Tuesday, August 13, 2013

The Earth's Spheres

While reading books on meteorology and ecology, I've found references to the 'spheres' of the Earth.  One book mentions four spheres and another book mentions four spheres in one place and five in another.  In one place it's called 'the Earth system', in another 'the climate system', and a third just calls it 'Spaceship Earth'.

Some quotes: "As we study Earth, it becomes apparent that our planet can be viewed as a system with many separate but interacting parts or subsystems.  The hydrosphere, atmosphere, biosphere, and solid Earth and all of their components can be studied separately.  However, the parts are not isolated.  Each is related in some way to the others to produce a complex and continuously interacting whole that we call the Earth system."  - Lutgens and Tarbuck, The Atmosphere, p 4

"...there is a climate system that includes the atmosphere, hydrosphere, solid Earth, biosphere, and cryosphere. (The cryosphere is the ice and snow that exist at Earth's surface.)  The climate system involves the exchanges of energy and moisture that occur among the five spheres." - ibid, p 321

"The biosphere or ecosphere merges imperceptibly (that is, without sharp boundaries) into the lithosphere (the rocks, sediments, mantle, and core of the earth), the hydrosphere (surface and ground water), and the atmosphere, the other major subdivisions of Spaceship Earth." - Eugene Odum, Ecology: A Bridge Between Science and Society, p 31

As I've been reading books on geology, soil science, meteorology, and now, ecology (probably the subject of my next post), I've become more and more aware of how connected they all are.  I tried to get that across in my post on The Chemistry of the World, 8/2/13, where I talked about how plants use minerals from the Earth's crust (the lithosphere) and chemicals from the atmosphere (especially carbon dioxide and nitrogen) as well as water (from the hydrosphere) to grow from, and how we then get those same elements from the plants.  And, as I've talked about in my posts on composting (see for example, Thinking in Circles, 1/6/13), eventually we return those elements back to the earth.

It's interesting thinking about these spheres in terms of climate change as well.  The book on The Atmosphere listed the elements in the atmosphere by percentages and parts per million.  They listed Carbon Dioxide (CO2) as 0.036% or 360 parts per million.  The book has a copyright of 1998.  The news this year is that CO2 in the atmosphere has just reached 400 ppm.  The book also states that "...glacial ice is the Earth's largest reservoir of water outside of the ocean, accounting for 85 percent of the planet's fresh water.  ... As glaciers are composed of solid water, they are usually considered to be part of the hydrosphere.  Sometimes Earth's ice is placed in it's own 'sphere',the cryosphere (cryo is from the Greek for 'icy cold')."  It occurs to me with the rate that the glaciers are melting, that distinction may not be that relevant for long.

It's all only one planet and everything is connected with everything else--and everything changes everything else.  The boundaries between what we call living things and the systems of air, rock, water, and ice aren't as great as we might think.

Quote of the Day:  "The biosphere includes all life on Earth and penetrates those parts of the solid Earth, hydrosphere, and atmosphere in which living organisms can be found.  ...it should be emphasized that organisms do more than just respond to their physical environment.  Indeed, through countless interactions, life-forms help maintain and alter their physical environment. Without life, the makeup and nature of the solid Earth, hydrosphere, and atmosphere would be very different.  ...
"Humans are part of the Earth system, a system in which the living and nonliving components are entwined and interconnected.  Therefore our actions produce changes in all of the other parts." - Frederick Lutgens and Edward Tarbuck

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