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      in Environment

      Advancing material innovation to address the polymer waste crisis

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      Products made from polymers — ranging from plastic bags to clothing to cookware to electronics — provide many comforts and support today’s standard of living, but since they do not decompose easily, they pose long-term environmental challenges. Developing polymers, a large class of materials, with a more sustainable life cycle is a critical step in making progress toward a green economy and addressing this piece of the global climate change crisis. The development of biodegradable polymers, however, remains limited by current biodegradation testing methods.

      To address this limitation, a team of MIT researchers led by Bradley D. Olsen, the Alexander and I. Michael Kasser (1960) Professor in the Department of Chemical Engineering, has developed an expansive biodegradation dataset to help determine whether or not a polymer is biodegradable.

      Their findings were recently published in The Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS), in a paper titled “High-Throughput Experimentation for Discovery of Biodegradable Polyesters.” The MIT team is led by Olsen and PhD candidates Katharina A. Fransen and Sarah H. M. Av-Ron, and also includes postdoc Dylan J. Walsh and undergraduate students Tess R. Buchanan, Dechen T. Rota, and Lana Van Note.

      “Despite polymer waste being a known and significant contributor to the climate crisis, the study of polymer biodegradation has been limited to a small number of polymers because current biodegradation testing methods are time- and resource-intensive,” says Olsen. “This limited scope slows new material innovation, so we are working to open that up to a much broader portfolio of materials.”

      Unique high-throughput approach

      The dataset Olsen’s team has developed, with support from the MIT Climate and Sustainability Consortium (MCSC), the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), and DIC Corporation, includes more than 600 distinct polyester chemistries.

      “The ingenuity of our work is pushing the screening to be high-throughput, which accelerates the pace of discovery,” says Av-Ron. High-throughput synthesis methods enable large quantities of samples to be screened rapidly, identifying products with the desired property or function you are looking for. In this case, the high-throughput approach was conducted using a method called clear-zone assay, which detects polymer biofragmentation and identifies polymer degrading bacteria. The biodegradation dataset can then lead to structure-property relationships, a concept central to materials science and engineering, where relationships between the chemical detail and property can be established, and used to build a biodegradation prediction model. When developing these models to predict biodegradation, the researchers were interested in looking into the potential linearity and nonlinearity of the relationships between structure and biodegradability.

      “We consider our scientific breakthrough to be having this large dataset, and the qualitative relationships and predictive models such a substantial  amount of data enabled,” adds Av-Ron. “It was captivating to figure out how to integrate the high complexity of polymer chemical representation with predictive machine-learning models. I was very excited to get a validation accuracy of 82 percent for one representation/model combination. With additional data we might be able to improve our predictions even more.”

      The team’s work focuses largely on polyesters; the development of biodegradable polyesters presents a key opportunity for addressing the polymer sustainability crisis and reducing the environmental burden of the polymer life cycle.

      One strain of bacteria, many chemistries

      The biodegradation test that these data create is accessible and cost-effective to put in place; initial industry feedback has been positive. The datasets are also more reproducible than many other standards in this space.

      “With our method, there is one strain of bacteria, so you know exactly what you’re testing,” says Av-Ron. This speaks to the uniqueness of the team’s approach.

      “When polymers are developed, normally the strength of the material is examined first, and then once the material is developed, whether or not it biodegrades comes second,” says Fransen.

      Olsen and his team are examining the opposite — developing the biodegradability screen first, to help filter and focus what to look for in a material. This way, the team’s infrastructure can assess a lot of different options, quickly.

      “There has been big movement recently in developing sustainable polymers,” concludes Fransen, “and having something like this that is quick, tangible, and relatively inexpensive, could add a lot of value to that community.”

      Fransen received a 2022 J-WAFS Fellowship for this work, and she and Av-Ron together won second place in the 2022 J-WAFS World Food Day Student Video Competition, as this research can be applied to creating more sustainable food packaging. More

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      Q&A: Are far-reaching fires the new normal?

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      Where there’s smoke, there is fire. But with climate change, larger and longer-burning wildfires are sending smoke farther from their source, often to places that are unaccustomed to the exposure. That’s been the case this week, as smoke continues to drift south from massive wildfires in Canada, prompting warnings of hazardous air quality, and poor visibility in states across New England, the mid-Atlantic, and the Midwest.

      As wildfire season is just getting going, many may be wondering: Are the air-polluting effects of wildfires a new normal?

      MIT News spoke with Professor Colette Heald of the Department of Civil and Environmental Engineering and the Department of Earth, Atmospheric and Planetary Sciences, and Professor Noelle Selin of the Institute for Data, Systems and Society and the Department of Earth, Atmospheric and Planetary Sciences. Heald specializes in atmospheric chemistry and has studied the climate and health effects associated with recent wildfires, while Selin works with atmospheric models to track air pollutants around the world, which she uses to inform policy decisions on mitigating  pollution and climate change. The researchers shared some of their insights on the immediate impacts of Canada’s current wildfires and what downwind regions may expect in the coming months, as the wildfire season stretches into summer.  

      Q: What role has climate change and human activity played in the wildfires we’ve seen so far this year?

      Heald: Unusually warm and dry conditions have dramatically increased fire susceptibility in Canada this year. Human-induced climate change makes such dry and warm conditions more likely. Smoke from fires in Alberta and Nova Scotia in May, and Quebec in early June, has led to some of the worst air quality conditions measured locally in Canada. This same smoke has been transported into the United States and degraded air quality here as well. Local officials have determined that ignitions have been associated with lightning strikes, but human activity has also played a role igniting some of the fires in Alberta.

      Q: What can we expect for the coming months in terms of the pattern of wildfires and their associated air pollution across the United States?

      Heald: The Government of Canada is projecting higher-than-normal fire activity throughout the 2023 fire season. Fire susceptibility will continue to respond to changing weather conditions, and whether the U.S. is impacted will depend on the winds and how air is transported across those regions. So far, the fire season in the United States has been below average, but fire risk is expected to increase modestly through the summer, so we may see local smoke influences as well.

      Q: How has air pollution from wildfires affected human health in the U.S. this year so far?

      Selin: The pollutant of most concern in wildfire smoke is fine particulate matter (PM2.5) – fine particles in the atmosphere that can be inhaled deep into the lungs, causing health damages. Exposure to PM2.5 causes respiratory and cardiovascular damage, including heart attacks and premature deaths. It can also cause symptoms like coughing and difficulty breathing. In New England this week, people have been breathing much higher concentrations of PM2.5 than usual. People who are particularly vulnerable to the effects are likely experiencing more severe impacts, such as older people and people with underlying conditions. But PM2.5 affects everyone. While the number and impact of wildfires varies from year to year, the associated air pollution from them generally lead to tens of thousands of premature deaths in the U.S. overall annually. There is also some evidence that PM2.5 from fires could be particularly damaging to health.

      While we in New England usually have relatively lower levels of pollution, it’s important also to note that some cities around the globe experience very high PM2.5 on a regular basis, not only from wildfires, but other sources such as power plants and industry. So, while we’re feeling the effects over the past few days, we should remember the broader importance of reducing PM2.5 levels overall for human health everywhere.

      Q: While firefighters battle fires directly this wildfire season, what can we do to reduce the effects of associated air pollution? And what can we do in the long-term, to prevent or reduce wildfire impacts?

      Selin: In the short term, protecting yourself from the impacts of PM2.5 is important. Limiting time outdoors, avoiding outdoor exercise, and wearing a high-quality mask are some strategies that can minimize exposure. Air filters can help reduce the concentrations of particles in indoor air. Taking measures to avoid exposure is particularly important for vulnerable groups. It’s also important to note that these strategies aren’t equally possible for everyone (for example, people who work outside) — stressing the importance of developing new strategies to address the underlying causes of increasing wildfires.

      Over the long term, mitigating climate change is important — because warm and dry conditions lead to wildfires, warming increases fire risk. Preventing the fires that are ignited by people or human activities can help.  Another way that damages can be mitigated in the longer term is by exploring land management strategies that could help manage fire intensity. More

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      in Environment

      Q&A: Gabriela Sá Pessoa on Brazilian politics, human rights in the Amazon, and AI

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      Gabriela Sá Pessoa is a journalist passionate about the intersection of human rights and climate change. She came to MIT from The Washington Post, where she worked from her home country of Brazil as a news researcher reporting on the Amazon, human rights violations, and environmental crimes. Before that, she held roles at two of the most influential media outlets in Brazil: Folha de S.Paulo, covering local and national politics, and UOL, where she was assigned to coronavirus coverage and later joined the investigative desk.

      Sá Pessoa was awarded the 2023 Elizabeth Neuffer Fellowship by the International Women’s Media Foundation, which supports its recipient with research opportunities at MIT and further training at The Boston Globe and The New York Times. She is currently based at the MIT Center for International Studies. Recently, she sat down to talk about her work on the Amazon, recent changes in Brazilian politics, and her experience at MIT.

      Q: One focus of your reporting is human rights and environmental issues in the Amazon. As part of your fellowship, you contributed to a recent editorial in The Boston Globe on fighting deforestation in the region. Why is reporting on this topic important?

      A: For many Brazilians, the Amazon is a remote and distant territory, and people living in other parts of the country aren’t fully aware of all of its problems and all of its potential. This is similar to the United States — like many people here, they don’t see how they could be related to the human rights violations and the destruction of the rainforest that are happening.

      But, we are all complicit in the destruction in some ways because the economic forces driving the deforestation of the rainforest all have a market, and these markets are everywhere, in Brazil and here in the U.S. I think it is part of journalism to show people in the U.S., Brazil, and elsewhere that we are part of the problem, and as part of the problem, we should be part of the solution by being aware of it, caring about it, and taking actions that are within our power.

      In the U.S., for example, voters can influence policy like the current negotiations for financial support for fighting deforestation in the Amazon. And as consumers, we can be more aware — is the beef we are consuming related to deforestation? Is the timber on our construction sites coming from the Amazon?

      Truth is, in Brazil, we have turned our backs to the Amazon for so long. It’s our duty to protect it for the sake of climate change. If we don’t take care of it, there will be serious consequences to our local climate, our local communities, and for the whole world. It’s a huge matter of human rights because our living depends on that, both locally and globally.

      Q: Before coming to MIT, you were at The Washington Post in São Paulo, where you contributed to reporting on the recent presidential election. What changes do you expect to see with the new Lula administration?

      A: To climate and environment, the first signs were positive. But the optimism did not last a semester, as politics is imposing itself. Lula is facing increasing difficulty building a majority in a conservative Congress, over which agribusiness holds tremendous power and influence. As we speak, environmental policy is under Congress’s attack. A committee in the House has just passed a ruling drowning power from the environmental minister, Marina Silva, and from the recently created National Indigenous People Ministry, led by Sonia Guajajara. Both Marina and Sonia are global ecological and human rights champions, and I wonder what the impact would be if Congress ratifies these changes. It is still unclear how it would impact the efforts to fight deforestation.

      In addition, there is an internal dispute in the government between environmentalists and those in favor of mining and big infrastructure projects. Petrobras, the state-run oil company, is trying to get authorization to research and drill offshore oil reserves in the mouth of the Amazon River. The federal environmental protection agency did a conclusive report suspending the operation, saying it is critical and threatens the region’s sensitive environment and indigenous communities. And, of course, it would be another source of greenhouse gas emissions. ​

      That said, it’s not a denialist government. I should mention the quick response from the administration to the Yanomami genocide earlier this year. In January, an independent media organization named Sumaúma reported on the deaths of over five hundred indigenous children from the Yanomami community in the Amazon over the past four years. This was a huge shock in Brazil, and the administration responded immediately. They sent task forces to the region and are now expelling the illegal miners that were bringing diseases and were ultimately responsible for these humanitarian tragedies. To be clear: It is still a problem. It’s not solved. But this is already a good example of positive action.

      Fighting deforestation in the Amazon and the Cerrado, another biome critical to climate regulation in Brazil, will not be easy. Rebuilding the environmental policy will take time, and the agencies responsible for enforcement are understaffed. In addition, environmental crime has become more sophisticated, connecting with other major criminal organizations in the country. In April, for the first time, there was a reduction in deforestation in the Amazon after two consecutive months of higher numbers. These are still preliminary data, and it is still too early to confirm whether they signal a turning point and may indicate a tendency for deforestation to decrease. On the other hand, the Cerrado registered record deforestation in April.

      There are problems everywhere in the economy and politics that Lula will have to face. In the first week of the new term, on Jan. 8, we saw an insurrection in Brasília, the country’s capital, from Bolsonaro voters who wouldn’t accept the election results. The events resembled what Americans saw in the Capitol attacks in 2021. We also seem to have imported problems from the United States, like mass killings in schools. We never used to have them in Brazil, but we are seeing them now. I’m curious to see how the country will address those problems and if the U.S. can also inspire solutions to that. That’s something I’m thinking about, being here: Are there solutions here? What are they?

      Q: What have you learned so far from MIT and your fellowship?

      A: It’s hard to put everything into words! I’m mostly taking courses and attending lectures on pressing issues to humanity, like existential threats such as climate change, artificial intelligence, biosecurity, and more.

      I’m learning about all these issues, but also, as a journalist, I think that I’m learning more about how I can incorporate the scientific approach into my work; for example, being more pro-positive. I am already a rigorous journalist, but I am thinking about how I can be more rigorous and more transparent about my methods. Being in the academic and scientific environment is inspiring that way.

      I am also learning a lot about how to cover scientific topics and thinking about how technology can offer us solutions (and problems). I’m learning so much that I think I will need some time to digest and fully understand what this period means for me!

      Q: You mentioned artificial intelligence. Would you like to weigh in on this subject and what you have been learning?

      A: It has been a particularly good semester to be at MIT. Generative artificial intelligence, which became more popular after ChatGPT, has been a topic of intense discussion this semester, and I was able to attend many classes, seminars, and events about AI here, especially from a policy perspective.

      Algorithms have influenced the economy, society, and public health for many years. It has had great outcomes, but also injustice. Popular systems like ChatGPT have made this technology incredibly popular and accessible, even for those with no computer knowledge. This is scary and, at the same time, very exciting. Here, I learned that we need guardrails for artificial intelligence, just like other technologies. Think of the pharmaceutical or automobile industries, which have to meet safety criteria before putting a new product on the market. But with artificial intelligence, it’s going to be different; supply chains are very complex and sometimes not very transparent, and the speed at which new resources develop is so fast that it challenges the policymaker’s ability to respond.

      Artificial intelligence is changing the world radically. It’s exciting to have the privilege of being here and seeing these discussions take place. After all, I have a future to report on. At least, I hope so!

      Q: What are you working on going forward?

      A: After MIT, I am going to New York, where I’ll be working with The New York Times in their internship program. I’m really excited about that because it will be a different pace from MIT. I am also doing research on carbon credit markets and hope to continue that project, either in a reporting or academic environment. 

      Honestly, I feel inspired to keep studying. I would love to spend more time here at MIT. I would love to do a master’s or join any program here. I’m going to work on coming back to academia because I think that I need to learn more from the academic environment. I hope that it’s at MIT because honestly, it’s the most exciting environment that I’ve ever been in, with all the people here from different fields and different backgrounds. I’m not a scientist, but it’s inspiring to be with them, and if there’s a way that I could contribute to their work in a way that they’re contributing to my work, I’ll be thrilled to spend more time here. More

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      in Energy

      Tackling the MIT campus’s top energy consumers, building by building

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      When staff in MIT’s Department of Facilities would visualize energy use and carbon-associated emissions by campus buildings, Building 46 always stood out — attributed to its energy intensity, which accounted for 8 percent of MIT’s total campus energy use. This high energy draw was not surprising, as the building is home of the Brain and Cognitive Sciences Complex and a large amount of lab space, but it also made the building a perfect candidate for an energy performance audit to seek out potential energy saving opportunities.

      This audit revealed that several energy efficiency updates to the building mechanical systems infrastructure, including optimization of the room-by-room ventilation rates, could result in an estimated 35 percent reduction of energy use, which would in turn lower MIT’s total greenhouse gas emissions by an estimated 2 percent — driving toward the Institute’s 2026 goal of net-zero and 2050 goal of elimination of direct campus emissions.

      Building energy efficiency projects are not new for MIT. Since 2010, MIT has been engaged in a partnership agreement with utility company Eversource establishing the Efficiency Forward program, empowering MIT to invest in more than 300 energy conservation projects to date and lowering energy consumption on campus for a total calculated savings of approximately 70 million kilowatt hours and 4.2 million therms. But at 418,000 gross square feet, Building 46 is the first energy efficiency project of its size on the campus.

      “We’ve never tackled a whole building like this — it’s the first capital project that is technically an energy project,” explains Siobhan Carr, energy efficiency program manager, who was part of the team overseeing the energy audit and lab ventilation performance assessment in the building. “That gives you an idea of the magnitude and complexity of this.”

      The project started with the full building energy assessment and lab ventilation risk audit. “We had a team go through every corner of the building and look at every possible opportunity to save energy,” explains Jessica Parks, senior project manager for systems performance and turnover in campus construction. “One of the biggest issues we saw was that there’s a lot of dry lab spaces which are basically offices, but they’re all getting the same ventilation as if they were a high-intensity lab.” Higher ventilation and more frequent air exchange rates draw more energy. By optimizing for the required ventilation rates, there was an opportunity to save energy in nearly every space in the building.

      In addition to the optimized ventilation, the project team will convert fume hoods from constant volume to variable volume and install equipment to help the building systems run more efficiently. The team also identified opportunities to work with labs to implement programs such as fume hood hibernation and unoccupied setbacks for temperature and ventilation. As different spaces in the building have varying needs, the energy retrofit will touch all 1,254 spaces in the building — one by one — to implement the different energy measures to reach that estimated 35 percent reduction in energy use.

      Although time-consuming and complex, this room-by-room approach has a big benefit in that it has allowed research to continue in the space largely uninterrupted. With a few exceptions, the occupants of Building 46, which include the Department of Brain and Cognitive Sciences, The McGovern Institute for Brain Research, and The Picower Institute for Learning and Memory, have remained in place for the duration of the project. Partners in the MIT Environment, Health and Safety Office are instrumental to this balance of renovations and keeping the building operational during the optimization efforts and are one of several teams across MIT contributing to building efficiency efforts.

      The completion date of the building efficiency project is set for 2024, but Carr says that some of the impact of this ongoing work may soon be seen. “We should start to see savings as we move through the building, and we expect to fully realize all of our projected savings a year after completion,” she says, noting that the length of time is required for a year-over-year perspective to see the full reduction in energy use.

      The impact of the project goes far beyond the footprint of Building 46 as it offers insights and spurred actions for future projects — including buildings 76 and 68, the number two and three top energy users on campus. Both buildings recently underwent their own energy audits and lab ventilation performance assessments. The energy efficiency team is now crafting a plan for full-building approaches, much like Building 46. “To date, 46 has presented many learning opportunities, such as how to touch every space in a building while research continues, as well as how to overcome challenges encountered when working on existing systems,” explains Parks. “The good news is that we have developed solutions for those challenges and the teams have been proactively implementing those lessons in our other projects.”

      Communication has proven to be another key for these large projects where occupants see the work happening and often play a role in answering questions about their unique space. “People are really engaged, they ask questions about the work, and we ask them about the space they’re in every day,” says Parks. “The Building 46 occupants have been wonderful partners as we worked in all of their spaces, which is paving the way for a successful project.”

      The release of Fast Forward in 2021 has also made communications easier, notes Carr, who says the plan helps to frame these projects as part of the big picture — not just a construction interruption. “Fast Forward has brought a visibility into what we’re doing within [MIT] Facilities on these buildings,” she says. “It brings more eyes and ears, and people understand that these projects are happening throughout campus and not just in their own space — we’re all working to reduce energy and to reduce greenhouse gas across campus.”

      The Energy Efficiency team will continue to apply that big-picture approach as ongoing building efficiency projects on campus are assessed to reach toward a 10 to 15 percent reduction in energy use and corresponding emissions over the next several years. More

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      in Environment

      River erosion can shape fish evolution, study suggests

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      If we could rewind the tape of species evolution around the world and play it forward over hundreds of millions of years to the present day, we would see biodiversity clustering around regions of tectonic turmoil. Tectonically active regions such as the Himalayan and Andean mountains are especially rich in flora and fauna due to their shifting landscapes, which act to divide and diversify species over time.

      But biodiversity can also flourish in some geologically quieter regions, where tectonics hasn’t shaken up the land for millennia. The Appalachian Mountains are a prime example: The range has not seen much tectonic activity in hundreds of millions of years, and yet the region is a notable hotspot of freshwater biodiversity.

      Now, an MIT study identifies a geological process that may shape the diversity of species in tectonically inactive regions. In a paper appearing today in Science, the researchers report that river erosion can be a driver of biodiversity in these older, quieter environments.

      They make their case in the southern Appalachians, and specifically the Tennessee River Basin, a region known for its huge diversity of freshwater fishes. The team found that as rivers eroded through different rock types in the region, the changing landscape pushed a species of fish known as the greenfin darter into different tributaries of the river network. Over time, these separated populations developed into their own distinct lineages.

      The team speculates that erosion likely drove the greenfin darter to diversify. Although the separated populations appear outwardly similar, with the greenfin darter’s characteristic green-tinged fins, they differ substantially in their genetic makeup. For now, the separated populations are classified as one single species. 

      “Give this process of erosion more time, and I think these separate lineages will become different species,” says Maya Stokes PhD ’21, who carried out part of the work as a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).

      The greenfin darter may not be the only species to diversify as a consequence of river erosion. The researchers suspect that erosion may have driven many other species to diversify throughout the basin, and possibly other tectonically inactive regions around the world.

      “If we can understand the geologic factors that contribute to biodiversity, we can do a better job of conserving it,” says Taylor Perron, the Cecil and Ida Green Professor of Earth, Atmospheric, and Planetary Sciences at MIT.

      The study’s co-authors include collaborators at Yale University, Colorado State University, the University of Tennessee, the University of Massachusetts at Amherst, and the Tennessee Valley Authority (TVA). Stokes is currently an assistant professor at Florida State University.

      Fish in trees

      The new study grew out of Stokes’ PhD work at MIT, where she and Perron were exploring connections between geomorphology (the study of how landscapes evolve) and biology. They came across work at Yale by Thomas Near, who studies lineages of North American freshwater fishes. Near uses DNA sequence data collected from freshwater fishes across various regions of North America to show how and when certain species evolved and diverged in relation to each other.

      Near brought a curious observation to the team: a habitat distribution map of the greenfin darter showing that the fish was found in the Tennessee River Basin — but only in the southern half. What’s more, Near had mitochondrial DNA sequence data showing that the fish’s populations appeared to be different in their genetic makeup depending on the tributary in which they were found.

      To investigate the reasons for this pattern, Stokes gathered greenfin darter tissue samples from Near’s extensive collection at Yale, as well as from the field with help from TVA colleagues. She then analyzed DNA sequences from across the entire genome, and compared the genes of each individual fish to every other fish in the dataset. The team then created a phylogenetic tree of the greenfin darter, based on the genetic similarity between fish.

      From this tree, they observed that fish within a tributary were more related to each other than to fish in other tributaries. What’s more, fish within neighboring tributaries were more similar to each other than fish from more distant tributaries.

      “Our question was, could there have been a geological mechanism that, over time, took this single species, and splintered it into different, genetically distinct groups?” Perron says.

      A changing landscape

      Stokes and Perron started to observe a “tight correlation” between greenfin darter habitats and the type of rock where they are found. In particular, much of the southern half of the Tennessee River Basin, where the species abounds, is made of metamorphic rock, whereas the northern half consists of sedimentary rock, where the fish are not found.

      They also observed that the rivers running through metamorphic rock are steeper and more narrow, which generally creates more turbulence, a characteristic greenfin darters seem to prefer. The team wondered: Could the distribution of greenfin darter habitat have been shaped by a changing landscape of rock type, as rivers eroded into the land over time?

      To check this idea, the researchers developed a model to simulate how a landscape evolves as rivers erode through various rock types. They fed the model information about the rock types in the Tennessee River Basin today, then ran the simulation back to see how the same region may have looked millions of years ago, when more metamorphic rock was exposed.

      They then ran the model forward and observed how the exposure of metamorphic rock shrank over time. They took special note of where and when connections between tributaries crossed into non-metamorphic rock, blocking fish from passing between those tributaries. They drew up a simple timeline of these blocking events and compared this to the phylogenetic tree of diverging greenfin darters. The two were remarkably similar: The fish seemed to form separate lineages in the same order as when their respective tributaries became separated from the others.

      “It means it’s plausible that erosion through different rock layers caused isolation between different populations of the greenfin darter and caused lineages to diversify,” Stokes says.

      “This study is highly compelling because it reveals a much more subtle but powerful mechanism for speciation in passive margins,” says Josh Roering, professor of Earth sciences at the University of Oregon, who was not involved in the study. “Stokes and Perron have revealed some of the intimate connections between aquatic species and geology that may be much more common than we realize.”

      This research was supported, in part, by the mTerra Catalyst Fund and the U.S. National Science Foundation through the AGeS Geochronology Program and the Graduate Research Fellowship Program. While at MIT, Stokes received support through the Martin Fellowship for Sustainability and the Hugh Hampton Young Fellowship. More

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      in Energy

      MIT junior Anushree Chaudhuri named 2023 Udall Scholar

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      MIT junior Anushree Chaudhuri has been selected as a 2023 Morris K. Udall and Stewart L. Udall Foundation Scholar. She is only the second MIT student to win this award and the first winner since 2008.

      The Udall Scholarship honors students who have demonstrated a commitment to the environment, Native American health care, or tribal public policy. Chaudhuri is one of 55 Udall Scholars selected nationally out of 384 nominated applicants.

      Chaudhuri, who hails from San Diego, studies urban studies and planning as well as economics at MIT. She plans to work across the public and private sectors to drive structural changes that connect the climate crisis to local issues and inequities. Chaudhuri has conducted research with the MIT Environmental Solutions Initiative Rapid Response Group, which develops science-based analysis on critical environmental issues for community partners in civil society, government, and industry.

      Throughout her sophomore year, Chaudhuri worked with MIT’s Office of Sustainability, creating data visualizations for travel and Scope 3 emissions as a resource for MIT departments, labs, and centers. As an MIT Washington intern at the U.S. Department of Energy, she also developed the Buildings Upgrade Equity Tool to assist local governments in identifying areas for decarbonization investments.

      While taking Bruno Verdini’s class 11.011 (Art and Science of Negotiation) in fall 2021, Chaudhuri became deeply interested in the field of dispute resolution as a way of engaging diverse stakeholders in collaborative problem-solving, and she began work with Professor Lawrence Susskind at the MIT Science Impact Collaborative. She has now completed multiple projects with the group, as part of the MIT Renewable Energy Siting Clinic, including creating qualitative case studies to inform mediated siting processes and developing an open-access website and database for 60 renewable energy siting conflicts from findings published in Energy Policy. Through the MIT Climate and Sustainability Consortium’s Climate Scholars Program and a DUSP-PKG Fellowship, she is conducting an ethnographic and econometric study on the energy justice impacts of clean infrastructure on local communities.

      As part of a yearlong campaign to revise MIT’s Fast Forward Climate Action Plan, Chaudhuri led the Investments Student Working Group, which advocated for institutional social responsibility and active engagement in the Climate Action 100+ investor coalition. She also served as chair of the Undergraduate Association Committee on Sustainability and co-leads the Student Sustainability Coalition. Her work led her to be selected by MIT as an undergraduate delegate to the U.N. Framework Convention on Climate Change Summit (COP27).

      Chaudhuri’s research experiences and leadership in campus sustainability organizations have strengthened her belief in deep community engagement as a catalyst for change. By taking an interdisciplinary approach that combines law, planning, conflict resolution, participatory research, and data science, she’s committed to a public service career creating policies that are human-centered and address climate injustices, creating co-benefits for diverse communities. More

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      Six ways MIT is taking action on climate

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      From reuse and recycling to new carbon markets, events during Earth Month at MIT spanned an astonishing range of ideas and approaches to tackling the climate crisis. The MIT Climate Nucleus offered funding to departments and student organizations to develop programming that would showcase the countless initiatives underway to make a better world.

      Here are six — just six of many — ways the MIT community is making a difference on climate right now.

      1. Exchanging knowledge with policymakers to meet local, regional, and global challenges

      Creating solutions begins with understanding the problem.

      Speaking during the annual Earth Day Colloquium of the MIT Energy Initiative (MITEI) about the practical challenges of implementing wind-power projects, for instance, Massachusetts State Senator Michael J. Barrett offered a sobering assessment.

      The senate chair of the Joint Committee on Telecommunications, Utilities, and Energy, Barrett reported that while the coast of Massachusetts provides a conducive site for offshore wind, economic forces have knocked a major offshore wind installation project off track. The combination of the pandemic and global geopolitical instability has led to such great supply chain disruptions and rising commodity costs that a project considered necessary for the state to meet its near-term climate goals now faces delays, he said.

      Like others at MIT, MITEI researchers keep their work grounded in the real-world constraints and possibilities for decarbonization, engaging with policymakers and industry to understand the on-the-ground challenges to technological and policy-based solutions and highlight the opportunities for greatest impact.

      2. Developing new ways to prevent, mitigate, and adapt to the effects of climate change

      An estimated 20 percent of MIT faculty work on some aspect of the climate crisis, an enormous research effort distributed throughout the departments, labs, centers, and institutes.

      About a dozen such projects were on display at a poster session coordinated by the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), Environmental Solutions Initiative (ESI), and MITEI.

      Students and postdocs presented innovations including:

      Graduate student Alexa Reese Canaan describes her research on household energy consumption to Massachusetts State Senator Michael J. Barrett, chair of the Joint Committee on Telecommunications, Utilities, and Energy.

      Photo: Caitlin Cunningham

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      3. Preparing students to meet the challenges of a climate-changed world

      Faculty and staff from more than 30 institutions of higher education convened at the MIT Symposium on Advancing Climate Education to exchange best practices and innovations in teaching and learning. Speakers and participants considered paths to structural change in higher education, the imperative to place equity and justice at the center of new educational approaches, and what it means to “educate the whole student” so that graduates are prepared to live and thrive in a world marked by global environmental and economic disruption.

      Later in April, MIT faculty voted to approve the creation of a new joint degree program in climate system science and engineering.

      4. Offering climate curricula to K-12 teachers

      At a daylong conference on climate education for K-12 schools, the attendees were not just science teachers. Close to 50 teachers of arts, literature, history, math, mental health, English language, world languages, and even carpentry were all hungry for materials and approaches to integrate into their curricula. They were joined by another 50 high school students, ready to test out the workshops and content developed by MIT Climate Action Through Education (CATE), which are already being piloted in at least a dozen schools.

      The CATE initiative is led by Christopher Knittel, the George P. Shultz Professor of Energy Economics at the MIT Sloan School of Management, deputy director for policy at MITEI, and faculty director of the MIT Center for Energy and Environmental Policy Research. The K-12 Climate Action and Education Conference was hosted as a collaboration with the Massachusetts Teachers Association Climate Action Network and Earth Day Boston.

      “We will be honest about the threats posed by climate change, but also give students a sense of agency that they can do something about this,” Knittel told MITEI Energy Futures earlier this spring. “And for the many teachers — especially non-science teachers — starved for knowledge and background material, CATE offers resources to give them confidence to implement our curriculum.”

      High school students and K-12 teachers participated in a workshop on “Exploring a Green City,” part of the Climate Action and Education Conference on April 1.

      Photo: Tony Rinaldo

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      5. Guiding our communities in making sense of the coming changes

      The arts and humanities, vital in their own right, are also central to the sharing of scientific knowledge and its integration into culture, behavior, and decision-making. A message well-delivered can reach new audiences and prompt reflection and reckoning on ethics and values, identity, and optimism.

      The Climate Machine, part of ESI’s Arts and Climate program, produced an evening art installation on campus featuring dynamic, large-scale projections onto the façade of MIT’s new music building and a musical performance by electronic duo Warung. Passers-by were invited to take a Climate Identity Quiz, with the responses reflected in the visuals. Another exhibit displayed the results of a workshop in which attendees had used an artificial intelligence art tool to imagine the future of their hometowns, while another highlighted native Massachusetts wildlife.

      The Climate Machine is an MIT research project undertaken in collaboration with record label Anjunabeats. The collaborative team imagines interactive experiences centered on sustainability that could be deployed at musical events and festivals to inspire climate action.

      Dillon Ames (left) and Aaron Hopkins, known as the duo Warung, perform a live set during the Climate Machine art installation.

      Photo: Caitlin Cunningham

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      6. Empowering students to seize this unique policy moment

      ESI’s TILclimate Podcast, which breaks down important climate topics for general listeners, held a live taping at the MIT Museum and offered an explainer on three recent, major pieces of federal legislation: the Inflation Reduction Act of 2022, the Bipartisan Infrastructure Bill of 2021, and the CHIPS and Science Act of 2022.

      The combination of funding and financial incentives for energy- and climate-related projects, along with reinvestment in industrial infrastructure, create “a real moment and an opportunity,” said special guest Elisabeth Reynolds, speaking with host Laur Hesse Fisher. Reynolds was a member of the National Economic Council from 2021 to 2022, serving as special assistant to the president for manufacturing and economic development; after leaving the White House, Reynolds returned to MIT, where she is a lecturer in MIT’s Department of Urban Studies and Planning.

      For students, the opportunities to engage have never been better, Reynolds urged: “There is so much need. … Find a way to contribute, and find a way to help us make this transformation.”

      “What we’re embarking on now, you just can’t overstate the significance of it,” she said.

      For more information on how MIT is advancing climate action across education; research and innovation; policy; economic, social, and environmental justice; public and global engagement; sustainable campus operations; and more, visit Fast Forward: MIT’s Climate Action Plan for the Decade. The actions described in the plan aim to accelerate the global transition to net-zero carbon emissions, and to “educate and empower the next generation.” More

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      in Environment

      3 Questions: Can disused croplands help mitigate climate change?

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      As the world struggles to meet internationally agreed targets for reducing greenhouse gas emissions, methods of removing carbon dioxide such as reforestation of cleared areas have become an increasingly important strategy. But little attention has been paid to the potential for abandoned or marginal croplands to be restored to natural vegetation as an additional carbon sink, say MIT assistant professor of civil and environmental engineering César Terrer, recent visiting MIT doctoral student Stephen M. Bell, and six others, in a recent open-access paper in the journal Nature Communications. Here, Terrer and Bell explain the potential use of these “post-agricultural” lands to help in the fight against damaging climate change.

      Q: How significant is the potential of unused agricultural lands as a carbon sink to help mitigate climate change?

      Bell: We know of these huge instances of land abandonment and post-agricultural succession throughout history, like following the collapse of major cities from ancient Mesopotamia to the Mayans. And when the Europeans arrived in the Americas in the 15th century, so many people died and so much forest grew back on abandoned farmland that it helped cool the entire planet and was potentially a driver of the coldest part of the so-called “Little Ice Age” period.

      Today, we have abandoned farmland all over the Mediterranean region, where I did my PhD field work. As young people left rural areas for the cities throughout the 20th century, farmers couldn’t pass on their land to anyone, and the land succeeded back into shrub lands and forests. The biggest recent example of abandonment is for sure the collapse of the Soviet Union, where an estimated 60 million hectares of forest regrew when support for collective farming stopped, resulting in one of the largest carbon sinks ever attributed to a single event.

      So, when we look back at the past, we know there’s potential. Of course, these are huge events, and no one is proposing to replicate anything like that. We need to use land for multiple purposes, but looking back at these big examples, we know there is potential for abandoned or restored agricultural land to be carbon sinks. And so that tells us to dig deeper into this question and get a better idea of realistic scenarios, a better understanding of the climate change mitigation potential of agricultural cessation in the most strategic places.

      Terrer: More than 115 billion tons of carbon have been lost from soils due to agricultural practices that disturb soil integrity — such as tilling, monoculture farming, removing crop residue, excessive use of fertilizers and pesticides, and over-grazing. To put this into perspective, the amount of carbon lost is equivalent to the total CO2 emissions ever produced in the United States.

      Our current research synthesizes field data from thousands of experiments, aiming to understand the factors that influence soil carbon accrual in abandoned croplands transitioning back to forests or natural grasslands. We’re working to quantify the potential for carbon sequestration in these soils over 30-, 50-, and 100-year time frames and mapping the areas with the greatest potential for carbon storage. This includes both increases in soil carbon and in vegetation biomass.

      Q: What are some of the key uncertainties in evaluating this potential for unused cropland to serve as a carbon sink, and how could those uncertainties be addressed?

      Bell: We use this word uncertainties in two ways. Specifically, the longevity of potential recarbonization, and the intensity of the potential recarbonization. Those are two factors, two aspects that we need to quantify to reduce our uncertainty.

      So, how long will the land recarbonize, regardless of the intensity? If the carbon level is going up, that’s good. If there’s more carbon increasing in the soil, we know that it came from somewhere, it came from the atmosphere. But how long does that happen? We know soil can get saturated. It can reach its carbon capacity limit, it won’t continue to increase the carbon stock, and the recarbonization curve will flatten out. When does that happen? Is it after a hundred years? Is it after 20 years?

      But the world’s soils are very diverse and complex, so what might be true in one place is not true in another place. It may take a longer time to reach saturation for more fertile soils in the Midwest U.S. than less fertile soils in the Southwest, for example. Alternatively, sometimes soils in drier areas like in the Southwest may never reach true saturation if they are degraded and have stalled recovery following abandonment.

      The second uncertainty is intensity: How high on the y-axis on the chart of recarbonization does saturation occur? With the analogy comparing U.S. soils, you might have a relatively huge carbon increase on an abandoned farm in the Southwest, but because the soil is not very carbon-rich it’s not a large increase in absolute terms. In the Midwest, there might only be a small relative increase, but that increase could be much more in total than in the Southwest. These are just nuances to keep in mind as we look at this at the global scale.

      These nuances are essentially uncertainties. Soil carbon responses to agricultural land abandonment is complicated, and unfortunately it hasn’t been studied in much detail so far. We need to reduce those uncertainties to get a better understanding of the recarbonization potential. This is easier said than done because not only do we have these temporal data uncertainties, but we also have spatial uncertainties. We don’t have very good maps of past and present post-agricultural landscapes.

      Q: Can this potential use of post-agricultural lands be implemented without putting global food supplies at risk? How can these needs be balanced?

      Terrer: As to whether utilizing post-agricultural lands for carbon sequestration can be implemented without jeopardizing global food supplies, and how to balance these needs, our recent research provides valuable insights.

      The challenge, of course, lies in balancing cropland restoration for climate mitigation with food security for a growing global population. Abandoned croplands represent an opportunity for carbon sequestration without impacting active agricultural lands. However, the available area of abandoned croplands is insufficient to make a substantial impact on climate mitigation on its own.

      Thus, our proposal also emphasizes the importance of closing yield gaps, which involves increasing crop production per hectare to its theoretical limits. This would enable us to maintain or even increase global crop yields using only a fraction of the currently cultivated area, allowing the remaining land to be dedicated to climate mitigation efforts. By pursuing this strategy, we estimate that over half of the amount of soil carbon lost so far due to agriculture could be recovered, while ensuring food security for the world’s population. More