The Global Reach of Urban GHG Footprints

Greenhouse gas emissions caused by urban households' purchases of goods and services from beyond city limits are much bigger than previously thought.  These upstream emissions may occur anywhere in the world.

Greenhouse gas emissions caused by urban households' purchases of goods and services from beyond city limits are much bigger than previously thought.  These upstream emissions may occur anywhere in the world and are roughly equal in size to the total emissions originating from a city's own territory, a new study shows.  This is not bad news but in fact offers local policy-makers more leverage to tackle climate change, the authors argue in view of the UN climate summit COP23 that just started.  They calculated the first internationally comparable greenhouse gas footprints for four cities from developed and developing countries:  Berlin, New York, Mexico City, and Delhi.  Contrary to common beliefs, not consumer goods like computers or sneakers that people buy are most relevant, but housing and transport - sectors that cities can substantially govern.

"It turns out that the same activities that cause most local emissions of urban households - housing and transport - are also responsible for the majority of upstream emissions elsewhere along the supply chain," says lead-author Peter-Paul Pichler from the Potsdam Institute for Climate Impact Research (PIK).  "People often think that mayors cannot do much about climate change since their power is restricted to city limits, but their actions can have far-reaching impacts.  The planned emission reductions presented so far by national governments at the UN summit are clearly insufficient to limit global warming to well below 2 degrees Celsius, the target agreed by 190 countries, therefore additional efforts are needed."

Housing and transport cause most city emissions, locally but also upstream

Cement and steel used for buildings take a huge amount of energy - typically from fossil fuels - to be produced, for instance.  If a city instead chooses to foster low carbon construction materials this can drastically reduce its indirect CO2 emissions.  Even things that cities are already doing can affect far-away emissions.  Raising insulation standards for buildings for example certainly slashes local emissions by reducing heating fuel demand.  Yet it can also turn down the need for electric cooling in summer which reduces power generation and hence greenhouse gas emissions in some power plant beyond city borders.

Read more at The Global Reach of Urban GHG Footprints