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We may have to abandon concrete to fight climate change, architectural experts say
The building material seems so ubiquitous — what can we use in its place?
- Concrete is a surprisingly dangerous contributor of greenhouse gas emissions.
- For years, architects haven't been concerned with these emissions since concrete buildings last for so long; their carbon footprint is spread out over their entire lifespan.
- However, as we approach climate "tipping points," the front-loaded cost of concrete construction may be too high.
"If we invented concrete today, nobody would think it was a good idea," said architectural engineer and panel member Michael Ramage. "We've got this liquid and you need special trucks, and it takes two weeks to get hard. And it doesn't even work if you don't put steel in it."
The four billion tons of concrete produced for construction each year accounts for 8 percent of the world's carbon dioxide emissions, mainly through the production of clinker. Clinker serves as a crucial binding element in cement, the primary ingredient of concrete, and is produced by heating limestone and clay to around 1,400°C (about 2,500°F). Heating limestone (CaCO3) to these temperatures, however, causes a chemical reaction called calcination that results in lime (CaO) and carbon dioxide (CO2) as a waste product. Roughly half of concrete's carbon dioxide emissions is due to calcination, while another 40 percent comes from burning fossil fuels to heat up limestone to the point where this chemical reaction can occur. The last 10 percent comes from the fuel used in the mining and transportation process.
Eight percent might seem like a large slice of the world's carbon dioxide pie, but architectural experts haven't been particularly concerned about this figure until recently. The reason why has to do with concrete's longevity. Normally when calculating a building's total carbon emissions, said Phineas Harper of Dezeen magazine, architects take the amount of carbon needed to construct a building and divide it over the building's total lifespan. "That gives you your per-year carbon emissions," said Harper. However, in our current climate situation, this kind of thinking is "dead wrong."
Had we taken climate change more seriously a hundred years ago, this would probably be fine. But as it stands today, we have only a few short years before we reach climate "tipping points," events that create negative feedback loops in the climate that are very difficult to reverse. The melting of polar ice, which reflects sunlight and contains locked-away greenhouse gases, is a well-known example of such a tipping point. So too is deforestation in rainforests, which increases the likelihood of local droughts, killing even more trees.
As a result, the front-heavy carbon load of concrete buildings inadvertently contribute more to climate change than any straightforward calculation may suggest.
Looking for alternatives
So, if we can't build sustainably with concrete, what other materials can we build with? Ken de Cooman, founder of BC Architects & Studies, discussed how his firm is using materials primarily formed from the earth, like compressed-earth bricks. There are also biocomposite materials, which are formed out of natural fibers embedded in a matrix. Hempcrete, for instance, is a biocomposite of hemp and lime that is actually carbon negative since hemp absorbs CO2 as it grows.
Interestingly, one of the best candidates for replacing concrete in construction projects is something of an old-fashioned solution — timber. One might wonder if using timber is all that wise given the importance of forests in maintaining the health of our environment, this might seem counterintuitive. Ramage acknowledged that building out of timber would require sustainable practices. In order to make construction using timber sustainable, a number of trees would have to be planted for every tree that is cut down. And, added Ramage,"It's important to remember that every kilogram of timber we build with holds the equivalent of 1.8 kilograms of carbon dioxide." Unlike concrete, timber stores carbon dioxide, lowering a building's overall carbon footprint.
A photo of Andrew Waugh's all-timber building constructed in North London.
Image source: Architecture of Emergency, 2019
As an example of this, architect Andrew Waugh described a building his firm built in North London.
"We built the entire building from solid timber from the first floor up. So all the internal walls, external walls, lift shafts, staircases, all in timber. … It's about 2.8 trees per person that live in that building and for every one of those trees that was cut down to build that building five more were planted in its place."
Timber is growing in popularity as a construction material, both because of its greater sustainability and because of advances that have enabled it to be used in taller buildings, like cross-laminated timber. These developments have not left the concrete industry too happy, which has taken out advertisements emphasizing the flammability of timber buildings and the environmental impacts of cutting down trees.
"We must be doing something right," said Waugh, "because, much like the tobacco industry in the 1980s and 1990s, Big Concrete is beginning to fight back."
Many of the methods we can employ to address climate change can seem radical. After all, many climate change activists ask that we stop engaging in many activities that have been a part of our lives for decades. But the climate crisis didn't suddenly arise out of nowhere — it's these activities that have, bit by bit, added momentum to this phenomenon.
Reversing that momentum will mean cutting back on fossil fuels, eating meat, building in concrete, and many more activities that we have taken for granted.
Update Tuesday, October 15, 2019: This story was updated to specify when and how carbon emissions are released during the cement production process.
What is human dignity? Here's a primer, told through 200 years of great essays, lectures, and novels.
- Human dignity means that each of our lives have an unimpeachable value simply because we are human, and therefore we are deserving of a baseline level of respect.
- That baseline requires more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose.
- We look at incredible writings from the last 200 years that illustrate the push for human dignity in regards to slavery, equality, communism, free speech and education.
The inherent worth of all human beings<p>Human dignity is the inherent worth of each individual human being. Recognizing human dignity means respecting human beings' special value—value that sets us apart from other animals; value that is intrinsic and cannot be lost.</p> <p>Liberalism—the broad political philosophy that organizes society around liberty, justice, and equality—is rooted in the idea of human dignity. Liberalism assumes each of our lives, plans, and preferences have some unimpeachable value, not because of any objective evaluation or contribution to a greater good, but simply because they belong to a human being. We are human, and therefore deserving of a baseline level of respect. </p> <p>Because so many of us take human dignity for granted—just a fact of our humanness—it's usually only when someone's dignity is ignored or violated that we feel compelled to talk about it. </p> <p>But human dignity means more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose—a freedom that can be hampered by restrictive social institutions or the tyranny of the majority. The liberal ideal of the good society is not just peaceful but also pluralistic: It is a society in which we respect others' right to think and live differently than we do.</p>
From the 19th century to today<p>With <a href="https://books.google.com/ngrams/graph?year_start=1800&year_end=2019&content=human+dignity&corpus=26&smoothing=3&direct_url=t1%3B%2Chuman%20dignity%3B%2Cc0" target="_blank" rel="noopener noreferrer">Google Books Ngram Viewer</a>, we can chart mentions of human dignity from 1800-2019.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0ODU0My9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY1MTUwMzE4MX0.bu0D_0uQuyNLyJjfRESNhu7twkJ5nxu8pQtfa1w3hZs/img.png?width=980" id="7ef38" class="rm-shortcode" data-rm-shortcode-id="9974c7bef3812fcb36858f325889e3c6" data-rm-shortcode-name="rebelmouse-image" />
American novelist, writer, playwright, poet, essayist and civil rights activist James Baldwin at his home in Saint-Paul-de-Vence, southern France, on November 6, 1979.
Credit: Ralph Gatti/AFP via Getty Images
The future of dignity<p>Around the world, people are still working toward the full and equal recognition of human dignity. Every year, new speeches and writings help us understand what dignity is—not only what it looks like when dignity is violated but also what it looks like when dignity is honored. In his posthumous essay, Congressman Lewis wrote, "When historians pick up their pens to write the story of the 21st century, let them say that it was your generation who laid down the heavy burdens of hate at last and that peace finally triumphed over violence, aggression and war."</p> <p>The more we talk about human dignity, the better we understand it. And the sooner we can make progress toward a shared vision of peace, freedom, and mutual respect for all. </p>
With just a few strategical tweaks, the Nazis could have won one of World War II's most decisive battles.
- The Battle of Britain is widely recognized as one of the most significant battles that occurred during World War II. It marked the first major victory of the Allied forces and shifted the tide of the war.
- Historians, however, have long debated the deciding factor in the British victory and German defeat.
- A new mathematical model took into account numerous alternative tactics that the German's could have made and found that just two tweaks stood between them and victory over Britain.
Two strategic blunders<p>Now, historians and mathematicians from York St. John University have collaborated to produce <a href="http://www-users.york.ac.uk/~nm15/bootstrapBoB%20AAMS.docx" target="_blank">a statistical model (docx download)</a> capable of calculating what the likely outcomes of the Battle of Britain would have been had the circumstances been different. </p><p>Would the German war effort have fared better had they not bombed Britain at all? What if Hitler had begun his bombing campaign earlier, even by just a few weeks? What if they had focused their targets on RAF airfields for the entire course of the battle? Using a statistical technique called weighted bootstrapping, the researchers studied these and other alternatives.</p><p>"The weighted bootstrap technique allowed us to model alternative campaigns in which the Luftwaffe prolongs or contracts the different phases of the battle and varies its targets," said co-author Dr. Jaime Wood in a <a href="https://www.york.ac.uk/news-and-events/news/2020/research/mathematicians-battle-britain-what-if-scenarios/" target="_blank">statement</a>. Based on the different strategic decisions that the German forces could have made, the researchers' model enabled them to predict the likelihood that the events of a given day of fighting would or would not occur.</p><p>"The Luftwaffe would only have been able to make the necessary bases in France available to launch an air attack on Britain in June at the earliest, so our alternative campaign brings forward the air campaign by three weeks," continued Wood. "We tested the impact of this and the other counterfactuals by varying the probabilities with which we choose individual days."</p><p>Ultimately, two strategic tweaks shifted the odds significantly towards the Germans' favor. Had the German forces started their campaign earlier in the year and had they consistently targeted RAF airfields, an Allied victory would have been extremely unlikely.</p><p>Say the odds of a British victory in the real-world Battle of Britain stood at 50-50 (there's no real way of knowing what the actual odds are, so we'll just have to select an arbitrary figure). If this were the case, changing the start date of the campaign and focusing only on airfields would have reduced British chances at victory to just 10 percent. Even if a British victory stood at 98 percent, these changes would have cut them down to just 34 percent.</p>
A tool for understanding history<p>This technique, said co-author Niall Mackay, "demonstrates just how finely-balanced the outcomes of some of the biggest moments of history were. Even when we use the actual days' events of the battle, make a small change of timing or emphasis to the arrangement of those days and things might have turned out very differently."</p><p>The researchers also claimed that their technique could be applied to other uncertain historical events. "Weighted bootstrapping can provide a natural and intuitive tool for historians to investigate unrealized possibilities, informing historical controversies and debates," said Mackay.</p><p>Using this technique, researchers can evaluate other what-ifs and gain insight into how differently influential events could have turned out if only the slightest things had changed. For now, at least, we can all be thankful that Hitler underestimated Britain's grit.</p>
We’ve mapped a million previously undiscovered galaxies beyond the Milky Way. Take the virtual tour here.
See the most detailed survey of the southern sky ever carried out using radio waves.
Astronomers have mapped about a million previously undiscovered galaxies beyond the Milky Way, in the most detailed survey of the southern sky ever carried out using radio waves.
A new study shows our planet is much closer to the supermassive black hole at the galaxy's center than previously estimated.
Arrows on this map show position and velocity data for the 224 objects utilized to model the Milky Way Galaxy. The solid black lines point to the positions of the spiral arms of the Galaxy. Colors reflect groups of objects that are part of the same arm, while the background is a simulation image.
Apple sold its first iPod in 2001, and six years later it introduced the iPhone, which ushered in a new era of personal technology.