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    A new sensor detects harmful “forever chemicals” in drinking water

    MIT chemists have designed a sensor that detects tiny quantities of perfluoroalkyl and polyfluoroalkyl substances (PFAS) — chemicals found in food packaging, nonstick cookware, and many other consumer products.

    These compounds, also known as “forever chemicals” because they do not break down naturally, have been linked to a variety of harmful health effects, including cancer, reproductive problems, and disruption of the immune and endocrine systems.

    Using the new sensor technology, the researchers showed that they could detect PFAS levels as low as 200 parts per trillion in a water sample. The device they designed could offer a way for consumers to test their drinking water, and it could also be useful in industries that rely heavily on PFAS chemicals, including the manufacture of semiconductors and firefighting equipment.

    “There’s a real need for these sensing technologies. We’re stuck with these chemicals for a long time, so we need to be able to detect them and get rid of them,” says Timothy Swager, the John D. MacArthur Professor of Chemistry at MIT and the senior author of the study, which appears this week in the Proceedings of the National Academy of Sciences.

    Other authors of the paper are former MIT postdoc and lead author Sohyun Park and MIT graduate student Collette Gordon.

    Detecting PFAS

    Coatings containing PFAS chemicals are used in thousands of consumer products. In addition to nonstick coatings for cookware, they are also commonly used in water-repellent clothing, stain-resistant fabrics, grease-resistant pizza boxes, cosmetics, and firefighting foams.

    These fluorinated chemicals, which have been in widespread use since the 1950s, can be released into water, air, and soil, from factories, sewage treatment plants, and landfills. They have been found in drinking water sources in all 50 states.

    In 2023, the Environmental Protection Agency created an “advisory health limit” for two of the most hazardous PFAS chemicals, known as perfluorooctanoic acid (PFOA) and perfluorooctyl sulfonate (PFOS). These advisories call for a limit of 0.004 parts per trillion for PFOA and 0.02 parts per trillion for PFOS in drinking water.

    Currently, the only way that a consumer could determine if their drinking water contains PFAS is to send a water sample to a laboratory that performs mass spectrometry testing. However, this process takes several weeks and costs hundreds of dollars.

    To create a cheaper and faster way to test for PFAS, the MIT team designed a sensor based on lateral flow technology — the same approach used for rapid Covid-19 tests and pregnancy tests. Instead of a test strip coated with antibodies, the new sensor is embedded with a special polymer known as polyaniline, which can switch between semiconducting and conducting states when protons are added to the material.

    The researchers deposited these polymers onto a strip of nitrocellulose paper and coated them with a surfactant that can pull fluorocarbons such as PFAS out of a drop of water placed on the strip. When this happens, protons from the PFAS are drawn into the polyaniline and turn it into a conductor, reducing the electrical resistance of the material. This change in resistance, which can be measured precisely using electrodes and sent to an external device such as a smartphone, gives a quantitative measurement of how much PFAS is present.

    This approach works only with PFAS that are acidic, which includes two of the most harmful PFAS — PFOA and perfluorobutanoic acid (PFBA).

    A user-friendly system

    The current version of the sensor can detect concentrations as low as 200 parts per trillion for PFBA, and 400 parts per trillion for PFOA. This is not quite low enough to meet the current EPA guidelines, but the sensor uses only a fraction of a milliliter of water. The researchers are now working on a larger-scale device that would be able to filter about a liter of water through a membrane made of polyaniline, and they believe this approach should increase the sensitivity by more than a hundredfold, with the goal of meeting the very low EPA advisory levels.

    “We do envision a user-friendly, household system,” Swager says. “You can imagine putting in a liter of water, letting it go through the membrane, and you have a device that measures the change in resistance of the membrane.”

    Such a device could offer a less expensive, rapid alternative to current PFAS detection methods. If PFAS are detected in drinking water, there are commercially available filters that can be used on household drinking water to reduce those levels. The new testing approach could also be useful for factories that manufacture products with PFAS chemicals, so they could test whether the water used in their manufacturing process is safe to release into the environment.

    The research was funded by an MIT School of Science Fellowship to Gordon, a Bose Research Grant, and a Fulbright Fellowship to Park. More

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    MIT researchers remotely map crops, field by field

    Crop maps help scientists and policymakers track global food supplies and estimate how they might shift with climate change and growing populations. But getting accurate maps of the types of crops that are grown from farm to farm often requires on-the-ground surveys that only a handful of countries have the resources to maintain.

    Now, MIT engineers have developed a method to quickly and accurately label and map crop types without requiring in-person assessments of every single farm. The team’s method uses a combination of Google Street View images, machine learning, and satellite data to automatically determine the crops grown throughout a region, from one fraction of an acre to the next. 

    The researchers used the technique to automatically generate the first nationwide crop map of Thailand — a smallholder country where small, independent farms make up the predominant form of agriculture. The team created a border-to-border map of Thailand’s four major crops — rice, cassava, sugarcane, and maize — and determined which of the four types was grown, at every 10 meters, and without gaps, across the entire country. The resulting map achieved an accuracy of 93 percent, which the researchers say is comparable to on-the-ground mapping efforts in high-income, big-farm countries.

    The team is applying their mapping technique to other countries such as India, where small farms sustain most of the population but the type of crops grown from farm to farm has historically been poorly recorded.

    “It’s a longstanding gap in knowledge about what is grown around the world,” says Sherrie Wang, the d’Arbeloff Career Development Assistant Professor in MIT’s Department of Mechanical Engineering, and the Institute for Data, Systems, and Society (IDSS). “The final goal is to understand agricultural outcomes like yield, and how to farm more sustainably. One of the key preliminary steps is to map what is even being grown — the more granularly you can map, the more questions you can answer.”

    Wang, along with MIT graduate student Jordi Laguarta Soler and Thomas Friedel of the agtech company PEAT GmbH, will present a paper detailing their mapping method later this month at the AAAI Conference on Artificial Intelligence.

    Ground truth

    Smallholder farms are often run by a single family or farmer, who subsist on the crops and livestock that they raise. It’s estimated that smallholder farms support two-thirds of the world’s rural population and produce 80 percent of the world’s food. Keeping tabs on what is grown and where is essential to tracking and forecasting food supplies around the world. But the majority of these small farms are in low to middle-income countries, where few resources are devoted to keeping track of individual farms’ crop types and yields.

    Crop mapping efforts are mainly carried out in high-income regions such as the United States and Europe, where government agricultural agencies oversee crop surveys and send assessors to farms to label crops from field to field. These “ground truth” labels are then fed into machine-learning models that make connections between the ground labels of actual crops and satellite signals of the same fields. They then label and map wider swaths of farmland that assessors don’t cover but that satellites automatically do.

    “What’s lacking in low- and middle-income countries is this ground label that we can associate with satellite signals,” Laguarta Soler says. “Getting these ground truths to train a model in the first place has been limited in most of the world.”

    The team realized that, while many developing countries do not have the resources to maintain crop surveys, they could potentially use another source of ground data: roadside imagery, captured by services such as Google Street View and Mapillary, which send cars throughout a region to take continuous 360-degree images with dashcams and rooftop cameras.

    In recent years, such services have been able to access low- and middle-income countries. While the goal of these services is not specifically to capture images of crops, the MIT team saw that they could search the roadside images to identify crops.

    Cropped image

    In their new study, the researchers worked with Google Street View (GSV) images taken throughout Thailand — a country that the service has recently imaged fairly thoroughly, and which consists predominantly of smallholder farms.

    Starting with over 200,000 GSV images randomly sampled across Thailand, the team filtered out images that depicted buildings, trees, and general vegetation. About 81,000 images were crop-related. They set aside 2,000 of these, which they sent to an agronomist, who determined and labeled each crop type by eye. They then trained a convolutional neural network to automatically generate crop labels for the other 79,000 images, using various training methods, including iNaturalist — a web-based crowdsourced  biodiversity database, and GPT-4V, a “multimodal large language model” that enables a user to input an image and ask the model to identify what the image is depicting. For each of the 81,000 images, the model generated a label of one of four crops that the image was likely depicting — rice, maize, sugarcane, or cassava.

    The researchers then paired each labeled image with the corresponding satellite data taken of the same location throughout a single growing season. These satellite data include measurements across multiple wavelengths, such as a location’s greenness and its reflectivity (which can be a sign of water). 

    “Each type of crop has a certain signature across these different bands, which changes throughout a growing season,” Laguarta Soler notes.

    The team trained a second model to make associations between a location’s satellite data and its corresponding crop label. They then used this model to process satellite data taken of the rest of the country, where crop labels were not generated or available. From the associations that the model learned, it then assigned crop labels across Thailand, generating a country-wide map of crop types, at a resolution of 10 square meters.

    This first-of-its-kind crop map included locations corresponding to the 2,000 GSV images that the researchers originally set aside, that were labeled by arborists. These human-labeled images were used to validate the map’s labels, and when the team looked to see whether the map’s labels matched the expert, “gold standard” labels, it did so 93 percent of the time.

    “In the U.S., we’re also looking at over 90 percent accuracy, whereas with previous work in India, we’ve only seen 75 percent because ground labels are limited,” Wang says. “Now we can create these labels in a cheap and automated way.”

    The researchers are moving to map crops across India, where roadside images via Google Street View and other services have recently become available.

    “There are over 150 million smallholder farmers in India,” Wang says. “India is covered in agriculture, almost wall-to-wall farms, but very small farms, and historically it’s been very difficult to create maps of India because there are very sparse ground labels.”

    The team is working to generate crop maps in India, which could be used to inform policies having to do with assessing and bolstering yields, as global temperatures and populations rise.

    “What would be interesting would be to create these maps over time,” Wang says. “Then you could start to see trends, and we can try to relate those things to anything like changes in climate and policies.” More

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    Anushree Chaudhuri: Involving local communities in renewable energy planning

    Anushree Chaudhuri has a history of making bold decisions. In fifth grade, she biked across her home state of California with little prior experience. In her first year at MIT, she advocated for student recommendations in the preparation of the Institute’s Climate Action Plan for the Decade. And recently, she led a field research project throughout California to document the perspectives of rural and Indigenous populations affected by climate change and clean energy projects.

    “It doesn’t matter who you are or how young you are, you can get involved with something and inspire others to do so,” the senior says.

    Initially a materials science and engineering major, Chaudhuri was quickly drawn to environmental policy issues and later decided to double-major in urban studies and planning and in economics. Chaudhuri will receive her bachelor’s degrees this month, followed by a master’s degree in city planning in the spring.

    The importance of community engagement in policymaking has become one of Chaudhuri’s core interests. A 2024 Marshall Scholar, she is headed to the U.K. next year to pursue a PhD related to environment and development. She hopes to build on her work in California and continue to bring attention to impacts that energy transitions can have on local communities, which tend to be rural and low-income. Addressing resistance to these projects can be challenging, but “ignoring it leaves these communities in the dust and widens the urban-rural divide,” she says.

    Silliness and sustainability 

    Chaudhuri classifies her many activities into two groups: those that help her unwind, like her living community, Conner Two, and those that require intensive deliberation, like her sustainability-related organizing.

    Conner Two, in the Burton-Conner residence hall, is where Chaudhuri feels most at home on campus. She describes the group’s activities as “silly” and emphasizes their love of jokes, even in the floor’s nickname, “the British Floor,” which is intentionally absurd, as the residents are rarely British.

    Chaudhuri’s first involvement with sustainability issues on campus was during the preparation of MIT’s Fast Forward Climate Action Plan in the 2020-2021 academic year. As a co-lead of one of several student working groups, she helped organize key discussions between the administration, climate experts, and student government to push for six main goals in the plan, including an ethical investing framework. Being involved with a significant student movement so early on in her undergraduate career was a learning opportunity for Chaudhuri and impressed upon her that young people can play critical roles in making far-reaching structural changes.

    The experience also made her realize how many organizations on campus shared similar goals even if their perspectives varied, and she saw the potential for more synergy among them.

    Chaudhuri went on to co-lead the Student Sustainability Coalition to help build community across the sustainability-related organizations on campus and create a centralized system that would make it easier for outsiders and group members to access information and work together. Through the coalition, students have collaborated on efforts including campus events, and off-campus matters such as the Cambridge Green New Deal hearings.

    Another benefit to such a network: It creates a support system that recognizes even small-scale victories. “Community is so important to avoid burnout when you’re working on something that can be very frustrating and an uphill battle like negotiating with leadership or seeking policy changes,” Chaudhuri says.

    Fieldwork

    For the past year, Chaudhuri has been doing independent research in California with the support of several advisory organizations to host conversations with groups affected by renewable energy projects, which, as she has documented, are often concentrated in rural, low-income, and Indigenous communities. The introduction of renewable energy facilities, such as wind and solar farms, can perpetuate existing inequities if they ignore serious community concerns, Chaudhuri says.

    As state or federal policymakers and private developers carry out the permitting process for these projects, “they can repeat histories of extraction, sometimes infringing on the rights of a local or Tribal government to decide what happens with their land,” she says.

    In her site visits, she is documenting community opposition to controversial solar and wind proposals and collecting oral histories. Doing fieldwork for the first time as an outsider was difficult for Chaudhuri, as she dealt with distrust, unpredictability, and needing to be completely flexible for her sources. “A lot of it was just being willing to drop everything and go and be a little bit adventurous and take some risks,” she says.

    Role models and reading

    Chaudhuri is quick to credit many of the role models and other formative influences in her life.

    After working on the Climate Action Plan, Chaudhuri attended a public narrative workshop at Harvard University led by Marshall Ganz, a grassroots community organizer who worked with Cesar Chavez and on the 2008 Obama presidential campaign. “That was a big inspiration and kind of shaped how I viewed leadership in, for example, campus advocacy, but also in other projects and internships.”

    Reading has also influenced Chaudhuri’s perspective on community organizing, “After the Climate Action Plan campaign, I realized that a lot of what made the campaign successful or not could track well with organizing and social change theories, and histories of social movements. So, that was a good experience for me, being able to critically reflect on it and tie it into these other things I was learning about.”

    Since beginning her studies at MIT, Chaudhuri has become especially interested in social theory and political philosophy, starting with ancient forms of Western and Eastern ethic, and up to 20th and 21st century philosophers who inspire her. Chaudhuri cites Amartya Sen and Olúfẹ́mi Táíwò as particularly influential. “I think [they’ve] provided a really compelling framework to guide a lot of my own values,” she says.

    Another role model is Brenda Mallory, the current chair of the U.S. Council on Environmental Quality, who Chaudhuri was grateful to meet at the United Nations COP27 Climate Conference. As an intern at the U.S. Department of Energy, Chaudhuri worked within a team on implementing the federal administration’s Justice40 initiative, which commits 40 percent of federal climate investments to disadvantaged communities. This initiative was largely directed by Mallory, and Chaudhuri admires how Mallory was able to make an impact at different levels of government through her leadership. Chaudhuri hopes to follow in Mallory’s footsteps someday, as a public official committed to just policies and programs.

     “Good leaders are those who empower good leadership in others,” Chaudhuri says. More

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    Study measures the psychological toll of wildfires

    Wildfires in Southeast Asia significantly affect peoples’ moods, especially if the fires originate outside a person’s own country, according to a new study.

    The study, which measures sentiment by analyzing large amounts of social media data, helps show the psychological toll of wildfires that result in substantial air pollution, at a time when such fires are becoming a high-profile marker of climate change.  

    “It has a substantial negative impact on people’s subjective well-being,” says Siqi Zheng, an MIT professor and co-author of a new paper detailing the results. “This is a big effect.”

    The magnitude of the effect is about the same as another shift uncovered through large-scale studies of sentiment expressed online: When the weekend ends and the work week starts, people’s online postings reflect a sharp drop in mood. The new study finds that daily exposure to typical wildfire smoke levels in the region produces an equivalently large change in sentiment.

    “People feel anxious or sad when they have to go to work on Monday, and what we find with the fires is that this is, in fact, comparable to a Sunday-to-Monday sentiment drop,” says co-author Rui Du, a former MIT postdoct who is now an economist at Oklahoma State University.

    The paper, “Transboundary Vegetation Fire Smoke and Expressed Sentiment: Evidence from Twitter,” has been published online in the Journal of Environmental Economics and Management.

    The authors are Zheng, who is the STL Champion Professor of Urban and Real Estate Sustainability in the Center for Real Estate and the Department of Urban Studies and Planning at MIT; Du, an assistant professor of economics at Oklahoma State University’s Spears School of Business; Ajkel Mino, of the Department of Data Science and Knowledge Engineering at Maastricht University; and Jianghao Wang, of the Institute of Geographic Sciences and Natural Resources Research at the Chinese Academy of Sciences.

    The research is based on an examination of the events of 2019 in Southeast Asia, in which a huge series of Indonesian wildfires, seemingly related to climate change and deforestation for the palm oil industry, produced a massive amount of haze in the region. The air-quality problems affected seven countries: Brunei, Indonesia, Malaysia, Philippines, Singapore, Thailand, and Vietnam.

    To conduct the study, the scholars produced a large-scale analysis of postings from 2019 on X (formerly known as Twitter) to sample public sentiment. The study involved 1,270,927 tweets from 378,300 users who agreed to have their locations made available. The researchers compiled the data with a web crawler program and multilingual natural language processing applications that review the content of tweets and rate them in affective terms based on the vocabulary used. They also used satellite data from NASA and NOAA to create a map of wildfires and haze over time, linking that to the social media data.

    Using this method creates an advantage that regular public-opinion polling does not have: It creates a measurement of mood that is effectively a real-time metric rather than an after-the-fact assessment. Moreover, substantial wind shifts in the region at the time in 2019 essentially randomize which countries were exposed to more haze at various points, making the results less likely to be influenced by other factors.

    The researchers also made a point to disentangle the sentiment change due to wildfire smoke and that due to other factors. After all, people experience mood changes all the time from various natural and socioeconomic events. Wildfires may be correlated with some of them, which makes it hard to tease out the singular effect of the smoke. By comparing only the difference in exposure to wildfire smoke, blown in by wind, within the same locations over time, this study is able to isolate the impact of local wildfire haze on mood, filtering out nonpollution influences.

    “What we are seeing from our estimates is really just the pure causal effect of the transboundary wildfire smoke,” Du says.

    The study also revealed that people living near international borders are much more likely to be upset when affected by wildfire smoke that comes from a neighboring country. When similar conditions originate in their own country, there is a considerably more muted reaction.

    “Notably, individuals do not seem to respond to domestically produced fire plumes,” the authors write in the paper. The small size of many countries in the region, coupled with a fire-prone climate, make this an ongoing source of concern, however.

    “In Southeast Asia this is really a big problem, with small countries clustered together,” Zheng observes.

    Zheng also co-authored a 2022 study using a related methodology to study the impact of the Covid-19 pandemic on the moods of residents in about 100 countries. In that case, the research showed that the global pandemic depressed sentiment about 4.7 times as much as the normal Sunday-to-Monday shift.

    “There was a huge toll of Covid on people’s sentiment, and while the impact of the wildfires was about one-fifth of Covid, that’s still quite large,” Du says.

    In policy terms, Zheng suggests that the global implications of cross-border smoke pollution could give countries a shared incentive to cooperate further. If one country’s fires become another country’s problem, they may all have reason to limit them. Scientists warn of a rising number of wildfires globally, fueled by climate change conditions in which more fires can proliferate, posing a persistent threat across societies.

    “If they don’t work on this collaboratively, it could be damaging to everyone,” Zheng says.

    The research at MIT was supported, in part, by the MIT Sustainable Urbanization Lab. Jianghao Wang was supported by the National Natural Science Foundation of China. More

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    Study: Global deforestation leads to more mercury pollution

    About 10 percent of human-made mercury emissions into the atmosphere each year are the result of global deforestation, according to a new MIT study.

    The world’s vegetation, from the Amazon rainforest to the savannahs of sub-Saharan Africa, acts as a sink that removes the toxic pollutant from the air. However, if the current rate of deforestation remains unchanged or accelerates, the researchers estimate that net mercury emissions will keep increasing.

    “We’ve been overlooking a significant source of mercury, especially in tropical regions,” says Ari Feinberg, a former postdoc in the Institute for Data, Systems, and Society (IDSS) and lead author of the study.

    The researchers’ model shows that the Amazon rainforest plays a particularly important role as a mercury sink, contributing about 30 percent of the global land sink. Curbing Amazon deforestation could thus have a substantial impact on reducing mercury pollution.

    The team also estimates that global reforestation efforts could increase annual mercury uptake by about 5 percent. While this is significant, the researchers emphasize that reforestation alone should not be a substitute for worldwide pollution control efforts.

    “Countries have put a lot of effort into reducing mercury emissions, especially northern industrialized countries, and for very good reason. But 10 percent of the global anthropogenic source is substantial, and there is a potential for that to be even greater in the future. [Addressing these deforestation-related emissions] needs to be part of the solution,” says senior author Noelle Selin, a professor in IDSS and MIT’s Department of Earth, Atmospheric and Planetary Sciences.

    Feinberg and Selin are joined on the paper by co-authors Martin Jiskra, a former Swiss National Science Foundation Ambizione Fellow at the University of Basel; Pasquale Borrelli, a professor at Roma Tre University in Italy; and Jagannath Biswakarma, a postdoc at the Swiss Federal Institute of Aquatic Science and Technology. The paper appears today in Environmental Science and Technology.

    Modeling mercury

    Over the past few decades, scientists have generally focused on studying deforestation as a source of global carbon dioxide emissions. Mercury, a trace element, hasn’t received the same attention, partly because the terrestrial biosphere’s role in the global mercury cycle has only recently been better quantified.

    Plant leaves take up mercury from the atmosphere, in a similar way as they take up carbon dioxide. But unlike carbon dioxide, mercury doesn’t play an essential biological function for plants. Mercury largely stays within a leaf until it falls to the forest floor, where the mercury is absorbed by the soil.

    Mercury becomes a serious concern for humans if it ends up in water bodies, where it can become methylated by microorganisms. Methylmercury, a potent neurotoxin, can be taken up by fish and bioaccumulated through the food chain. This can lead to risky levels of methylmercury in the fish humans eat.

    “In soils, mercury is much more tightly bound than it would be if it were deposited in the ocean. The forests are doing a sort of ecosystem service, in that they are sequestering mercury for longer timescales,” says Feinberg, who is now a postdoc in the Blas Cabrera Institute of Physical Chemistry in Spain.

    In this way, forests reduce the amount of toxic methylmercury in oceans.

    Many studies of mercury focus on industrial sources, like burning fossil fuels, small-scale gold mining, and metal smelting. A global treaty, the 2013 Minamata Convention, calls on nations to reduce human-made emissions. However, it doesn’t directly consider impacts of deforestation.

    The researchers launched their study to fill in that missing piece.

    In past work, they had built a model to probe the role vegetation plays in mercury uptake. Using a series of land use change scenarios, they adjusted the model to quantify the role of deforestation.

    Evaluating emissions

    This chemical transport model tracks mercury from its emissions sources to where it is chemically transformed in the atmosphere and then ultimately to where it is deposited, mainly through rainfall or uptake into forest ecosystems.

    They divided the Earth into eight regions and performed simulations to calculate deforestation emissions factors for each, considering elements like type and density of vegetation, mercury content in soils, and historical land use.

    However, good data for some regions were hard to come by.

    They lacked measurements from tropical Africa or Southeast Asia — two areas that experience heavy deforestation. To get around this gap, they used simpler, offline models to simulate hundreds of scenarios, which helped them improve their estimations of potential uncertainties.

    They also developed a new formulation for mercury emissions from soil. This formulation captures the fact that deforestation reduces leaf area, which increases the amount of sunlight that hits the ground and accelerates the outgassing of mercury from soils.

    The model divides the world into grid squares, each of which is a few hundred square kilometers. By changing land surface and vegetation parameters in certain squares to represent deforestation and reforestation scenarios, the researchers can capture impacts on the mercury cycle.

    Overall, they found that about 200 tons of mercury are emitted to the atmosphere as the result of deforestation, or about 10 percent of total human-made emissions. But in tropical and sub-tropical countries, deforestation emissions represent a higher percentage of total emissions. For example, in Brazil deforestation emissions are 40 percent of total human-made emissions.

    In addition, people often light fires to prepare tropical forested areas for agricultural activities, which causes more emissions by releasing mercury stored by vegetation.

    “If deforestation was a country, it would be the second highest emitting country, after China, which emits around 500 tons of mercury a year,” Feinberg adds.

    And since the Minamata Convention is now addressing primary mercury emissions, scientists can expect deforestation to become a larger fraction of human-made emissions in the future.

    “Policies to protect forests or cut them down have unintended effects beyond their target. It is important to consider the fact that these are systems, and they involve human activities, and we need to understand them better in order to actually solve the problems that we know are out there,” Selin says.

    By providing this first estimate, the team hopes to inspire more research in this area.

    In the future, they want to incorporate more dynamic Earth system models into their analysis, which would enable them to interactively track mercury uptake and better model the timescale of vegetation regrowth.

    “This paper represents an important advance in our understanding of global mercury cycling by quantifying a pathway that has long been suggested but not yet quantified. Much of our research to date has focused on primary anthropogenic emissions — those directly resulting from human activity via coal combustion or mercury-gold amalgam burning in artisanal and small-scale gold mining,” says Jackie Gerson, an assistant professor in the Department of Earth and Environmental Sciences at Michigan State University, who was not involved with this research. “This research shows that deforestation can also result in substantial mercury emissions and needs to be considered both in terms of global mercury models and land management policies. It therefore has the potential to advance our field scientifically as well as to promote policies that reduce mercury emissions via deforestation.

    This work was funded, in part, by the U.S. National Science Foundation, the Swiss National Science Foundation, and Swiss Federal Institute of Aquatic Science and Technology. More

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    Letter to the MIT community: Announcing the Climate Project at MIT

    The following letter was sent to the MIT community today by President Sally Kornbluth.

    Dear members of the MIT community,

    At my inauguration, echoing a sentiment I heard everywhere on my campus listening tour, I called on the people of MIT to come together in new ways to marshal a bold, tenacious response to the run-away crisis of climate change.

    I write with an update on how we’re bringing this vision to life.

    This letter includes several significant announcements – including an accelerated search for faculty leaders and a very substantial commitment of MIT funds – so please read on.

    A Record of MIT Leadership

    Since the late Professor Jule Charney led a 1979 National Academy of Sciences report that foretold the likely risks of global warming, MIT researchers have made pioneering contributions in countless relevant fields. Today, more than 300 faculty, working with their students and research and teaching staff, are engaged in leading-edge work on climate issues. The Institute has also taken important steps to enhance climate education, expand public outreach on climate and decarbonize the campus.

    But – as the community told me loud and clear – this moment demands a different order of speed, ambition, focus and scale.

    The Climate Project at MIT

    After extensive consultation with more than 150 faculty and senior researchers across the Institute – and building on the strengths of Fast Forward: MIT’s Climate Action Plan for the Decade, issued in 2021 – Vice Provost Richard Lester has led us in framing a new approach: the Climate Project at MIT.  

    Representing a compelling new strategy for accelerated, university-led innovation, the Climate Project at MIT will focus our community’s talent and resources on solving critical climate problems with all possible speed – and will connect us with a range of partners to deliver those technological, behavioral and policy solutions to the world.

    As Richard explains in this MIT News 3Q, the Climate Project at MIT is still in its early stages; as it gains new leaders and new allies from academia, industry, philanthropy and government, it will continue to be shaped by their insight and expertise.

    For now, we begin with a new structure and strategy for organizing the work. The Climate Project at MIT will consist of three interlocking elements:

    The Climate Missions
    The Climate Frontier projects
    The Climate HQ

    To learn more about these components, I encourage you to read this summary of the plan (PDF). 

    Recruiting Leaders for the Six Climate Missions

    The central focus will be six Climate Missions – each constituting a cross-disciplinary Institute-wide problem-solving community focused on a strategic area of the climate challenge:

    Decarbonizing Energy and Industry
    Restoring the Atmosphere, Protecting the Land and Oceans
    Empowering Frontline Communities
    Building and Adapting Healthy, Resilient Cities
    Inventing New Policy Approaches
    Wild Cards

    We’re now recruiting an MIT faculty leader for each of these missions – on an accelerated timeline. We welcome any interested faculty member to apply to be a Climate Mission leader or to nominate a colleague. Please submit your CV and statement of interest at climatesearch@mit.edu by February 22.

    You can learn more about the role on the Climate Project’s preliminary webpage. All submissions will be treated as confidential.

    A New Leadership Role, a Search Committee – and Significant MIT Resources

    The Climate Project at MIT is gathering steam – and we will build its momentum with these three important steps.

    1. Vice President for Climate

    To match the prime importance of this work, we have created a new leadership role, reporting to me: Vice President for Climate (VPC). The VPC will oversee the Climate Project at MIT, take the lead on fundraising and implementation, and shape its strategic vision. We are opening the search now and welcome candidates from inside and outside MIT. You may submit your CV and statement of interest in the VPC role at climatesearch@mit.edu. A formal job description will be posted soon.

    2. Climate Search Advisory Committee

    To advise me in selecting the six mission leaders and the VPC, I have appointed the following faculty members to serve on the Climate Search Advisory Committee:

    Richard Lester, Chair
    Daron Acemoglu
    Yet-Ming Chiang
    Penny Chisholm
    Dava Newman
    Ron Rivest
    Susan Solomon
    John Sterman
    Larry Vale
    Rob van der Hilst
    Anne White

    3. $75 million in support from the Institute and MIT Sloan

    And finally: We will jumpstart the Climate Project at MIT with a commitment of $50 million in Institute resources – the largest direct investment the Institute has ever made in funding climate work, and just the beginning of a far more ambitious effort to raise the funds this extraordinary challenge demands. In addition, the Sloan School will contribute $25 million to endow a new climate policy center, to be formally announced in the coming days. Together, these funds will allow for early advances and express the seriousness of our intentions to potential partners around the world.

    *    *    *

    The Climate Project at MIT is ambitious, multifaceted and more complex than I could capture in a letter; I urge you to explore the summary of the plan (PDF) to see where you might fit. There will be a place for everyone, including all of our existing climate-involved DLCs. (And you might enjoy this brief video, which celebrates MIT’s distinctive gift for collaborative problem-solving on a grand scale.)

    At last spring’s inauguration, I said I hoped that, a decade hence, all of us at MIT could take pride in having “helped lead a powerful cross-sector coalition and placed big bets on big solutions, to dramatically accelerate progress against climate change.”

    With your creativity, support and drive, we have every reason to hope that the Climate Project at MIT can make that aspiration real.

    With enthusiasm and anticipation,

    Sally Kornbluth More

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    Illustrating India’s complex environmental crises

    Abhijit Banerjee, the Ford Foundation International Professor of Economics at MIT, and Sarnath Banerjee (no relation), an MIT Center for Art, Science, and Technology (CAST) visiting artist share a similar background, but have very different ways of thinking. Both were raised for a time in Kolkata before leaving India to pursue divergent careers, Abhijit as an economist who went on to win the 2019 Nobel Memorial Prize in Economic Sciences (an award he shares with MIT Professor Esther Duflo and Harvard University Professor Michael Kremer), and Sarnath as a visual artist and graphic novelist. 

    The two collaborated on a pair of short films, “The Land of Good Intentions” and “The Eternal Swamp,” that blend their expertise in a unique and captivating form. Each film addresses a particular environmental crisis facing present-day India by tracing its origins back through the centuries. The films are presented in a kind of lecture style, with Abhijit appearing as the narrator, unraveling historical details, as graphics by Sarnath visualize the story with an often wry and easy wit. The results apply logic and narrative coherence to problems with complex roots in the forces of nature, economics, and local culture. 

    “The Land of Good Intentions” explores the conditions and policies that led to mass protests by farmers, in Punjab and elsewhere, following the passage of farming legislation in September 2020. The film begins by providing historical context from multiple angles, including the significance of rice to regional culture, its growing conditions (which require a lot of water), the region’s climate (which produces very little), and previous government subsidies that led to its overproduction. The 2020 Farm Bills were intended to address rice overproduction and its consequences, including the depletion of Punjab’s groundwater supply, pollution from the burning of rice stalks, and a surplus going to waste. But farmers considered that they were being asked to shoulder the costs of a problem the government created. 

    “The arguments in the film don’t necessarily align with popular liberal arguments, but it gives subtler shape and layers to them,” Sarnath says. “That dialectical way of thinking is important to the liberal movement, which is driven by passion and a sense of justice. Abhijit is driven by factual analysis, which sometimes makes the argument more complex.”

    Their second film, “The Eternal Swamp,” addresses the crisis of flooding in Kolkata and its causes in the geographical and economic development of the city from the start. Because Kolkata was built on very wet land, and real estate has long been one of the only viable industries in the city, it has been developed without regard to proper drainage in a climate that produces more rainfall than it can handle. There is a pervading sense that Kolkata will eventually be entirely below water.

    “It was a good collaboration from the beginning,” Sarnath says of working with Abhijit on the CAST Visiting Artist project, a process which began just before Abhijit was awarded the Nobel Prize in 2019 and continued through the pandemic. “Both of us work on instinct, but the way he shapes an argument is very different from me,” Sarnath says. “My work does not follow a linear approach to telling a story; it’s fragmentary, driven by mood and emotion more than narrative, like composing a piece of music.”

    Since they first met at a literary conference years ago, Abhijit and Sarnath have been close friends and intellectual sparring partners. Though Sarnath is based in Berlin and Abhijit in Boston, the two often cross paths in different locales and have long, ambling discussions that traverse a wide array of topics. “We spend a lot of time walking together wherever we find ourselves, whether it’s down the Longfellow Bridge in Boston or through Delhi or Kolkata,” Sarnath says. The idea for this project was born out of such conversations, in response to pressing events in their home country. 

    Abhijit wrote a proposal to MIT CAST, and the questions they received through the process helped them further shape the project. “It’s important, when you have the luxury, just to spend time together. Thanks to MIT, we managed to do that across continents,” Sarnath says of their creative process. “It’s more than just telling a story; Abhijit unpacked what was in his head, and I drew and wrote a bit as well,” Sarnath says. And they worked with the editor and animator Niusha Ramzani, whom Sarnath says lent an Iranian aesthetic to the film’s animations. 

    As for the format of the films, they wanted to capture the sense of a serene Bengali afternoon, with Abhijit seated in his home in Kolkata speaking in a relaxed tone. “We wanted it to be a bit like a Royal Society lecture,” Sarnath says, somewhat like a TED Talk but more personable and intimate. The aim was to make their complicated subjects more easily comprehensible, through the language of Abhijit’s narration and with the help of visual metaphors. Still, they did not want to sacrifice complexity.

    “Economists are fabulists,” says Abhijit Banerjee. “We tell stories, simple stories, but that tends to get obscured in the telling, often because we like to be very careful about not overstating our case. Irony and the kind of playful humor that Sarnath brings to narration seemed to offer a different way to avoid being too emphatic, while allowing the story to be told in a way that it reaches a much larger audience. What is brilliant about Sarnath’s work is the play between reliable and the unreliable — the readers are happy to be misdirected because they know that it will ultimately lead them where they want to be. I was hoping we could bring a little of that into economics.” 

    “You have to emancipate yourself from any one definitive answer,” Sarnath Banerjee says, describing Abhijit’s expansive way of thinking, through which he follows multiple thought processes to their logical conclusions. The result allows for ambiguity and contradiction, though the pathways of thinking are clear. The films illustrate the situations facing farmers in Punjab and the waterlogged streets of Kolkata by tracing their roots and examining the history of cause and effect. The results provide clarity, but no simple answers.

    The process was an enriching one for both of them, the kind of advancement in understanding that can only come in dialogue. “With each collaboration, you learn, and learning to me is an artistic form,” Sarnath says. “We are always learning.” More

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    MADMEC winner creates “temporary tattoos” for T-shirts

    Have you ever gotten a free T-shirt at an event that you never wear? What about a music or sports-themed shirt you wear to one event and then lose interest in entirely? Such one-off T-shirts — and the waste and pollution associated with them — are an unfortunately common part of our society.

    But what if you could change the designs on shirts after each use? The winners of this year’s MADMEC competition developed biodegradable “temporary tattoos” for T-shirts to make one-wear clothing more sustainable.

    Members of the winning team, called Me-Shirts, got their inspiration from the MADMEC event itself, which ordinarily makes a different T-shirt each year.

    “If you think about all the textile waste that’s produced for all these shirts, it’s insane,” team member and PhD candidate Isabella Caruso said in the winning presentation. “The main markets we are trying to address are for one-time T-shirts and custom T-shirts.”

    The problem is a big one. According to the team, the custom T-shirt market is a $4.3 billion industry. That doesn’t include trends like fast fashion that contribute to the 17 million tons of textile waste produced each year.

    “Our proposed solution is a temporary shirt tattoo made from biodegradable, nontoxic materials,” Caruso explained. “We wanted designs that are fully removable through washing, so that you can wear your T-shirt for your one-time event and then get a nice white T-shirt back afterward.”

    The team’s scalable design process mixes three simple ingredients: potato starch, glycerin, and water. The design can be imprinted on the shirt temporarily through ironing.

    The Me-Shirt team, which earned $10,000 with the win, plans to continue exploring material combinations to make the design more flexible and easier for people to apply at home. Future iterations could allow users to decide if they want the design to stay on the shirt during washes based on the settings of the washing machine.

    Hosted by MIT’s Department of Materials Science and Engineering (DMSE), the competition was the culmination of team projects that began in the fall and included a series of design challenges throughout the semester. Each team received guidance, access to equipment and labs, and up to $1,000 in funding to build and test their prototypes.

    “The main goal is that they gained some confidence in their ability to design and build devices and platforms that are different from their normal experiences,” Mike Tarkanian, a senior lecturer in DMSE and coordinator of MADMEC, said at the event. “If it’s a departure from their normal research and coursework activities that’s a win, I think, to make them better engineers.”

    The second-place, $6,000 prize went to Alkalyne, which is creating a carbon-neutral polymer for petrochemical production. The company is developing approaches for using electricity and inorganic carbon to generate a high-energy hydrocarbon precursor. If developed using renewable energy, the approach could be used to achieve carbon negative petrochemical production.

    “A lot of our research, and a lot of the research around MIT in general, has to do with sustainability, so we wanted to try an angle that we think looks promising but doesn’t seem to be investigated enough,” PhD candidate Christopher Mallia explained.

    The third-place prize went to Microbeco, which is exploring the use of microbial fuel cells for continuous water quality monitoring. Microbes have been proposed as a way to detect and measure contaminants in water for decades, but the team believes the varying responses of microbes to different contaminants has limited the effectiveness of the approach.

    To overcome that problem, the team is working to isolate microbial strains that respond more regularly to specific contaminants.

    Overall, Tarkanian believes this year’s program was a success not only because of the final results presented at the competition, but because of the experience the students got along the way using equipment like laser cutters, 3D printers, and soldering irons. Many participants said they had never used that type of equipment before. They also said by working to build physical prototypes, the program helped make their coursework come to life.

    “It was a chance to try something new by applying my skills to a different environment,” PhD candidate Zachary Adams said. “I can see a lot of the concepts I learn in my classes through this work.” More