Growing the Limestone for Climate-Friendly Concrete
Concrete is the most prolific man-made material on the planet, and as a result, its production is one of the most significant contributors to climate change.
The concrete production process involves burning quarried limestone at temperatures higher than 2,500 degrees Fahrenheit (1,400 degrees Celsius), which emits carbon dioxide. The entire process creates about 8 percent of global greenhouse gas emissions.
But a group of scientists at the University of Colorado-Boulder believe they have found a way to make concrete production carbon neutral, with a balance between carbon stored and emitted, and possibly even carbon negative, with more carbon stored than emitted.
The key is using limestone that is grown rather than quarried. Here’s how it works: microalgae called “coccolithophores” use photosynthesis to convert atmospheric carbon dioxide into calcium carbonate shells, or an “armor of limestone,” as Wil Srubar, the lead principal investigator on the project, calls it. These limestone shells can be harvested and burned, which still releases carbon dioxide, but only that which was consumed and stored by the algae. That makes the process carbon neutral.
The process can be made carbon negative by replacing up to 15 percent of the cement that is mixed to make concrete with carbon-neutral ground limestone. The hardened concrete locks that carbon in, permanently removing it from the atmosphere.
The U.S. Department of Energy recently awarded Srubar and his team $3.2 million to develop and scale up their alternative concrete. What makes it different from other low-carbon concrete alternatives, Srubar said, is the ability to manufacture the product through the current concrete production process.
“We’re just asking the cement and concrete industry to switch sources of limestone from the geological sources that they use today to biological sources that we can actually grow today,” said Srubar.
If all the world’s concrete production used grown limestone instead of quarried limestone, Srubar estimates that about 2 gigatons of greenhouse gas emissions would be avoided annually. To get to the level of commercial production needed to meet the United States’ needs, he said about 1 million to 2 million acres of open ponds will be needed to grow the coccolithophores. That’s about 1 percent of the land area currently used to cultivate corn in the country.
“Our aspiration is to build and operate the world’s largest coccolithophore farm,” Srubar said. “At the end of the day, we’re farming algae and we’re farming limestone.”
How Climate Change Affects Seafood Choices
Restaurants in Vancouver are serving seafood species that favor warmer ocean waters compared to restaurants that operated in the city a century ago. That’s based on menus from restaurants dating back to the 1880s.
A team of researchers from the University of British Columbia collected 362 menus from Vancouver seafood restaurants over the past 130 years, sourced from the internet and museums. They identified the marine species available for diners and the water temperature that each species preferred to inhabit. With this information, the researchers created an index for the average temperature preference of seafood served over different time periods.
They found that the average preferred temperature increased by about 5.6 degrees Fahrenheit (3.1 degrees Celsius), according to their findings published earlier this year in the journal Environmental Biology of Fishes.
“That means that there was increasing dominance or increasing occurrence of species of seafood that naturally would prefer warmer water,” said study co-author William Cheung, a professor at the University of British Columbia. “We related that to the changes in sea water temperature in the waters around British Columbia and we find that that increasing ocean temperature is related to the increasing temperature of a seafood menu.”
For example, Humboldt squid, a warmer water species, has found its way on some Vancouver menus in recent decades when it was not present on older menus at all.
Cheung said that looking at old menus was an interesting and unique way to understand how climate change has affected the human experience over time. He hopes these findings help bring more awareness and concern to people who don’t believe ocean warming affects them.
“People may think that climate change affecting the oceans is distant,” Cheung said, “but in fact it is affecting people in so many different ways.”
AI: No Silver Bullet ‘When it Comes to Climate Change’
Our world is running on artificial intelligence more and more with each passing day. But what does this mean for solving climate change? A team of experts in AI sought to find out.
In a new perspective paper in Nature Climate Change, the experts lay out a framework for understanding how AI and machine learning impact greenhouse gas emissions. They looked at three categories of impacts: those coming from the hardware and computational power itself, the immediate application of AI technologies and the systems-level societal changes that come from AI technologies.
“There are many ways in which AI is being used that are explicitly reducing greenhouse gas emissions,” said study author David Rolnick, a professor at McGill University in Montreal. “There are also ways that AI is being used in ways that actively contribute to climate change.”
Some benefits that AI provides for climate change, the authors write, include better tracking carbon emissions so companies and other institutions can measure greenhouse gases and find ways to reduce their impact. AI can also help improve energy efficiency, support development of clean energy industries and monitor climate change causes and effects like deforestation and coastal sea level rise.
Yet AI can also lead to increases in greenhouse gas emissions, accelerating climate change, the authors write. This includes the energy used to power computations and the extraction of resources to assemble the hardware used in computing. Beyond that, AI is being used to drive more personalized advertising, which Rolnick said could lead to increased consumption of material goods and more greenhouse gas emissions. Also, AI is powering the growth of autonomous vehicles, which Rolnick said could reinforce society’s reliance on personal vehicles rather than more climate-friendly public transportation. The technology can also be used to help increase fossil fuel production, like facilitating oil and gas exploration.
Rolnick contributed to a recent report that provides policymakers with recommendations for how to use AI as a climate solution, including investing in research, improving data access and incentivizing climate-friendly applications of AI.
Rolnick doesn’t believe that climate change will be solved by AI, but he said future machine learning technologies should be developed with climate change in mind for measuring emissions associated with them.
“I’m very optimistic about many applications of AI within the context of climate action, but I don’t think that it is the way to achieve climate action or solve climate change,” he said. “There are no silver bullets and certainly not a silver bullet when it comes to climate change.”
Vanuatu Gets an Olympic Skier—to Sound the Climate Alarm
Vanuatu has never sent an athlete to the Winter Olympics. But one of the Pacific island nation’s newest citizens hopes to change that in 2026, while also bringing attention to the country’s ticking climate clock.
Jeanee Crane-Mauzy is a professional halfpipe skier living in Park City, Utah, but recently obtained citizenship in Vanuatu, although due to Covid-19 travel restrictions, she’s never been in the country. She was able to secure citizenship through a program that awards citizenship in exchange for financial investment in the country.
Vanuatu is made up of about 80 low-lying islands a few thousand miles away from Australia’s eastern coast. In a warming climate, Vanuatu faces an onslaught of challenges, like intense tropical storms, sea level rise and acidifying oceans that degrade coastal fisheries. These climate threats lead the island’s residents to question how much longer they can continue to live in their own country, despite having contributed very little to the global climate problem.
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That’s what has driven Vanuatu’s leaders to seek an advisory opinion from the International Court of Justice, which could help the country hold others responsible for the damage inflicted on the islands by climate change. The effort has picked up support from other nations in recent months, and a decision could influence future decisions in national courts to hold polluters accountable for their greenhouse gas emissions.
Crane-Mauzy was inspired by the small country’s push to hold the rest of the world accountable for climate change. She wants to help elevate that push by representing Vanuatu in the Winter Olympics.
“The Olympics is the biggest venue for sports, so being able to represent them and actually go into the opening ceremonies and compete with their flag would really help the rest of the world learn about Vanuatu,” she said. Competing for the United States would be like being a small fish in a big pond, she said, while competing for Vanuatu would give her the platform to spread the country’s message of climate alarm.
Crane-Mauzy will continue to compete as an American for the next two years, she said, at which point the International Ski Federation will allow her to change her nationality and ski in Olympic qualifying competitions as a Vanuatu citizen.
She plans to visit Vanuatu for the first time in August to further connect with the country’s residents and learn more about how she can support their efforts.
“It’s definitely a very delicate point to be able to represent a country that I have not been born or raised in,” she said. “I want to be able to really spend time in Vanuatu and work on more of the messaging for the Olympic Games to make sure that I’m truly representing everybody there well.”