block incoming solar radiation. The blocked solar radiation can cause global cooling
• Lithosphere - Interactions with other Earth System components

  • Hydrosphere - The formation of many minerals involves the incorporation or release of water. Also, water speeds up chemical reactions that produce or destroy minerals, and aids in the melting of rock.
  • Biosphere - Nutrients released from rocks during their breakdown are dissolved in water (to be used by aquatic plants).