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    Puzzling out climate change

    Shreyaa Raghavan’s journey into solving some of the world’s toughest challenges started with a simple love for puzzles. By high school, her knack for problem-solving naturally drew her to computer science. Through her participation in an entrepreneurship and leadership program, she built apps and twice made it to the semifinals of the program’s global competition.Her early successes made a computer science career seem like an obvious choice, but Raghavan says a significant competing interest left her torn.“Computer science sparks that puzzle-, problem-solving part of my brain,” says Raghavan ’24, an Accenture Fellow and a PhD candidate in MIT’s Institute for Data, Systems, and Society. “But while I always felt like building mobile apps was a fun little hobby, it didn’t feel like I was directly solving societal challenges.”Her perspective shifted when, as an MIT undergraduate, Raghavan participated in an Undergraduate Research Opportunity in the Photovoltaic Research Laboratory, now known as the Accelerated Materials Laboratory for Sustainability. There, she discovered how computational techniques like machine learning could optimize materials for solar panels — a direct application of her skills toward mitigating climate change.“This lab had a very diverse group of people, some from a computer science background, some from a chemistry background, some who were hardcore engineers. All of them were communicating effectively and working toward one unified goal — building better renewable energy systems,” Raghavan says. “It opened my eyes to the fact that I could use very technical tools that I enjoy building and find fulfillment in that by helping solve major climate challenges.”With her sights set on applying machine learning and optimization to energy and climate, Raghavan joined Cathy Wu’s lab when she started her PhD in 2023. The lab focuses on building more sustainable transportation systems, a field that resonated with Raghavan due to its universal impact and its outsized role in climate change — transportation accounts for roughly 30 percent of greenhouse gas emissions.“If we were to throw all of the intelligent systems we are exploring into the transportation networks, by how much could we reduce emissions?” she asks, summarizing a core question of her research.Wu, an associate professor in the Department of Civil and Environmental Engineering, stresses the value of Raghavan’s work.“Transportation is a critical element of both the economy and climate change, so potential changes to transportation must be carefully studied,” Wu says. “Shreyaa’s research into smart congestion management is important because it takes a data-driven approach to add rigor to the broader research supporting sustainability.”Raghavan’s contributions have been recognized with the Accenture Fellowship, a cornerstone of the MIT-Accenture Convergence Initiative for Industry and Technology. As an Accenture Fellow, she is exploring the potential impact of technologies for avoiding stop-and-go traffic and its emissions, using systems such as networked autonomous vehicles and digital speed limits that vary according to traffic conditions — solutions that could advance decarbonization in the transportation section at relatively low cost and in the near term.Raghavan says she appreciates the Accenture Fellowship not only for the support it provides, but also because it demonstrates industry involvement in sustainable transportation solutions.“It’s important for the field of transportation, and also energy and climate as a whole, to synergize with all of the different stakeholders,” she says. “I think it’s important for industry to be involved in this issue of incorporating smarter transportation systems to decarbonize transportation.”Raghavan has also received a fellowship supporting her research from the U.S. Department of Transportation.“I think it’s really exciting that there’s interest from the policy side with the Department of Transportation and from the industry side with Accenture,” she says.Raghavan believes that addressing climate change requires collaboration across disciplines. “I think with climate change, no one industry or field is going to solve it on its own. It’s really got to be each field stepping up and trying to make a difference,” she says. “I don’t think there’s any silver-bullet solution to this problem. It’s going to take many different solutions from different people, different angles, different disciplines.”With that in mind, Raghavan has been very active in the MIT Energy and Climate Club since joining about three years ago, which, she says, “was a really cool way to meet lots of people who were working toward the same goal, the same climate goals, the same passions, but from completely different angles.”This year, Raghavan is on the community and education team, which works to build the community at MIT that is working on climate and energy issues. As part of that work, Raghavan is launching a mentorship program for undergraduates, pairing them with graduate students who help the undergrads develop ideas about how they can work on climate using their unique expertise.“I didn’t foresee myself using my computer science skills in energy and climate,” Raghavan says, “so I really want to give other students a clear pathway, or a clear sense of how they can get involved.”Raghavan has embraced her area of study even in terms of where she likes to think.“I love working on trains, on buses, on airplanes,” she says. “It’s really fun to be in transit and working on transportation problems.”Anticipating a trip to New York to visit a cousin, she holds no dread for the long train trip.“I know I’m going to do some of my best work during those hours,” she says. “Four hours there. Four hours back.” More

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    3 Questions: What the laws of physics tell us about CO2 removal

    Human activities continue to pump billions of tons of carbon dioxide into the atmosphere each year, raising global temperatures and driving extreme weather events. As countries grapple with climate impacts and ways to significantly reduce carbon emissions, there have been various efforts to advance carbon dioxide removal (CDR) technologies that directly remove carbon dioxide from the air and sequester it for long periods of time.Unlike carbon capture and storage technologies, which are designed to remove carbon dioxide at point sources such as fossil-fuel plants, CDR aims to remove carbon dioxide molecules that are already circulating in the atmosphere.A new report by the American Physical Society and led by an MIT physicist provides an overview of the major experimental CDR approaches and determines their fundamental physical limits. The report focuses on methods that have the biggest potential for removing carbon dioxide, at the scale of gigatons per year, which is the magnitude that would be required to have a climate-stabilizing impact.The new report was commissioned by the American Physical Society’s Panel on Public Affairs, and appeared last week in the journal PRX. The report was chaired by MIT professor of physics Washington Taylor, who spoke with MIT News about CDR’s physical limitations and why it’s worth pursuing in tandem with global efforts to reduce carbon emissions.Q: What motivated you to look at carbon dioxide removal systems from a physical science perspective?A: The number one thing driving climate change is the fact that we’re taking carbon that has been stuck in the ground for 100 million years, and putting it in the atmosphere, and that’s causing warming. In the last few years there’s been a lot of interest both by the government and private entities in finding technologies to directly remove the CO2 from the air.How to manage atmospheric carbon is the critical question in dealing with our impact on Earth’s climate. So, it’s very important for us to understand whether we can affect the carbon levels not just by changing our emissions profile but also by directly taking carbon out of the atmosphere. Physics has a lot to say about this because the possibilities are very strongly constrained by thermodynamics, mass issues, and things like that.Q: What carbon dioxide removal methods did you evaluate?A: They’re all at an early stage. It’s kind of the Wild West out there in terms of the different ways in which companies are proposing to remove carbon from the atmosphere. In this report, we break down CDR processes into two classes: cyclic and once-through.Imagine we are in a boat that has a hole in the hull and is rapidly taking on water. Of course, we want to plug the hole as quickly as we can. But even once we have fixed the hole, we need to get the water out so we aren’t in danger of sinking or getting swamped. And this is particularly urgent if we haven’t completely fixed the hole so we still have a slow leak. Now, imagine we have a couple of options for how to get the water out so we don’t sink.The first is a sponge that we can use to absorb water, that we can then squeeze out and reuse. That’s a cyclic process in the sense that we have some material that we’re using over and over. There are cyclic CDR processes like chemical “direct air capture” (DAC), which acts basically like a sponge. You set up a big system with fans that blow air past some material that captures carbon dioxide. When the material is saturated, you close off the system and then use energy to essentially squeeze out the carbon and store it in a deep repository. Then you can reuse the material, in a cyclic process.The second class of approaches is what we call “once-through.” In the boat analogy, it would be as if you try to fix the leak using cartons of paper towels. You let them saturate and then throw them overboard, and you use each roll once.There are once-through CDR approaches, like enhanced rock weathering, that are designed to accelerate a natural process, by which certain rocks, when exposed to air, will absorb carbon from the atmosphere. Worldwide, this natural rock weathering is estimated to remove about 1 gigaton of carbon each year. “Enhanced rock weathering” is a CDR approach where you would dig up a lot of this rock, grind it up really small, to less than the width of a human hair, to get the process to happen much faster. The idea is, you dig up something, spread it out, and absorb CO2 in one go.The key difference between these two processes is that the cyclic process is subject to the second law of thermodynamics and there’s an energy constraint. You can set an actual limit from physics, saying any cyclic process is going to take a certain amount of energy, and that cannot be avoided. For example, we find that for cyclic direct-air-capture (DAC) plants, based on second law limits, the absolute minimum amount of energy you would need to capture a gigaton of carbon is comparable to the total yearly electric energy consumption of the state of Virginia. Systems currently under development use at least three to 10 times this much energy on a per ton basis (and capture tens of thousands, not billions, of tons). Such systems also need to move a lot of air; the air that would need to pass through a DAC system to capture a gigaton of CO2 is comparable to the amount of air that passes through all the air cooling systems on the planet.On the other hand, if you have a once-through process, you could in some respects avoid the energy constraint, but now you’ve got a materials constraint due to the central laws of chemistry. For once-through processes like enhanced rock weathering, that means that if you want to capture a gigaton of CO2, roughly speaking, you’re going to need a billion tons of rock.So, to capture gigatons of carbon through engineered methods requires tremendous amounts of physical material, air movement, and energy. On the other hand, everything we’re doing to put that CO2 in the atmosphere is extensive too, so large-scale emissions reductions face comparable challenges.Q: What does the report conclude, in terms of whether and how to remove carbon dioxide from the atmosphere?A: Our initial prejudice was, CDR is just going to take so much energy, and there’s no way around that because of the second law of thermodynamics, regardless of the method.But as we discussed, there is this nuance about cyclic versus once-through systems. And there are two points of view that we ended up threading a needle between. One is the view that CDR is a silver bullet, and we’ll just do CDR and not worry about emissions — we’ll just suck it all out of the atmosphere. And that’s not the case. It will be really expensive, and will take a lot of energy and materials to do large-scale CDR. But there’s another view, where people say, don’t even think about CDR. Even thinking about CDR will compromise our efforts toward emissions reductions. The report comes down somewhere in the middle, saying that CDR is not a magic bullet, but also not a no-go.If we are serious about managing climate change, we will likely want substantial CDR in addition to aggressive emissions reductions. The report concludes that research and development on CDR methods should be selectively and prudently pursued despite the expected cost and energy and material requirements.At a policy level, the main message is that we need an economic and policy framework that incentivizes emissions reductions and CDR in a common framework; this would naturally allow the market to optimize climate solutions. Since in many cases it is much easier and cheaper to cut emissions than it will likely ever be to remove atmospheric carbon, clearly understanding the challenges of CDR should help motivate rapid emissions reductions.For me, I’m optimistic in the sense that scientifically we understand what it will take to reduce emissions and to use CDR to bring CO2 levels down to a slightly lower level. Now, it’s really a societal and economic problem. I think humanity has the potential to solve these problems. I hope that we can find common ground so that we can take actions as a society that will benefit both humanity and the broader ecosystems on the planet, before we end up having bigger problems than we already have.  More

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    Seeking climate connections among the oceans’ smallest organisms

    Andrew Babbin tries to pack light for work trips. Along with the travel essentials, though, he also brings a roll each of electrical tape, duct tape, lab tape, a pack of cable ties, and some bungee cords.“It’s my MacGyver kit: You never know when you have to rig something on the fly in the field or fix a broken bag,” Babbin says.The trips Babbin takes are far out to sea, on month-long cruises, where he works to sample waters off the Pacific coast and out in the open ocean. In remote locations, repair essentials often come in handy, as when Babbin had to zip-tie a wrench to a sampling device to help it sink through an icy Antarctic lake.Babbin is an oceanographer and marine biogeochemist who studies marine microbes and the ways in which they control the cycling of nitrogen between the ocean and the atmosphere. This exchange helps maintain healthy ocean ecosystems and supports the ocean’s capacity to store carbon.By combining measurements that he takes in the ocean with experiments in his MIT lab, Babbin is working to understand the connections between microbes and ocean nitrogen, which could in turn help scientists identify ways to maintain the ocean’s health and productivity. His work has taken him to many coastal and open-ocean regions around the globe.“You really become an oceanographer and an Earth scientist to see the world,” says Babbin, who recently earned tenure as the Cecil and Ida Green Career Development Professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “We embrace the diversity of places and cultures on this planet. To see just a small fraction of that is special.”A powerful cycleThe ocean has been a constant presence for Babbin since childhood. His family is from Monmouth County, New Jersey, where he and his twin sister grew up playing along the Jersey shore. When they were teenagers, their parents took the kids on family cruise vacations.“I always loved being on the water,” he says. “My favorite parts of any of those cruises were the days at sea, where you were just in the middle of some ocean basin with water all around you.”In school, Babbin gravitated to the sciences, and chemistry in particular. After high school, he attended Columbia University, where a visit to the school’s Earth and environmental engineering department catalyzed a realization.“For me, it was always this excitement about the water and about chemistry, and it was this pop of, ‘Oh wow, it doesn’t have to be one or the other,’” Babbin says.He chose to major in Earth and environmental engineering, with a concentration in water resources and climate risks. After graduating in 2008, Babbin returned to his home state, where he attended Princeton University and set a course for a PhD in geosciences, with a focus on chemical oceanography and environmental microbiology. His advisor, oceanographer Bess Ward, took Babbin on as a member of her research group and invited him on several month-long cruises to various parts of the eastern tropical Pacific.“I still remember that first trip,” Babbin recalls. “It was a whirlwind. Everyone else had been to sea a gazillion times and was loading the boat and strapping things down, and I had no idea of anything. And within a few hours, I was doing an experiment as the ship rocked back and forth!”Babbin learned to deploy sampling cannisters overboard, then haul them back up and analyze the seawater inside for signs of nitrogen — an essential nutrient for all living things on Earth.As it turns out, the plants and animals that depend on nitrogen to survive are unable to take it up from the atmosphere themselves. They require a sort of go-between, in the form of microbes that “fix” nitrogen, converting it from nitrogen gas to more digestible forms. In the ocean, this nitrogen fixation is done by highly specialized microbial species, which work to make nitrogen available to phytoplankton — microscopic plant-like organisms that are the foundation of the marine food chain. Phytoplankton are also a main route by which the ocean absorbs carbon dioxide from the atmosphere.Microorganisms may also use these biologically available forms of nitrogen for energy under certain conditions, returning nitrogen to the atmosphere. These microbes can also release a byproduct of nitrous oxide, which is a potent greenhouse gas that also can catalyze ozone loss in the stratosphere.Through his graduate work, at sea and in the lab, Babbin became fascinated with the cycling of nitrogen and the role that nitrogen-fixing microbes play in supporting the ocean’s ecosystems and the climate overall. A balance of nitrogen inputs and outputs sustains phytoplankton and maintains the ocean’s ability to soak up carbon dioxide.“Some of the really pressing questions in ocean biogeochemistry pertain to this cycling of nitrogen,” Babbin says. “Understanding the ways in which this one element cycles through the ocean, and how it is central to ecosystem health and the planet’s climate, has been really powerful.”In the lab and out to seaAfter completing his PhD in 2014, Babbin arrived at MIT as a postdoc in the Department of Civil and Environmental Engineering.“My first feeling when I came here was, wow, this really is a nerd’s playground,” Babbin says. “I embraced being part of a culture where we seek to understand the world better, while also doing the things we really want to do.”In 2017, he accepted a faculty position in MIT’s Department of Earth, Atmospheric and Planetary Sciences. He set up his laboratory space, painted in his favorite brilliant orange, on the top floor of the Green Building.His group uses 3D printers to fabricate microfluidic devices in which they reproduce the conditions of the ocean environment and study microbe metabolism and its effects on marine chemistry. In the field, Babbin has led research expeditions to the Galapagos Islands and parts of the eastern Pacific, where he has collected and analyzed samples of air and water for signs of nitrogen transformations and microbial activity. His new measuring station in the Galapagos is able to infer marine emissions of nitrous oxide across a large swath of the eastern tropical Pacific Ocean. His group has also sailed to southern Cuba, where the researchers studied interactions of microbes in coral reefs.Most recently, Babbin traveled to Antarctica, where he set up camp next to frozen lakes and plumbed for samples of pristine ice water that he will analyze for genetic remnants of ancient microbes. Such preserved bacterial DNA could help scientists understand how microbes evolved and influenced the Earth’s climate over billions of years.“Microbes are the terraformers,” Babbin notes. “They have been, since life evolved more than 3 billion years ago. We have to think about how they shape the natural world and how they will respond to the Anthropocene as humans monkey with the planet ourselves.”Collective actionBabbin is now charting new research directions. In addition to his work at sea and in the lab, he is venturing into engineering, with a new project to design denitrifying capsules. While nitrogen is an essential nutrient for maintaining a marine ecosystem, too much nitrogen, such as from fertilizer that runs off into lakes and streams, can generate blooms of toxic algae. Babbin is looking to design eco-friendly capsules that scrub excess anthropogenic nitrogen from local waterways. He’s also beginning the process of designing a new sensor to measure low-oxygen concentrations in the ocean. As the planet warms, the oceans are losing oxygen, creating “dead zones” where fish cannot survive. While others including Babbin have tried to map these oxygen minimum zones, or OMZs, they have done so sporadically, by dropping sensors into the ocean over limited range, depth, and times. Babbin’s sensors could potentially provide a more complete map of OMZs, as they would be deployed on wide-ranging, deep-diving, and naturally propulsive vehicles: sharks.“We want to measure oxygen. Sharks need oxygen. And if you look at where the sharks don’t go, you might have a sense of where the oxygen is not,” says Babbin, who is working with marine biologists on ways to tag sharks with oxygen sensors. “A number of these large pelagic fish move up and down the water column frequently, so you can map the depth to which they dive to, and infer something about the behavior. And my suggestion is, you might also infer something about the ocean’s chemistry.”When he reflects on what stimulates new ideas and research directions, Babbin credits working with others, in his own group and across MIT.“My best thoughts come from this collective action,” Babbin says. “Particularly because we all have different upbringings and approach things from a different perspective.”He’s bringing this collaborative spirit to his new role, as a mission director for MIT’s Climate Project. Along with Jesse Kroll, who is a professor of civil and environmental engineering and of chemical engineering, Babbin co-leads one of the project’s six missions: Restoring the Atmosphere, Protecting the Land and Oceans. Babbin and Kroll are planning a number of workshops across campus that they hope will generate new connections, and spark new ideas, particularly around ways to evaluate the effectiveness of different climate mitigation strategies and better assess the impacts of climate on society.“One area we want to promote is thinking of climate science and climate interventions as two sides of the same coin,” Babbin says. “There’s so much action that’s trying to be catalyzed. But we want it to be the best action. Because we really have one shot at doing this. Time is of the essence.” More

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    David McGee named head of the Department of Earth, Atmospheric and Planetary Sciences

    David McGee, the William R. Kenan Jr. Professor of Earth and Planetary Sciences at MIT, was recently appointed head of the MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS), effective Jan. 15. He assumes the role from Professor Robert van der Hilst, the Schlumberger Professor of Earth and Planetary Sciences, who led the department for 13 years.McGee specializes in applying isotope geochemistry and geochronology to reconstruct Earth’s climate history, helping to ground-truth our understanding of how the climate system responds during periods of rapid change. He has also been instrumental in the growth of the department’s community and culture, having served as EAPS associate department head since 2020.“David is an amazing researcher who brings crucial, data-based insights to aid our response to climate change,” says dean of the School of Science and the Curtis (1963) and Kathleen Marble Professor of Astrophysics Nergis Mavalvala. “He is also a committed and caring educator, providing extraordinary investment in his students’ learning experiences, and through his direction of Terrascope, one of our unique first-year learning communities focused on generating solutions to sustainability challenges.”   “I am energized by the incredible EAPS community, by Rob’s leadership over the last 13 years, and by President Kornbluth’s call for MIT to innovate effective and wise responses to climate change,” says McGee. “EAPS has a unique role in this time of reckoning with planetary boundaries — our collective path forward needs to be guided by a deep understanding of the Earth system and a clear sense of our place in the universe.”McGee’s research seeks to understand the Earth system’s response to past climate changes. Using geochemical analysis and uranium-series dating, McGee and his group investigate stalagmites, ancient lake deposits, and deep-sea sediments from field sites around the world to trace patterns of wind and precipitation, water availability in drylands, and permafrost stability through space and time. Armed with precise chronologies, he aims to shed light on drivers of historical hydroclimatic shifts and provide quantitative tests of climate model performance.Beyond research, McGee has helped shape numerous Institute initiatives focused on environment, climate, and sustainability, including serving on the MIT Climate and Sustainability Consortium Faculty Steering Committee and the faculty advisory board for the MIT Environment and Sustainability Minor.McGee also co-chaired MIT’s Climate Education Working Group, one of three working groups established under the Institute’s Fast Forward climate action plan. The group identified opportunities to strengthen climate- and sustainability-related education at the Institute, from curricular offerings to experiential learning opportunities and beyond.In April 2023, the working group hosted the MIT Symposium for Advancing Climate Education, featuring talks by McGee and others on how colleges and universities can innovate and help students develop the skills, capacities, and perspectives they’ll need to live, lead, and thrive in a world being remade by the accelerating climate crisis.“David is reimagining MIT undergraduate education to include meaningful collaborations with communities outside of MIT, teaching students that scientific discovery is important, but not always enough to make impact for society,” says van der Hilst. “He will help shape the future of the department with this vital perspective.”From the start of his career, McGee has been dedicated to sharing his love of exploration with students. He earned a master’s degree in teaching and spent seven years as a teacher in middle school and high school classrooms before earning his PhD in Earth and environmental sciences from Columbia University. He joined the MIT faculty in 2012, and in 2018 received the Excellence in Mentoring Award from MIT’s Undergraduate Advising and Academic Programming office. In 2015, he became the director of MIT’s Terrascope first-year learning community.“David’s exemplary teaching in Terrascope comes through his understanding that effective solutions must be found where science intersects with community engagement to forge ethical paths forward,” adds van der Hilst. In 2023, for his work with Terrascope, McGee received the school’s highest award, the School of Science Teaching Prize. In 2022, he was named a Margaret MacVicar Faculty Fellow, the highest teaching honor at MIT.As associate department head, McGee worked alongside van der Hilst and student leaders to promote EAPS community engagement, improve internal supports and reporting structures, and bolster opportunities for students to pursue advanced degrees and STEM careers. More

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    Smart carbon dioxide removal yields economic and environmental benefits

    Last year the Earth exceeded 1.5 degrees Celsius of warming above preindustrial times, a threshold beyond which wildfires, droughts, floods, and other climate impacts are expected to escalate in frequency, intensity, and lethality. To cap global warming at 1.5 C and avert that scenario, the nearly 200 signatory nations of the Paris Agreement on climate change will need to not only dramatically lower their greenhouse gas emissions, but also take measures to remove carbon dioxide (CO2) from the atmosphere and durably store it at or below the Earth’s surface.Past analyses of the climate mitigation potential, costs, benefits, and drawbacks of different carbon dioxide removal (CDR) options have focused primarily on three strategies: bioenergy with carbon capture and storage (BECCS), in which CO2-absorbing plant matter is converted into fuels or directly burned to generate energy, with some of the plant’s carbon content captured and then stored safely and permanently; afforestation/reforestation, in which CO2-absorbing trees are planted in large numbers; and direct air carbon capture and storage (DACCS), a technology that captures and separates CO2 directly from ambient air, and injects it into geological reservoirs or incorporates it into durable products. To provide a more comprehensive and actionable analysis of CDR, a new study by researchers at the MIT Center for Sustainability Science and Strategy (CS3) first expands the option set to include biochar (charcoal produced from plant matter and stored in soil) and enhanced weathering (EW) (spreading finely ground rock particles on land to accelerate storage of CO2 in soil and water). The study then evaluates portfolios of all five options — in isolation and in combination — to assess their capability to meet the 1.5 C goal, and their potential impacts on land, energy, and policy costs.The study appears in the journal Environmental Research Letters. Aided by their global multi-region, multi-sector Economic Projection and Policy Analysis (EPPA) model, the MIT CS3 researchers produce three key findings.First, the most cost-effective, low-impact strategy that policymakers can take to achieve global net-zero emissions — an essential step in meeting the 1.5 C goal — is to diversify their CDR portfolio, rather than rely on any single option. This approach minimizes overall cropland and energy consumption, and negative impacts such as increased food insecurity and decreased energy supplies.By diversifying across multiple CDR options, the highest CDR deployment of around 31.5 gigatons of CO2 per year is achieved in 2100, while also proving the most cost-effective net-zero strategy. The study identifies BECCS and biochar as most cost-competitive in removing CO2 from the atmosphere, followed by EW, with DACCS as uncompetitive due to high capital and energy requirements. While posing logistical and other challenges, biochar and EW have the potential to improve soil quality and productivity across 45 percent of all croplands by 2100.“Diversifying CDR portfolios is the most cost-effective net-zero strategy because it avoids relying on a single CDR option, thereby reducing and redistributing negative impacts on agriculture, forestry, and other land uses, as well as on the energy sector,” says Solene Chiquier, lead author of the study who was a CS3 postdoc during its preparation.The second finding: There is no optimal CDR portfolio that will work well at global and national levels. The ideal CDR portfolio for a particular region will depend on local technological, economic, and geophysical conditions. For example, afforestation and reforestation would be of great benefit in places like Brazil, Latin America, and Africa, by not only sequestering carbon in more acreage of protected forest but also helping to preserve planetary well-being and human health.“In designing a sustainable, cost-effective CDR portfolio, it is important to account for regional availability of agricultural, energy, and carbon-storage resources,” says Sergey Paltsev, CS3 deputy director, MIT Energy Initiative senior research scientist, and supervising co-author of the study. “Our study highlights the need for enhancing knowledge about local conditions that favor some CDR options over others.”Finally, the MIT CS3 researchers show that delaying large-scale deployment of CDR portfolios could be very costly, leading to considerably higher carbon prices across the globe — a development sure to deter the climate mitigation efforts needed to achieve the 1.5 C goal. They recommend near-term implementation of policy and financial incentives to help fast-track those efforts. More

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    MIT Climate and Energy Ventures class spins out entrepreneurs — and successful companies

    In 2014, a team of MIT students in course 15.366 (Climate and Energy Ventures) developed a plan to commercialize MIT research on how to move information between chips with light instead of electricity, reducing energy usage.After completing the class, which challenges students to identify early customers and pitch their business plan to investors, the team went on to win both grand prizes at the MIT Clean Energy Prize. Today the company, Ayar Labs, has raised a total of $370 million from a group including chip leaders AMD, Intel, and NVIDIA, to scale the manufacturing of its optical chip interconnects.Ayar Labs is one of many companies whose roots can be traced back to 15.366. In fact, more than 150 companies have been founded by alumni of the class since its founding in 2007.In the class, student teams select a technology or idea and determine the best path for its commercialization. The semester-long project, which is accompanied by lectures and mentoring, equips students with real-world experience in launching a business.“The goal is to educate entrepreneurs on how to start companies in the climate and energy space,” says Senior Lecturer Tod Hynes, who co-founded the course and has been teaching since 2008. “We do that through hands-on experience. We require students to engage with customers, talk to potential suppliers, partners, investors, and to practice their pitches to learn from that feedback.”The class attracts hundreds of student applications each year. As one of the catalysts for MIT spinoffs, it is also one reason a 2015 report found that MIT alumni-founded companies had generated roughly $1.9 trillion in annual revenues. If MIT were a country, that figure that would make it the 10th largest economy in the world, according to the report.“’Mens et manus’ (‘mind and hand’) is MIT’s motto, and the hands-on experience we try to provide in this class is hard to beat,” Hynes says. “When you actually go through the process of commercialization in the real world, you learn more and you’re in a better spot. That experiential learning approach really aligns with MIT’s approach.”Simulating a startupThe course was started by Bill Aulet, a professor of the practice at the MIT Sloan School of Management and the managing director of the Martin Trust Center for MIT Entrepreneurship. After serving as an advisor the first year and helping Aulet launch the class, Hynes began teaching the class with Aulet in the fall of 2008. The pair also launched the Climate and Energy Prize around the same time, which continues today and recently received over 150 applications from teams from around the world.A core feature of the class is connecting students in different academic fields. Each year, organizers aim to enroll students with backgrounds in science, engineering, business, and policy.“The class is meant to be accessible to anybody at MIT,” Hynes says, noting the course has also since opened to students from Harvard University. “We’re trying to pull across disciplines.”The class quickly grew in popularity around campus. Over the last few years, the course has had about 150 students apply for 50 spots.“I mentioned Climate and Energy Ventures in my application to MIT,” says Chris Johnson, a second-year graduate student in the Leaders for Global Operations (LGO) Program. “Coming into MIT, I was very interested in sustainability, and energy in particular, and also in startups. I had heard great things about the class, and I waited until my last semester to apply.”The course’s organizers select mostly graduate students, whom they prefer to be in the final year of their program so they can more easily continue working on the venture after the class is finished.“Whether or not students stick with the project from the class, it’s a great experience that will serve them in their careers,” says Jennifer Turliuk, the practice leader for climate and energy artificial intelligence at the Martin Trust Center for Entrepreneurship, who helped teach the class this fall.Hynes describes the course as a venture-building simulation. Before it begins, organizers select up to 30 technologies and ideas that are in the right stage for commercialization. Students can also come into the class with ideas or technologies they want to work on.After a few weeks of introductions and lectures, students form into multidisciplinary teams of about five and begin going through each of the 24 steps of building a startup described in Aulet’s book “Disciplined Entrepreneurship,” which includes things like engaging with potential early customers, quantifying a value proposition, and establishing a business model. Everything builds toward a one-hour final presentation that’s designed to simulate a pitch to investors or government officials.“It’s a lot of work, and because it’s a team-based project, your grade is highly dependent on your team,” Hynes says. “You also get graded by your team; that’s about 10 percent of your grade. We try to encourage people to be proactive and supportive teammates.”Students say the process is fast-paced but rewarding.“It’s definitely demanding,” says Sofie Netteberg, a graduate student who is also in the LGO program at MIT. “Depending on where you’re at with your technology, you can be moving very quickly. That’s the stage that I was in, which I found really engaging. We basically just had a lab technology, and it was like, ‘What do we do next?’ You also get a ton of support from the professors.”From the classroom to the worldThis fall’s final presentations took place at the headquarters of the MIT-affiliated venture firm The Engine in front of an audience of professors, investors, members of foundations supporting entrepreneurship, and more.“We got to hear feedback from people who would be the real next step for the technology if the startup gets up and running,” said Johnson, whose team was commercializing a method for storing energy in concrete. “That was really valuable. We know that these are not only people we might see in the next month or the next funding rounds, but they’re also exactly the type of people that are going to give us the questions we should be thinking about. It was clarifying.”Throughout the semester, students treated the project like a real venture they’d be working on well beyond the length of the class.“No one’s really thinking about this class for the grade; it’s about the learning,” says Netteberg, whose team was encouraged to keep working on their electrolyzer technology designed to more efficiently produce green hydrogen. “We’re not stressed about getting an A. If we want to keep working on this, we want real feedback: What do you think we did well? What do we need to keep working on?”Hynes says several investors expressed interest in supporting the businesses coming out of the class. Moving forward, he hopes students embrace the test-bed environment his team has created for them and try bold new things.“People have been very pragmatic over the years, which is good, but also potentially limiting,” Hynes says. “This is also an opportunity to do something that’s a little further out there — something that has really big potential impact if it comes together. This is the time where students get to experiment, so why not try something big?” More

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    Building resiliency

    Several years ago, the residents of a manufactured-home neighborhood in southeast suburban Houston, not far from the Buffalo Bayou, took a major step in dealing with climate problems: They bought the land under their homes. Then they installed better drainage and developed strategies to share expertise and tools for home repairs. The result? The neighborhood made it through Hurricane Harvey in 2017 and a winter freeze in 2021 without major damage.The neighborhood is part of a U.S. movement toward the Resident Owned Community (ROC) model for manufactured home parks. Many people in manufactured homes — mobile homes — do not own the land under them. But if the residents of a manufactured-home park can form an ROC, they can take action to adapt to climate risks — and ease the threat of eviction. With an ROC, manufactured-home residents can be there to stay.That speaks to a larger issue: In cities, lower-income residents are often especially vulnerable to natural hazards, such as flooding, extreme heat, and wildfire. But efforts aimed at helping cities as a whole withstand these disasters can lead to interventions that displace already-disadvantaged residents — by turning a low-lying neighborhood into a storm buffer, for instance.“The global climate crisis has very differential effects on cities, and neighborhoods within cities,” says Lawrence Vale, a professor of urban studies at MIT and co-author of a new book on the subject, “The Equitably Resilient City,” published by the MIT Press and co-authored with Zachary B. Lamb PhD ’18, an assistant professor at the University of California at Berkeley.In the book, the scholars delve into 12 case studies from around the globe which, they believe, have it both ways: Low- and middle-income communities have driven climate progress through tangible built projects, while also keeping people from being displaced, and indeed helping them participate in local governance and neighborhood decision-making.“We can either dive into despair about climate issues, or think they’re solvable and ask what it takes to succeed in a more equitable way,” says Vale, who is the Ford Professor of Urban Design and Planning at MIT. “This book is asking how people look at problems more holistically — to show how environmental impacts are integrated with their livelihoods, with feeling they can have security from displacement, and feeling they’re not going to be displaced, with being empowered to share in the governance where they live.”As Lamb notes, “Pursuing equitable urban climate adaptation requires both changes in the physical built environment of cities and innovations in institutions and governance practices to address deep-seated causes of inequality.”Twelve projects, four elementsResearch for “The Equitably Resilient City” began with exploration of about 200 potential cases, and ultimately focused on 12 projects from around the globe, including the U.S., Brazil, Thailand, and France. Vale and Lamb, coordinating with locally-based research teams, visited these diverse sites and conducted interviews in nine languages.All 12 projects work on multiple levels at once: They are steps toward environmental progress that also help local communities in civic and economic terms. The book uses the acronym LEGS (“livelihood, environment, governance, and security”) to encapsulate this need to make equitable progress on four different fronts.“Doing one of those things well is worth recognition, and doing all of them well is exciting,” Vale says. “It’s important to understand not just what these communities did, but how they did it and whose views were involved. These 12 cases are not a random sample. The book looks for people who are partially succeeding at difficult things in difficult circumstances.”One case study is set in São Paolo, Brazil, where low-income residents of a hilly favela benefitted from new housing in the area on undeveloped land that is less prone to slides. In San Juan, Puerto Rico, residents of low-lying neighborhoods abutting a water channel formed a durable set of community groups to create a fairer solution to flooding: Although the channel needed to be re-widened, the local coalition insisted on limiting displacement, supporting local livelihoods and improving environmental conditions and public space.“There is a backlash to older practices,” Vale says, referring to the large-scale urban planning and infrastructure projects of the mid-20th century, which often ignored community input. “People saw what happened during the urban renewal era and said, ‘You’re not going to do that to us again.’”Indeed, one through-line in “The Equitably Resilient City” is that cities, like all places, can be contested political terrain. Often, solid solutions emerge when local groups organize, advocate for new solutions, and eventually gain enough traction to enact them.“Every one of our examples and cases has probably 15 or 20 years of activity behind it, as well as engagements with a much deeper history,” Vale says. “They’re all rooted in a very often troubled [political] context. And yet these are places that have made progress possible.”Think locally, adapt anywhereAnother motif of “The Equitably Resilient City” is that local progress matters greatly, for a few reasons — including the value of having communities develop projects that meet their own needs, based on their input. Vale and Lamb are interested in projects even if they are very small-scale, and devote one chapter of the book to the Paris OASIS program, which has developed a series of cleverly designed, heavily tree-dotted school playgrounds across Paris. These projects provide environmental education opportunities and help mitigate flooding and urban heat while adding CO2-harnessing greenery to the cityscape.An individual park, by itself, can only do so much, but the concept behind it can be adopted by anyone.“This book is mostly centered on local projects rather than national schemes,” Vale says. “The hope is they serve as an inspiration for people to adapt to their own situations.”After all, the urban geography and governance of places such as Paris or São Paulo will differ widely. But efforts to make improvements to public open space or to well-located inexpensive housing stock applies in cities across the world.Similarly, the authors devote a chapter to work in the Cully neighborhood in Portland, Oregon, where community leaders have instituted a raft of urban environmental improvements while creating and preserving more affordable housing. The idea in the Cully area, as in all these cases, is to make places more resistant to climate change while enhancing them as good places to live for those already there.“Climate adaptation is going to mobilize enormous public and private resources to reshape cities across the globe,” Lamb notes. “These cases suggest pathways where those resources can make cities both more resilient in the face of climate change and more equitable. In fact, these projects show how making cities more equitable can be part of making them more resilient.”Other scholars have praised the book. Eric Klinenberg, director of New York University’s Institute for Public Knowledge has called it “at once scholarly, constructive, and uplifting, a reminder that better, more just cities remain within our reach.”Vale also teaches some of the book’s concepts in his classes, finding that MIT students, wherever they are from, enjoy the idea of thinking creatively about climate resilience.“At MIT, students want to find ways of applying technical skills to urgent global challenges,” Vale says. “I do think there are many opportunities, especially at a time of climate crisis. We try to highlight some of the solutions that are out there. Give us an opportunity, and we’ll show you what a place can be.” More

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    Toward sustainable decarbonization of aviation in Latin America

    According to the International Energy Agency, aviation accounts for about 2 percent of global carbon dioxide emissions, and aviation emissions are expected to double by mid-century as demand for domestic and international air travel rises. To sharply reduce emissions in alignment with the Paris Agreement’s long-term goal to keep global warming below 1.5 degrees Celsius, the International Air Transport Association (IATA) has set a goal to achieve net-zero carbon emissions by 2050. Which raises the question: Are there technologically feasible and economically viable strategies to reach that goal within the next 25 years?To begin to address that question, a team of researchers at the MIT Center for Sustainability Science and Strategy (CS3) and the MIT Laboratory for Aviation and the Environment has spent the past year analyzing aviation decarbonization options in Latin America, where air travel is expected to more than triple by 2050 and thereby double today’s aviation-related emissions in the region.Chief among those options is the development and deployment of sustainable aviation fuel. Currently produced from low- and zero-carbon sources (feedstock) including municipal waste and non-food crops, and requiring practically no alteration of aircraft systems or refueling infrastructure, sustainable aviation fuel (SAF) has the potential to perform just as well as petroleum-based jet fuel with as low as 20 percent of its carbon footprint.Focused on Brazil, Chile, Colombia, Ecuador, Mexico and Peru, the researchers assessed SAF feedstock availability, the costs of corresponding SAF pathways, and how SAF deployment would likely impact fuel use, prices, emissions, and aviation demand in each country. They also explored how efficiency improvements and market-based mechanisms could help the region to reach decarbonization targets. The team’s findings appear in a CS3 Special Report.SAF emissions, costs, and sourcesUnder an ambitious emissions mitigation scenario designed to cap global warming at 1.5 C and raise the rate of SAF use in Latin America to 65 percent by 2050, the researchers projected aviation emissions to be reduced by about 60 percent in 2050 compared to a scenario in which existing climate policies are not strengthened. To achieve net-zero emissions by 2050, other measures would be required, such as improvements in operational and air traffic efficiencies, airplane fleet renewal, alternative forms of propulsion, and carbon offsets and removals.As of 2024, jet fuel prices in Latin America are around $0.70 per liter. Based on the current availability of feedstocks, the researchers projected SAF costs within the six countries studied to range from $1.11 to $2.86 per liter. They cautioned that increased fuel prices could affect operating costs of the aviation sector and overall aviation demand unless strategies to manage price increases are implemented.Under the 1.5 C scenario, the total cumulative capital investments required to build new SAF producing plants between 2025 and 2050 were estimated at $204 billion for the six countries (ranging from $5 billion in Ecuador to $84 billion in Brazil). The researchers identified sugarcane- and corn-based ethanol-to-jet fuel, palm oil- and soybean-based hydro-processed esters and fatty acids as the most promising feedstock sources in the near term for SAF production in Latin America.“Our findings show that SAF offers a significant decarbonization pathway, which must be combined with an economy-wide emissions mitigation policy that uses market-based mechanisms to offset the remaining emissions,” says Sergey Paltsev, lead author of the report, MIT CS3 deputy director, and senior research scientist at the MIT Energy Initiative.RecommendationsThe researchers concluded the report with recommendations for national policymakers and aviation industry leaders in Latin America.They stressed that government policy and regulatory mechanisms will be needed to create sufficient conditions to attract SAF investments in the region and make SAF commercially viable as the aviation industry decarbonizes operations. Without appropriate policy frameworks, SAF requirements will affect the cost of air travel. For fuel producers, stable, long-term-oriented policies and regulations will be needed to create robust supply chains, build demand for establishing economies of scale, and develop innovative pathways for producing SAF.Finally, the research team recommended a region-wide collaboration in designing SAF policies. A unified decarbonization strategy among all countries in the region will help ensure competitiveness, economies of scale, and achievement of long-term carbon emissions-reduction goals.“Regional feedstock availability and costs make Latin America a potential major player in SAF production,” says Angelo Gurgel, a principal research scientist at MIT CS3 and co-author of the study. “SAF requirements, combined with government support mechanisms, will ensure sustainable decarbonization while enhancing the region’s connectivity and the ability of disadvantaged communities to access air transport.”Financial support for this study was provided by LATAM Airlines and Airbus. More