GEOG 438W
Human Dimensions of Global Warming

Proximate Causes of Climate Change

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The Human Activities That Cause Climate Change

Proximate causes are the human activities that directly cause climate change.

The human causes of climate change fall into two categories: proximate causes and driving forces.

Proximate causes are the human activities that directly cause climate change. There are two overarching categories of proximate causes: land transformation and industrial processes. People transform the land surface in many ways, with some important types being deforestation, agriculture, urbanization, mining, reservoir building, land draining, and transportation network building. Industrial processes include energy production, transportation, manufacturing, construction, waste disposal, petrochemical, mineral, and food processing, and many other activities. All of these activities change the flux of energy and mass to the climate system.

In other words, proximate causes are the emissions and the land use changes that occur because of human activity.  We'll take a look at emissions by sector and the geography of emissions later in this unit.  While the graphic below is a static image, if you click the link to its home on WRI's site, you'll find that it's part of an interactive tool they've created called the Climate Data Explorer.  This allows you to drill down into a country's emissions profile and see what sectors and places are really most responsible for our changing climate.  As you take a look at the image below, what do you notice?  

  • Which countries have the bigger pieces of the global emissions pie?
  • Looking at any individual country, which sector or sectors are contributing the most to their emissions profiles?
WRI still image of an interactive graphic illustrating global GHGs by country and sector
Credit: World Resources Institute

There are two overarching categories of proximate causes: land transformation and industrial processes. People transform the land surface in many ways, with some important types being deforestation, agriculture, urbanization, and transportation network building. Industrial processes include energy production, transportation, manufacturing, waste disposal, and many other activities. Note that land transformation and industrial processes are not always distinct. For example, building a road transforms the land but requires powerful industrial equipment, mined materials, and processed chemicals. Once the road is built, vehicles traveling on it are manufactured using energy, petrochemicals, and mined materials, and are run by burning mined and processed petroleum products.

Human activities release GHGs to the atmosphere at unprecedented levels, trapping more of the longwave radiation for longer periods and forcing the surface temperature to rise. The gases most responsible for warming are three naturally occurring gases,carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The manufactured chemicals are collectively called the halocarbons and include chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and others. Focusing on the portion of warming caused by the natural gases released by human activity, carbon dioxide is responsible for 72 percent of the warming, methane for 18 percent, and nitrous oxide for 9 percent.

Pie charts showing greenhouse gases by sector & also by CO2, CH4, and N2O. See text version below.
Annual greenhouse gas emissions by sector.
Click here for a text description of this image
Annual Greenhouse Gas Emissions by Sector
Process Percentage of gas emitted
Industrial processes 16.8%
Power stations 21.3%
Waste disposal and treatment 3.4%
Land use and biomass burning 10.0%
Residential, commercial, and other sources 10.3%
Fossil fuel retrieval, processing, and distribution 11.3%
Agricultural byproducts 12.5%
Transportation fuels 14.0%

Carbon Dioxide (72% of total)
Process Percentage of gas emitted
Industrial processes 20.6%
Power stations 29.5%
Fossil fuel retrieval, processing, and distribution 8.4%
Land use and biomass burning 9.1%
Residential, commercial, and other uses 12.9%
Transportation fuels 19.2%

Methane (18% of total)
Process Percentage of gas emitted
Agricultural byproducts 40.0%
Residential, commercial, and other uses 4.8%
Land use and biomass burning 6.6%
Waste disposal and treatment 18.1%
Fossil fuel retrieval, processing, and distribution 29.6%<
Industrial processes 0.9%

Nitrous Oxide (9% of total)
Process Percentage of gas emitted
Agricultural byproducts 62.0%
Power stations 1.1%
Land use and biomass burning 26.0%
Industrial processes 5.9%
Waste disposal and treatment 2.3%
Residential, commercial, and other uses 1.5%
Transportation fuels 1.2%