Getting Warmer
Planes, Trains and Automobiles
14%
of total greenhouse gas emissions comes from transportation.
Source: World Resources Institute, Climate Analysis Indicators Tool
Hot Topic
The earth's surface temperature increased by about 1°F during the twentieth century - and it's only getting warmer. The past decade has seen some of the hottest years on record.
Scientists attribute the trend to a variety of factors, including those that are naturally occurring, such as changes in the sun's intensity and volcanic eruptions. But mounting evidence shows that human activity is also a major contributor to global warming, and left unchecked, could lead to devastating effects on climate patterns.
The World Resources Institute outlines several key implications of climate change:
- Intensified and more frequent weather events, like floods, droughts and hurricanes
- Rising sea levels
- Water and food supply shortages
- Disease and health problems
- Disruption of ecosystems
- Habitat destruction and species extinction
Key Projections
projected rise in global temperature by the end of this century, if there is no change in current policies
of the projected increase in energy-related CO2 emissions by 2030 comes from the power generation and transport sectors
of the projected increase in energy-related CO2 emissions by 2030 arises in China, India and the Middle East
Source: International Energy Agency, World Energy Outlook 2008
Top GHG Emitting Countries
The 25 countries with the largest GHG emissions account for about 83% of global emissions.
1. United States
2. China
3. European Union
4. Russia
5. India
Photo by Nick Humphries.
Source: World Resources Institute.
The Greenhouse Effect
The earth experiences a natural warming process, whereby sunlight is absorbed into the atmosphere and converted to heat. Gases such as carbon dioxide, methane and nitrous oxide trap some of the heat, similar to what occurs in a greenhouse. The rest is radiated back out into space, so that the earth stays at a comfortable temperature.
But humans have upset this natural balance by pumping more and more heat-trapping greenhouse gases into the air, mostly through the combustion of fossil fuels, like coal, oil and natural gas. This is what scientists call an "enhanced greenhouse effect," and it causes a rise in global temperatures.
To learn more about this process, visit the Pew Center on Global Climate Change, which publishes a chart of the major greenhouse gases and a diagram explaining how the greenhouse effect works.
Key Facts
of global GHG emissions comes from the United States, the largest emitter
of global GHG emissions come from China
countries contribute only 10 percent of annual emissions
Source: World Resources Institute.
What's in a Name?
People often switch between the terms "climate change" and "global warming" to describe the same thing: rising temperatures. But technically, there's a difference between the two meanings.
Climate change refers to significant alterations in a region's long-term weather patterns, like average temperature, precipitation or wind.
Global warming, on the other hand, refers specifically to the overall increase in the earth's temperature, which can in turn affect global climate patterns.
Taking Measure
Greenhouse gas emissions can be tracked at the global, regional and local levels through an emissions inventory, which is a measurement of the amount of greenhouse gases released into (or removed from) the atmosphere over a specific period of time. Policy makers can use greenhouse gas inventories to identify trends, as well as to develop reduction strategies.
States and countries prepare their own inventories, based on national and international guidelines. Companies and organizations can also measure the greenhouse gas emissions associated with their business operations. And individuals can track their own GHG footprint with the help of online calculators, such as the Environmental Protection Agency's Household Emissions Calculator.
The Intergovernmental Panel on Climate Change developed methodology guidelines for national greenhouse gas inventories and publishes assessment reports containing scientific and socio-economic information on humna-induced climate change.
And the World Resources Institute's Climate Analysis Indicators Tool (CAIT) provides a database of international greenhouse gas emissions data and other climate-relevant indicators.
Related Publications
Charts & graphs
 World GHG Emissions Flow Chart. Source: Climate Analysis Indicators Tool (CAIT), World Resources Institute. |  GHG Emissions from Transportation. Source: Climate Analysis Indicators Tool (CAIT), World Resources Institute |
