Greenhouse Gas Emissions...
Our
"tons of greenhouse gases" rating gives you an estimate
of each vehicle's impact on climate change. One of the most important
things you can do to reduce climate change pollution is buy a vehicle
with higher fuel economy.
Scientific evidence
strongly suggests that the buildup of greenhouse gases in the atmosphere
is raising the earth's temperature and changing the earth's climate
- both have many potentially serious consequences. Transportation,
specifically the combustion of fossil fuels in our vehicles, is
the single largest source of human-made greenhouse gases. The more
fuel your vehicle burns the more greenhouse gases it emits. Our
estimates assume you drive a certain number of miles each year,
but you can customize these assumptions to match your own driving
patterns by selecting the customize option at the top of each vehicle
page.
You may be surprised
to know that most vehicles produce several times their weight in
greenhouse gases each year. Not only does most of the fuel you put
in your tank become greenhouse gas emissions, but the carbon in
the fuel combines with oxygen in the air, almost tripling the weight
of the fuel itself.
The
greenhouse gas estimates presented here are "full fuel-cycle
estimates" and include the three major greenhouse gases emitted
by motor vehicles: carbon dioxide, nitrous oxide, and methane. Full
fuel-cycle estimates consider all steps in the use of a fuel, from
production and refining to distribution and final use. This gives
a more complete picture of how using a particular fuel contributes
to climate change.
Numerous
assumptions and calculations are necessary to estimate full fuel-cycle
greenhouse gas emissions in carbon dioxide equivalents. Because
of this, estimates from different sources will vary somewhat. Our
estimates are taken from the U.S. Department of Energy's GREET model,
version 1.7 developed by Argonne National Laboratory. Additional
information is available at:
http://www.transportation.anl.gov/ttrdc/greet/
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