The Earth is heating up. What did the EPA say are the top human causes of global warming?
As explained in graphics by the US Environmental Protection Agency here, the causes of global warming include increases in greenhouse gases such as CO2, methane and ozone, which trap heat in the atmosphere.
Editor’s Note: In 2017 officials in the Trump administration removed some EPA data from their web site, therefore some of the EPA links may bring up blank pages.
There are many things that contribute to this, but these greenhouse gas-trapping activities are the top causes of global warming (look below the chart for a breakdown of each, all figures courtesy of the EPA):
2015 chart courtesy of the EPA. Numbers based on global emissions from 2010, the latest available.
1. Electricity and heat production – 25%
Burning fossil fuels to generate electricity and heat is the single largest cause of global warming. And while developing countries are taking steps (albeit small steps) towards reducing these types of fuels, developing nations like China are expanding their usage of coal, gas, and oil for energy.
2. Industry – 21%
Industrial processes such as chemical, metal-manufacturing, and mineral transformation emit a huge amount of greenhouse gases – especially considering that this figure does not include greenhouse gas emissions from generating energy (they’re included in the figure from #1).
3. Agriculture, land use and forestry – 24%
In the Amazon alone, more than 10,400 square miles of forest is lost every year due to logging, mining, and land conversion. These processes emit greenhouse gases through energy use and peat soil fires, and also reduce the mitigating effect that CO2-absorbing trees have on global warming.
Fossil fuel use by agricultural machines, biomass burning, and methane released by the enteric fermentation (release of digestive gases) of livestock all contribute to make agriculture one of the world’s top greenhouse gas sources.
4. Transportation – 14%
This includes petroleum-based fuels burned for road, rail, air, and marine transportation, both for individual and industrial purposes. In the US, passenger cars make up the largest single portion (34%) of emissions, followed by light and heavy trucks.
5. Buildings – 6%
These emissions come from on-site energy production, cooking in homes and heating buildings.
6. Other – 10%
Includes emissions associated with energy resources such as mining, extraction and processing.
More understanding can be found in our Earth Matters focus area about climate change.