Earth does not have infinite resources. When human consumption increases it places stress on the natural processes that renew resources and depletes those which cannot be replaced.
Solar energy (energy from the sun; the primary source of energy on the Earth) drives global atmospheric and oceanic circulation, which joins with surface features, latitude and other factors to determine weather (this happens in the troposphere layer of the atmosphere) and climate (the sum of all weather events occurring over many years). One of those factors is the effect of composition of the atmosphere and on the amount and type of solar energy that reaches the Earth surface. In particular, stratospheric ozone absorbs ultraviolet radiation (harmful radiation causes cancer), reducing the amount that reaches the surface. Also, carbon dioxide and other greenhouse gases absorb and re-emit infrared radiation (heat; note: not the same as ultraviolet radiation) resulting in an increase in surface temperature.
Wind and ocean currents are produce by the differential heating of the Earth’s surface and atmosphere. Winds are caused by convention (rising of warm air and the sinking of cold air) with the pattern of air circulation caused by the unequal heating of the Earth’s surface (both land and water). During the day the land heats up much faster than the ocean (because there is less land than water to heat up) and it causes a sea breeze (where the wind/breeze comes from the sea); during the night the ocean is still heated from the day and the land cools and it causes a land breeze (where the wind/breeze comes from the land). Ocean currents are caused by tides, earth wind systems, and difference in density. Surface currents are influenced by the wind and it helps move heat energy across the earth. Deep water currents are caused by the differences in water’s density. Cold, salty water is denser (heavier) than warmer water with less salt. The movement of the water to go to it’s “comfortable” density is what cause the water currents.
Scientific evidence suggests that the Earth, along with the solar system formed approximately 4.5 billion years ago when a cloud of matter condensed into the planets and the sun. Originally a ball of molten matter, the Earth has cooled and differentiated into layers (core, mantle, crust, hydrosphere, atmosphere). The crust (the continents and ocean floors) consists of large plates that slowly move on the more fluid mantle. The motions of the plates cause earthquakes, volcanoes, mountain building, and sea floor spreading. Rocks and fossils, which may be dated by noting their positions (and location), studying the composition of the rock (what the rock is made of), or using radioactive dating (many rocks contain radioactive elements that decay at a constant rate – it is not affected by outside factors such as changes in temperature, pressure or chemical state), give us evidence about the changing characteristics of the Earth over time.
Principle of Uniform Processes: states that the processes that are observed acting on earth today also acted on it in the past. “The present is the key to the past”
Principle of Superposition: states that the bottom layer in a group of rock layers is usually the oldest and the top layer is the youngest.
When photosynthetic organisms (organisms that can changing carbon dioxide into oxygen) appeared on earth, they dramatically altered the atmosphere by lowering the amount of carbon dioxide and adding oxygen. Sudden, widespread changes in the atmosphere may be caused by large events such as volcanic eruptions or the impact of meteors or comets (which increase the levels of carbon dioxide). These changes may affect world-wide climate for years.
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