Seawalls for a Distracted Planet

 

Nature doesn’t care if war rages in Ukraine, Myanmar continues its genocide against Rohingya, massive violence and starvation continue in Yemen and Somalia or that cartels and gangs continue to decimate El Salvador and Mexico. Climate change keeps getting worse. These conflicts are sending toxins into the air, accelerating greenhouse gasses, all justifying allowing corporations to return to greater dependence on fossil fuels… and the world is distracted. A February 27th Report from the World Resources Institute admonishes us: “Climate change is already causing widespread disruption in every region in the world with just 1.1 degrees C (2 degrees F) of warming.

“Withering droughts, extreme heat and record floods already threaten food security and livelihoods for millions of people. Since 2008, devastating floods and storms have forced more than 20 million people from their homes each year. Since 1961, crop productivity growth in Africa shrunk by a third due to climate change.”  

Experts predict that by the end of the century, even forgetting about the fires, floods, desertification and searing temperatures, seas in some coastal communities may rise by 18 feet projecting a 1.5C degree rise (2.7F) by then. The rise will happen gradually, as we are already witnessing here in the United States in the most obvious reality now facing southern Florida, where even normal rains and higher surf flood city streets all the time.

We have all kinds of “clever solutions,” many posited by politicians without any scientific basis and less engineering experience. Stuff like “raise the streets” or build seawalls like the ones in the Netherlands. There are just too many valuable coastal areas to believe that mankind can “simply build seawalls,” a high cost to be sure, but one that too many believe will save important coastal cities. Possible? Sure. Money would have to come from somewhere, and a whole lot of needed infrastructure and social needs would have to be diminished. We would also have to deal with wars over resources, like water, food (desertification will remove a lot of arable land) and others of earth’s valuables.

The big question is exactly what would be used to build those massive containment walls? The natural answer to that seemingly common construction problem is “concrete.” What few people know is that the use of concrete has always been a massive contributor to greenhouse gas emissions. In a study (Concrete fuels climate change – but there’s a nature-friendly way to defend coasts from rising seas) report in the March 22nd TheConveresation.com, Ravindra Jayaratne, Reader in Coastal Engineering, University of East London, and Ali Abbas, Associate Professor of Structural Engineering, University of East London, explain this concrete conundrum and possible ways to use alternative building materials:

“Paradoxically, these [sea]walls which are designed to protect people from the consequences of global heating also contribute to it. We estimated the emissions involved in creating north-eastern Japan’s concrete breakwaters [Fukushima and Iwate prefectures, including the new wall pictured above] at around six million tonnes of CO₂ by taking into account their size and length and using industry-standard tools…

“Concrete is the most common material for making breakwaters. Cement, the main binder in a concrete mix, is primarily made of clinker – a residue produced by firing limestone and clay in a furnace heated to 1,450°C. Creating that much heat is typically done by burning fossil fuels, emitting greenhouse gases in the process.

“Cement making is responsible for about 7% of annual CO₂ emissions. But without concrete, many of the world’s most impressive buildings and structures – such as Australia’s Sydney Opera House and the Hoover Dam in Las Vegas – wouldn’t exist. One of the biggest challenges facing the construction sector is reducing concrete’s carbon footprint while keeping the benefits of a cheap and durable building material.

“One way to achieve this is by replacing cement with recycled industrial waste, such as granulated slag from steelworks and pulverised ash from coal power plants (essentially, the residue that can be scraped out of the bottom of furnaces)… Our newly designed low-carbon concrete mixes use both of these recycled materials. In fact, it was possible to use up to 60% steel furnace waste in the mixes without the concrete losing its compressive strength, which is crucial for ensuring the structure holds up. The resulting mixes had a 40% smaller carbon footprint than traditional concrete.

“Our designs also use steel fibres akin to hairpins that can be added to the concrete mix, eliminating the need to assemble vast steel mesh grids. The costs and emissions of construction are lower as a result, and the final product is just as strong as a traditional breakwater… Concrete breakwaters can even stimulate biodiversity. Some are textured in such a way that they mimic reef habitats, encouraging the settlement and growth of marine plants and animals in their grooves and protruding surfaces.” A reduction in concrete’s carbon footprint but hardly zero emissions solution. That would take a vastly more serious concerted global effort to contain emissions. And exactly how does a world at war, involving world powers which are major emitters of greenhouse gasses, do that? Exactly.

I’m Peter Dekom, and even when we have excused to slow down on using fossil fuels and containing greenhouse gases, remember that nature doesn’t care about excuses and justifications; the laws of physics and chemistry simply continue.