Monday, February 10, 2014

Have Humans Become a Climate Change "Feedback Mechanism"?

In case you're wondering, we're considered a "positive feedback"

From Australia to California, Atlanta to London, climate change has settled in as a more or less permanent fixture.  Australia is roasting, California is parched, Atlanta was frozen solid and London is staring into the face of severe and perpetual flooding.  What to do, what to do?

The lead editorial in The Guardian proclaims climate change as "weather of Olympian extremes."

Even before 1988, when global warming first became an item on the international agenda, climate scientists had begun to warn that, were average temperatures to rise with greenhouse gas levels, then extremes would become more damaging, more frequent, or both.

Since then, the warnings have multiplied, and intensive and sustained research by scientists in Britain, Europe, China, Australia and the US has told the same story: if there are no steps to reduce greenhouse emissions, then average global temperatures will continue to rise, and extremes of heat and cold, of evaporation and precipitation, will continue. And yet each extreme triggers new energy demand.

Sea defences, river dredging and the pumping of water from flooded farmland all consume expensive energy. The alternative is catastrophic loss; by 2100, according to a European study this month, without adaptation, storm surge damage to coastal cities could total $100 trillion a year.

In a blizzard, cities and homesteads have no choice but to turn up the thermostat. As summer temperatures soar, so will the demand for air conditioning: the US today uses about as much electricity to cool its offices, malls and homes as it did in the 1950s to supply the needs of the whole nation for all purposes.

In a cycle of positive feedback, demand for fossil fuels will continue to grow, and temperatures will continue to rise.

Say what?  Storm surge damage could soar to $100-Trillion a year, as in with a "T"?  What this editorial appears to suggest is that we're now locked in.  Ever worsening climate change impacts will compel us to consume ever more fossil fuel in adaptation efforts.  We've long known of feedback mechanisms - the disappearance of polar ice, the thawing and burning of the tundra, the release of Arctic methane - but now we, mankind, have become a positive feedback unto ourselves?

When is extreme weather no longer 'extreme'?  Perhaps when it becomes the new "normal."  By now most of us will have learned of the devastating storms, heavy rains and flooding that have beset Ireland and the southern half of England.  The chief scientist at Britain's Met Office, Dame Julia Slingo, has warned this is what Britain can expect from climate change over the next 20-years.

Colin Thorne, the chair of physical geography at Nottingham University, writes that the flooding scenario Britain's former chief scientist, Sir David King, warned ten years ago would hit the U.K. in 2030 has arrived prematurely and very unexpectedly.  The choices, says professor Thorne, are bleak.

What are the "hard choices" to which King alluded in 2004? Perhaps the best way to consider them is in relation to the three major causes of flooding: coastal, river, and surface water.

The enormous volumes of water and geographical scale of coastal flooding set it apart from the other two and, as an island nation with extensive areas of densely populated, low-lying land along our coasts and estuaries, we are especially vulnerable. Let's be clear: we cannot hold the line everywhere – it would cost too much and would destroy irreplaceable shoreline ecosystems through "coastal squeeze".

The Dutch take coastal protection very seriously indeed and they're very good at it too – even they now plan for and allow their coast to adjust to accommodate changing tides, waves and currents through "managed retreat". No, the future for coastal management in the UK will involve realigning defences by retiring them landward. The difficult choices for government are not in deciding where, or how much to retreat, but rather in finding equitable ways to relocate and, perhaps, compensating those affected for their financial losses and personal sacrifices.

Thorne sees a variety of options available to respond to river flooding but urban flooding poses real challenges.

Our cities rely largely on Victorian pipe and surface drains, often combined with sewer systems (Combined Sewer Overflows, or CSOs), that were never designed to handle rainstorms with the intensity and duration to which they're now subjected. When a CSO occurs, raw sewage mixed with flood water enters our streams and may overflow into our communities. The first hard decision is to separate storm water from sewage – this reduces the damage, misery and health impacts of urban flooding but at a considerable replacement cost. People say this can't be done – we must not believe them. Portland, Oregon, proves it can be done. In 2008 as part of a city-wide "gray to green initiative", they decided to get rid of their main CSO; just six years later, it's gone, and good riddance.

That's a huge investment, a particularly bitter pill for an austerity-obsessed government like David Cameron's to swallow.  It's a problem shared by every industrialized nation and Canada is no exception.  It has been estimated that upgrading Canada's essential infrastructure to withstand the impacts of climate change that are heading our way would be upwards of a trillion dollars.  Look for that in Jimbo Flaherty's budget.

Professor Thorne also explains that flooding has to be recognized for what it can offer to regions that face cyclical floods and drought. reinventing the way we manage the urban water cycle and making it a lot more like the natural cycle – recharging aquifers and surface-water stores in times of abundance to get us through what are likely to be increasingly frequent and protracted droughts. This is what Prof Cedo Maksimovic of Imperial College calls the blue-green dream. The "blue-green city" will use green spaces and corridors that turn blue during floods – reducing pressures on the pipe network while providing a wealth of benefits to citizens the rest of the time. The "Blue-Green Cities Research Consortium" is working out how this can be achieved, using Newcastle (ravaged by the Toon Monsoon in 2012, as its case study. Think it can't be done? Ask the people of Melbourne – they're at least a decade ahead of us, and their experience is just as compelling as Portland's move away from CSOs.

1 comment:

Purple library guy said...

I'm not so sure about that feedback mechanism. It presupposes business as usual except for a bit more energy used for heating and cooling.

But business is unlikely to be as usual. Homeless people use no air conditioning.