Carbon dioxide is not the only greenhouse gas, although it’s the one most scientists worry about on the long term scale. Its diversion out of deep storage into the active global carbon cycle is causing global warming, and that, the evidence strongly shows, is causing widespread and disruptive climate change.
But in short timeframes, methane is the gas on everybody’s worried lips. The sources of methane are affected by global warming, and methane emissions cause strong global warming in the short term, so it’s a positively augmenting feedback, self-amplifying, and causing grave concern in many environmental policy seminars.
People often point the finger at the digestive systems of ruminant livestock when they want to pinpoint a scapegoat for rising methane emissions, but they should perhaps look closer to their own bathrooms and kitchens and their underfloor gas pipelines.
Urban methane emissions matter, because increasingly, humanity is congregating in cities. Urban infrastructure develops over time and it’s hard to alter and repair, so its safety and efficiency can decline with age. Old cities with old habits and old pipework could be part of the reason why researchers recently found high methane emissions in Boston USA :-
“May 13, 2011 : Earlier this year, Boston University researchers and collaborators conducted a mobile greenhouse gas audit in Boston and found hundreds of natural gas leaks under the streets and sidewalks of Greater Boston…”
The urban management of human, animal, food and post-consumer waste are probably also in the top ten causes of excess urban emissions of methane.
Two obvious conclusions can be reached. First and foremost, it behoves the mayor of each major city to mandate that all biological waste should be properly collected and subject to anaerobic digestion or gasification – and the gas collected to prevent it becoming “fugitive” methane emissions. It’s better to burn biologically-sourced methane for energy, a Renewable Gas, than allowing the methane to quickly roast the Earth. It’s true that burning methane releases carbon dioxide, but this is from recently living things, not the bowels of the Earth, so it does not add net carbon dioxide to the atmosphere, like burning fossil fuels does.
The second major realisation is that cities will have to have well-funded programmes to renovate their gas grids and keep them well-monitored from now on. Piping the Renewable Gas from the new waste digestion and gasification plants into the city gas grids will make them less dependent on fossil Natural Gas, and pay for the grid improvements.
The measurement of fugitive urban emissions of methane points the way to move from climate insecurity to energy resilience – and that has to be a Good Thing.