How Do Humans Contribute to Global Climate Change?

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Growing trees capture carbon dioxide, reducing greenhouse gases. Walter Hodges/Photographer's Choice/Getty

Throughout most of human history, and certainly before human beings emerged as a dominant species throughout the world, all climate changes were the direct result of natural forces like solar cycles and volcanic eruptions. Along with the Industrial Revolution and an increasing population size, humans began altering climates with ever growing influence, and eventually surpassed natural causes in their ability to change climate.

Human-caused global climate change is primarily due to the release, through our activities, of greenhouse gases.

Greenhouse gases are released into the air, where they persist for a long period at high altitude and absorb reflected sunlight. They then warm the atmosphere, the surface of the land, and the oceans. Many of our activities contribute greenhouse gases to the atmosphere.

Fossil Fuels Carry Much of the Blame

The process of burning fossil fuels releases various pollutants, as well as an important greenhouse gas, carbon dioxide. We know that the use of gasoline and diesel to power vehicles is a large contributor, but overall transportation only accounts for approximately 14% of total greenhouse gas emissions. The single largest culprit is electricity production by coal, gas, or oil-burning power plants, with 20% of all emissions. 

It's Not Only About Power and Transportation

The various industrial processes that use fossil fuels are also to blame.

For example, large quantities of natural gas are needed to produce the synthetic fertilizers used in conventional agriculture.  

Just the process of extracting and processing coal, natural gas, or oil involves the release of greenhouse gases - those activities make up 11% of the total emissions. This includes natural gas leaks during the extraction, transportation, and delivery phases.

Non-Fossil Fuel Greenhouse Gas Emissions

  • Cement production hinges on a chemical reaction that releases massive amounts of carbon dioxide.
  • Land clearing (for agriculture or other types of land use) exposes the soil which allows the release of carbon dioxide.
  • Deforestation, especially associated with burning, allows a lot of the carbon stored in tree roots, branches, and leaves to be released into the atmosphere. It's not a trivial amount: together, land clearing and burning account for 10% of all greenhouse gas emissions.
  • Methane (the main constituent in natural gas) is produced in large quantities by microorganisms present in rice fields, making rice production a significant contributor to climate change. And it's not just rice: lots of methane is also produced by cattle and other herbivorous livestock.
  • Temperatures are warming especially fast in Arctic regions, and there the thawing permafrost is releasing both carbon dioxide and methane. By 2100, it is estimated that 16 to 24% of the permafrost will have thawed, entering a vicious feedback loop: as permafrost thaws, it releases stored carbon dioxide and methane, which further warms the climate, melts more permafrost, and releases more greenhouse gases.

    Just as we create greenhouse gases, we can also take steps to reduce those emissions. It should becomes clear from reading this list that a whole suite of solution is necessary to tackle climate change, beginning with the switch to renewable energy. Responsible stewardship also means encouraging sustainable agricultural and forestry practices.

     

    Edited by Frederic Beaudry