Lots of shoes make for big carbon feet

China is by far the largest “exporter” of carbon dioxide emissions, as seen in this map of the net flow of emissions embodied in trade among the major exporting and importing countries. Arrows indicate direction and magnitude of flow; numbers are megatons (millions of tons). Credit: Steven Davis/Carnegie Institution for Science

Goods bought in the richest parts of the world effectively export CO₂ emissions to poorer countries, a factor overlooked by governments’ climate change strategies. That’s the message coming from research in the news this month performed by two separate groups of researchers, one in the US and one in Norway. The Norway-based team of Edgar Hertwich and colleague Glen Peters in particular note that the carbon footprint continues to grow steadily in parallel with how much consumers spend. “There is no flattening out, no indication that the carbon footprint stabilizes at some point,” they write. Consequently, as nations continue to strive to raise their wealth, we might expect their carbon footprint to grow along with it. “This is, I’m afraid, bad news,” Peters and Hertwich say. “We cannot expect that emissions are reduced as a part of normal development.”

Hertwich and Peters last week won an award for the “Best Policy Paper” for 2009 from the journal Environmental Science and Technology that published their work. They looked at all countries’ carbon footprint in 2001, going further than just looking at CO₂ produced within their borders to also assess the impact of international trade for the first time. Their results have been made into a website, called “Carbon Footprint of Nations”, which shows how emissions vary with consumption. Greenhouse gas emissions rise about 70% with each doubling of consumer spending, with more emissions coming from transport and consumer goods and less from food.

The “Carbon Footprint of Nations” website created by Edgar Hertwich and Glen Peters shows international emissions in 2001.

On March 8 Ken Caldeira and Steven Davis at the Carnegie Institution in Stanford, California, also published a similar analysis of carbon footprints in 2004 in the Proceedings of the National Academy of Sciences. The study finds that, in 2004, 23% of global CO₂ emissions, or 6.2 billion tons, were used to produce goods traded internationally. Per person, about 2.5 tons of CO₂ are consumed in the U.S. but produced somewhere else. For Europeans, the figure can exceed four tons per person. Most of these emissions are outsourced to developing countries, especially China, where 22.5% of  the CO₂ produced was for goods to be exported. “There is little evidence that carbon-intensive industries are being sited in developing countries in direct response to climate policy,” Caldeira and Davis write. “However, industrial expansion occurring in those countries may unintentionally undermine ongoing efforts to regulate emissions.”

“Where CO₂ emissions occur doesn’t matter to the climate system,” Davis says. “Effective policy must have global scope. To the extent that constraints on developing countries’ emissions are the major impediment to effective international climate policy, allocating responsibility for some portion of these emissions to final consumers elsewhere may represent an opportunity for compromise.”

Hertwich and Peters suggest that improving production efficiency and using more renewable energy when manufacturing goods would also be useful. Nevertheless, they still seem uncertain that this will achieve enough. “If we really want to reduce climate change, it seems like the consumption of goods needs to be limited,” they write. This would not mean a complete halt, however, as the scientists note that consumption by rich households in both developing and industrialised nations is needed.

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