Sources of Climate Change

Since many sources claiming to distribute accurate information regarding climate change tend to have some sort of their own political agenda, I will concentrate mostly on the discussion of climate change presented by the textbook, The Cosmic Perspective: The Solar System.  Earth’s climate has been relatively stable throughout its history when compared to Mars, for example, which has lost the majority of its once liquid water-friendly atmosphere.  The greatest swings in the climate of our planet, at least since our atmosphere has developed oxygen levels sufficient to sustain terrestrial life, have been ice ages.  The Earth cools down for a while, then heats back up through the carbon dioxide cycle.

The Carbon Dioxide Cycle

The Carbon Dioxide Cycle

The most basic explanation of the CO2 cycle, as seen above, is that CO2 is released into the atmosphere by outgassing.  Some of this atmospheric carbon dioxide dissolves in rainwater, leading to acid rain, which erodes the Earth’s rocky surface and increases the amount of carbon in Earth’s water.  This carbon then reacts with calcium to form carbonate rocks, which are eventually sucked down into Earth’s mantle through plate tectonics, where they heat up and are eventually outgassed through volcanoes, continuing the cycle.

This cycle acts as a natural equalizer for Earth’s temperature because if the Earth heats up due to excess CO2 in the atmosphere, water will evaporate more easily, leading to more precipitation, which dissolves CO2 from the atmosphere, leading to less of a greenhouse effect.  Likewise, if the Earth cools down, there will be less precipitation and less CO2 dissolved from the atmosphere, increasing CO2 levels, leading to more of a greenhouse effect.

Though many other factors can cause long-term climate change, such as solar brightening, changes in Earth’s axial tilt, and changes in Earth’s reflectivity, when climate change becomes more complex and the human political agenda can come into play is when we discuss the effects of human activity on climate change and greenhouse gas levels.  As humans increase our consumption of fossil fuels, excess greenhouse gases are released into the atmosphere, throwing off the CO2 cycle.  This spike in greenhouse gases slows the escape of IR light from the atmosphere, leading to an increase in atmospheric heating.  This heating leads to more precipitation and the melting of polar ice, increasing sea levels and reducing Earth’s reflectivity, which leads to more absorption of the Sun’s visible light, more IR light being emitted by Earth, and more warming.  It is necessary for humans to reduce greenhouse gas emissions in order to allow the CO2 cycle to naturally guide Earth’s climate.


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