It is difficult to measure accurately
each nation’s contribution of carbon dioxide to the Earth’s atmosphere. Carbon
is extracted out of the ground as coal, gas, and oil, and these fuels are often
exported to other countries where they are burned to generate the energy that
is used to make products. In turn, these products may be traded to still other
countries where they are consumed. A team led by the Carnegie Institution’s
Steven Davis, and including Ken Caldeira, tracked and quantified this supply
chain of global carbon dioxide emissions. Their work will be published online
by Proceedings of the National Academy of
Sciences.
Traditionally, the carbon dioxide
emitted by burning fossil fuels is attributed to the country where the fuels
were burned. But until now, there has not yet been a full accounting of
emissions taking into consideration the entire supply chain, from where fuels
originate all the way to where products made using the fuels are ultimately
consumed.
“Policies seeking to regulate emissions
will affect not only the parties burning fuels but also those who extract fuels
and consume products. No emissions exist in isolation, and everyone along the
supply chain benefits from carbon-based fuels,” Davis says.
He and Caldeira, along with Glen Peters
from the Center for International Climate and Environmental Research in Oslo, Norway,
based their analysis on fossil energy resources of coal, oil, natural gas, and
secondary fuels traded among 58 industrial sectors and 112 countries in 2004.
They found that fossil resources are
highly concentrated and that the majority of fuel that is exported winds up in
developed countries. Most of the countries that import a lot of fossil fuels
also tend to import a lot of products. China is a notable exception to
this trend.
Davis and Caldeira say that their
results show that enacting carbon pricing mechanisms at the point of extraction
could be efficient and avoid the relocation of industries that could result
from regulation at the point of combustion. Manufacturing of goods may shift
from one country to another, but fossil fuel resources are geographically
fixed.
They found that regulating the fossil
fuels extracted in China,
the U.S., the Middle East, Russia, Canada,
Australia, India, and Norway would cover 67% of global
carbon dioxide emissions. The incentive to participate would be the threat of
missing out on revenues from carbon-linked tariffs imposed further down the
supply chain.
Incorporating gross domestic product
into these analyses highlights which countries’ economies are most reliant on
domestic resources of fossil energy and which economies are most dependent on
traded fuels.
“The country of extraction gets to sell
their products and earn foreign exchange. The country of production gets to buy
less-expensive fuels and therefore sell less-expensive products. The country of
consumption gets to buy products at lower cost.” Caldeira says. “However, we
all have an interest in preventing the climate risk that the use of these fuels
entails.”
