Climate Crisis: Rising Tides and Sinking Cities

climate_changetideWith all the population, urban sprawl, and consumption that we as a species are imposing on the planet, there are those who argue that we’ve entered a new geological era – known as the Anthropocene. It’s an age we’ve lived in since the neolithic revolution and the advent of farming, one where the human race is the dominant force shaping our planet. Since the industrial revolution, this era has been accelerating and escalating, and things are not likely to get better anytime soon.

It is because of this that we need to contemplate what the near future will look like. Consider the recent floods in the Canadian Prairies, or last year’s wildfires which raged across the American midwest. Consider the famines and shortages that led to a world food price crisis in 2007-8 which had serious political consequences, especially in the Middle East (i.e. the Arab Spring).

climate_changesandyWhen you add to this the fact that rising tides and the increased risk of storms are already effecting coastal communities in severe ways, you begin to understand just how turbulent the next few decades are likely to be. Already, incidents like Hurricane Katrina and Sandy, which rocked the Gulf of Mexico and the Eastern Seaboard in just the past decade, have shown just how extensive the damage can be.

Historically speaking, cities have been built in fertile river valleys and at river mouths to take advantage of fertile conditions, maritime resources and trade. Agricultural run-offs of sediment, water and nutrients created rich coastal deltas that could support greater food production. This and the good maritime and river connections for trade and transport made these ideal places to live.

Population_curve.svgBut as populations grew, rivers were tapped and diverted for irrigation, industry and canal transport. They were also trapped behind dams and reservoirs for energy and water storage, and depleted by droughts and other extractions. Meanwhile groundwater is increasingly being extracted from beneath cities, and sea levels are rising because of the run-off from the melting of glaciers and thermal expansion of the oceans.

As a result of these changes, many major cities are slowly sinking into the oceans. Our rapid industrialization over the past century has sped these processes, so that now, many urban centers face inundation by storm surges, and we stand to lose many of the most economically important parts of our planet. The loss of these cities will mean a terrible loss of life, economic fallout, and a massive refugee crisis.

Population_densityCities from Bangkok to New York have already experienced emergency flood conditions, and many more are to follow. Those most at risk include Mumbai, Guangzhou, Shanghai, Miami, Ho Chi Minh City, Calcutta, New York City, Osaka-Kibe, Alexandria and New Orleans. More than 3 billion people currently live in coastal areas at risk of global warming impacts such as rising sea levels – a number expected to rise to 6 billion by 2025.

And as was recently learned, the carbon levels in the upper atmosphere have surpassed 400 ppm (parts per million). The last time the atmosphere boasted this concentration of greenhouse gases was the Pliocene Era, a time when sea levels were as much as 60 to 80 feet higher than they current are. If sea levels rise to that level again, we can say goodbye to all these major cities, as well as any that sit on major waterways.

climate_changeshanghaiIt’s not just a matter of water rising up to swallow the coastlines, you see. As the flooding in southern Alberta and the Canadian Prairies demonstrated this week, there’s also the threat of flooding due to increased precipitation and of sewage systems backing up from increased storms and rainfall. These threats make shoring up river deltas and waterways effectively useless, since its not simply a matter of blocking the tides and rivers.

In terms of solutions, a number of major cities are investing in new sea walls, dykes and polders, or high-tide gates – like London’s Thames Barrier – to hold back high waters. In poorer places, people simply endure the problem until they are forced to abandon their homes. As the problem gets worse though, coordinated efforts to rescue people caught in flood zones will need to be mounted.

climate_changedykesAnd there are those who speculate that underwriting the damage will be a waste of time, since no government will be able to afford to compensate its citizens for the untold billions in property damage. In reality, many of these place will simply have to be abandoned as they become unlivable, and those forced out resettled to higher ground or protected communities.

At this point in any lecture on the fate of our planet, people are about ready to abandon hope and hang themselves. Hence, I should take this opportunity to point out that plans for dealing with the problem at the root – cutting our carbon footprint – are well underway. In addition to clean energy becoming more and more feasible commercially, there are also some very viable concepts for carbon capture.

These include inventions like artificial trees and ecoengineering, which will no doubt become absolutely essential in coming years. At the same time though, urban planning and architecture are beginning to embrace a number of alternative and clean technology concepts as part of their design. Not only will future buildings be designed to provide for the needs of their residents – food, water, electricity – in sustainable ways, they will also incorporate devices that can trap smog and turn it into biofuels and other useful products.

Of this, I will be saying more in the next post “Thinking, Breathing Cities of the Future”. Stay tuned!

Source: bbc.com

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