Civil and environmental engineering

Subterms

    Latest story

    113 Shares195 Views

    Minimizing the carbon footprint of bridges and other structures

    by

    Awed as a young child by the majesty of the Golden Gate Bridge in San Francisco, civil engineer and MIT Morningside Academy for Design (MAD) Fellow Zane Schemmer has retained his fascination with bridges: what they look like, why they work, and how they’re designed and built.He weighed the choice between architecture and engineering when heading off to college, but, motivated by the why and how of structural engineering, selected the latter. Now he incorporates design as an iterative process in the writing of algorithms that perfectly balance the forces involved in discrete portions of a structure to create an overall design that optimizes function, minimizes carbon footprint, and still produces a manufacturable result.While this may sound like an obvious goal in structural design, it’s not. It’s new. It’s a more holistic way of looking at the design process that can optimize even down to the materials, angles, and number of elements in the nodes or joints that connect the larger components of a building, bridge, tower, etc.According to Schemmer, there hasn’t been much progress on optimizing structural design to minimize embodied carbon, and the work that exists often results in designs that are “too complex to be built in real life,” he says. The embodied carbon of a structure is the total carbon dioxide emissions of its life cycle: from the extraction or manufacture of its materials to their transport and use and through the demolition of the structure and disposal of the materials. Schemmer, who works with Josephine V. Carstensen, the Gilbert W. Winslow Career Development Associate Professor of Civil and Environmental Engineering at MIT, is focusing on the portion of that cycle that runs through construction.In September, at the IASS 2024 symposium “Redefining the Art of Structural Design in Zurich,” Schemmer and Carstensen presented their work on Discrete Topology Optimization algorithms that are able to minimize the embodied carbon in a bridge or other structure by up to 20 percent. This comes through materials selection that considers not only a material’s appearance and its ability to get the job done, but also the ease of procurement, its proximity to the building site, and the carbon embodied in its manufacture and transport.“The real novelty of our algorithm is its ability to consider multiple materials in a highly constrained solution space to produce manufacturable designs with a user-specified force flow,” Schemmer says. “Real-life problems are complex and often have many constraints associated with them. In traditional formulations, it can be difficult to have a long list of complicated constraints. Our goal is to incorporate these constraints to make it easier to take our designs out of the computer and create them in real life.”Take, for instance, a steel tower, which could be a “super lightweight, efficient design solution,” Schemmer explains. Because steel is so strong, you don’t need as much of it compared to concrete or timber to build a big building. But steel is also very carbon-intensive to produce and transport. Shipping it across the country or especially from a different continent can sharply increase its embodied carbon price tag. Schemmer’s topology optimization will replace some of the steel with timber elements or decrease the amount of steel in other elements to create a hybrid structure that will function effectively and minimize the carbon footprint. “This is why using the same steel in two different parts of the world can lead to two different optimized designs,” he explains.Schemmer, who grew up in the mountains of Utah, earned a BS and MS in civil and environmental engineering from University of California at Berkeley, where his graduate work focused on seismic design. He describes that education as providing a “very traditional, super-strong engineering background that tackled some of the toughest engineering problems,” along with knowledge of structural engineering’s traditions and current methods.But at MIT, he says, a lot of the work he sees “looks at removing the constraints of current societal conventions of doing things, and asks how could we do things if it was in a more ideal form; what are we looking at then? Which I think is really cool,” he says. “But I think sometimes too, there’s a jump between the most-perfect version of something and where we are now, that there needs to be a bridge between those two. And I feel like my education helps me see that bridge.”The bridge he’s referring to is the topology optimization algorithms that make good designs better in terms of decreased global warming potential.“That’s where the optimization algorithm comes in,” Schemmer says. “In contrast to a standard structure designed in the past, the algorithm can take the same design space and come up with a much more efficient material usage that still meets all the structural requirements, be up to code, and have everything we want from a safety standpoint.”That’s also where the MAD Design Fellowship comes in. The program provides yearlong fellowships with full financial support to graduate students from all across the Institute who network with each other, with the MAD faculty, and with outside speakers who use design in new ways in a surprising variety of fields. This helps the fellows gain a better understanding of how to use iterative design in their own work.“Usually people think of their own work like, ‘Oh, I had this background. I’ve been looking at this one way for a very long time.’ And when you look at it from an outside perspective, I think it opens your mind to be like, ‘Oh my God. I never would have thought about doing this that way. Maybe I should try that.’ And then we can move to new ideas, new inspiration for better work,” Schemmer says.He chose civil and structural engineering over architecture some seven years ago, but says that “100 years ago, I don’t think architecture and structural engineering were two separate professions. I think there was an understanding of how things looked and how things worked, and it was merged together. Maybe from an efficiency standpoint, it’s better to have things done separately. But I think there’s something to be said for having knowledge about how the whole system works, potentially more intermingling between the free-form architectural design and the mathematical design of a civil engineer. Merging it back together, I think, has a lot of benefits.”Which brings us back to the Golden Gate Bridge, Schemmer’s longtime favorite. You can still hear that excited 3-year-old in his voice when he talks about it.“It’s so iconic,” he says. “It’s connecting these two spits of land that just rise straight up out of the ocean. There’s this fog that comes in and out a lot of days. It’s a really magical place, from the size of the cable strands and everything. It’s just, ‘Wow.’ People built this over 100 years ago, before the existence of a lot of the computational tools that we have now. So, all the math, everything in the design, was all done by hand and from the mind. Nothing was computerized, which I think is crazy to think about.”As Schemmer continues work on his doctoral degree at MIT, the MAD fellowship will expose him to many more awe-inspiring ideas in other fields, leading him to incorporate some of these in some way with his engineering knowledge to design better ways of building bridges and other structures. More

    More stories

    • 125 Shares119 Views

      in Environment

      An abundant phytoplankton feeds a global network of marine microbes

      by

      One of the hardest-working organisms in the ocean is the tiny, emerald-tinged Prochlorococcus marinus. These single-celled “picoplankton,” which are smaller than a human red blood cell, can be found in staggering numbers throughout the ocean’s surface waters, making Prochlorococcus the most abundant photosynthesizing organism on the planet. (Collectively, Prochlorococcus fix as much carbon as all the crops on land.) Scientists continue to find new ways that the little green microbe is involved in the ocean’s cycling and storage of carbon.Now, MIT scientists have discovered a new ocean-regulating ability in the small but mighty microbes: cross-feeding of DNA building blocks. In a study appearing today in Science Advances, the team reports that Prochlorococcus shed these extra compounds into their surroundings, where they are then “cross-fed,” or taken up by other ocean organisms, either as nutrients, energy, or for regulating metabolism. Prochlorococcus’ rejects, then, are other microbes’ resources.What’s more, this cross-feeding occurs on a regular cycle: Prochlorococcus tend to shed their molecular baggage at night, when enterprising microbes quickly consume the cast-offs. For a microbe called SAR11, the most abundant bacteria in the ocean, the researchers found that the nighttime snack acts as a relaxant of sorts, forcing the bacteria to slow down their metabolism and effectively recharge for the next day.Through this cross-feeding interaction, Prochlorococcus could be helping many microbial communities to grow sustainably, simply by giving away what it doesn’t need. And they’re doing so in a way that could set the daily rhythms of microbes around the world.“The relationship between the two most abundant groups of microbes in ocean ecosystems has intrigued oceanographers for years,” says co-author and MIT Institute Professor Sallie “Penny” Chisholm, who played a role in the discovery of Prochlorococcus in 1986. “Now we have a glimpse of the finely tuned choreography that contributes to their growth and stability across vast regions of the oceans.”Given that Prochlorococcus and SAR11 suffuse the surface oceans, the team suspects that the exchange of molecules from one to the other could amount to one of the major cross-feeding relationships in the ocean, making it an important regulator of the ocean carbon cycle.“By looking at the details and diversity of cross-feeding processes, we can start to unearth important forces that are shaping the carbon cycle,” says the study’s lead author, Rogier Braakman, a research scientist in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).Other MIT co-authors include Brandon Satinsky, Tyler O’Keefe, Shane Hogle, Jamie Becker, Robert Li, Keven Dooley, and Aldo Arellano, along with Krista Longnecker, Melissa Soule, and Elizabeth Kujawinski of Woods Hole Oceanographic Institution (WHOI).Spotting castawaysCross-feeding occurs throughout the microbial world, though the process has mainly been studied in close-knit communities. In the human gut, for instance, microbes are in close proximity and can easily exchange and benefit from shared resources.By comparison, Prochlorococcus are free-floating microbes that are regularly tossed and mixed through the ocean’s surface layers. While scientists assume that the plankton are involved in some amount of cross-feeding, exactly how this occurs, and who would benefit, have historically been challenging to probe; any stuff that Prochlorococcus cast away would have vanishingly low concentrations,and be exceedingly difficult to measure.But in work published in 2023, Braakman teamed up with scientists at WHOI, who pioneered ways to measure small organic compounds in seawater. In the lab, they grew various strains of Prochlorococcus under different conditions and characterized what the microbes released. They found that among the major “exudants,” or released molecules, were purines and pyridines, which are molecular building blocks of DNA. The molecules also happen to be nitrogen-rich — a fact that puzzled the team. Prochlorococcus are mainly found in ocean regions that are low in nitrogen, so it was assumed they’d want to retain any and all nitrogen-containing compounds they can. Why, then, were they instead throwing such compounds away?Global symphonyIn their new study, the researchers took a deep dive into the details of Prochlorococcus’ cross-feeding and how it influences various types of ocean microbes.They set out to study how Prochlorococcus use purine and pyridine in the first place, before expelling the compounds into their surroundings. They compared published genomes of the microbes, looking for genes that encode purine and pyridine metabolism. Tracing the genes forward through the genomes, the team found that once the compounds are produced, they are used to make DNA and replicate the microbes’ genome. Any leftover purine and pyridine is recycled and used again, though a fraction of the stuff is ultimately released into the environment. Prochlorococcus appear to make the most of the compounds, then cast off what they can’t.The team also looked to gene expression data and found that genes involved in recycling purine and pyrimidine peak several hours after the recognized peak in genome replication that occurs at dusk. The question then was: What could be benefiting from this nightly shedding?For this, the team looked at the genomes of more than 300 heterotrophic microbes — organisms that consume organic carbon rather than making it themselves through photosynthesis. They suspected that such carbon-feeders could be likely consumers of Prochlorococcus’ organic rejects. They found most of the heterotrophs contained genes that take up either purine or pyridine, or in some cases, both, suggesting microbes have evolved along different paths in terms of how they cross-feed.The group zeroed in on one purine-preferring microbe, SAR11, as it is the most abundant heterotrophic microbe in the ocean. When they then compared the genes across different strains of SAR11, they found that various types use purines for different purposes, from simply taking them up and using them intact to breaking them down for their energy, carbon, or nitrogen. What could explain the diversity in how the microbes were using Prochlorococcus’ cast-offs?It turns out the local environment plays a big role. Braakman and his collaborators performed a metagenome analysis in which they compared the collectively sequenced genomes of all microbes in over 600 seawater samples from around the world, focusing on SAR11 bacteria. Metagenome sequences were collected alongside measurements of various environmental conditions and geographic locations in which they are found. This analysis showed that the bacteria gobble up purine for its nitrogen when the nitrogen in seawater is low, and for its carbon or energy when nitrogen is in surplus — revealing the selective pressures shaping these communities in different ocean regimes.“The work here suggests that microbes in the ocean have developed relationships that advance their growth potential in ways we don’t expect,” says co-author Kujawinski.Finally, the team carried out a simple experiment in the lab, to see if they could directly observe a mechanism by which purine acts on SAR11. They grew the bacteria in cultures, exposed them to various concentrations of purine, and unexpectedly found it causes them to slow down their normal metabolic activities and even growth. However, when the researchers put these same cells under environmentally stressful conditions, they continued growing strong and healthy cells, as if the metabolic pausing by purines helped prime them for growth, thereby avoiding the effects of the stress.“When you think about the ocean, where you see this daily pulse of purines being released by Prochlorococcus, this provides a daily inhibition signal that could be causing a pause in SAR11 metabolism, so that the next day when the sun comes out, they are primed and ready,” Braakman says. “So we think Prochlorococcus is acting as a conductor in the daily symphony of ocean metabolism, and cross-feeding is creating a global synchronization among all these microbial cells.”This work was supported, in part, by the Simons Foundation and the National Science Foundation. More

    • 100 Shares129 Views

      in Environment

      Enabling a circular economy in the built environment

      by

      The amount of waste generated by the construction sector underscores an urgent need for embracing circularity — a sustainable model that aims to minimize waste and maximize material efficiency through recovery and reuse — in the built environment: 600 million tons of construction and demolition waste was produced in the United States alone in 2018, with 820 million tons reported in the European Union, and an excess of 2 billion tons annually in China.This significant resource loss embedded in our current industrial ecosystem marks a linear economy that operates on a “take-make-dispose” model of construction; in contrast, the “make-use-reuse” approach of a circular economy offers an important opportunity to reduce environmental impacts.A team of MIT researchers has begun to assess what may be needed to spur widespread circular transition within the built environment in a new open-access study that aims to understand stakeholders’ current perceptions of circularity and quantify their willingness to pay.“This paper acts as an initial endeavor into understanding what the industry may be motivated by, and how integration of stakeholder motivations could lead to greater adoption,” says lead author Juliana Berglund-Brown, PhD student in the Department of Architecture at MIT.Considering stakeholders’ perceptionsThree different stakeholder groups from North America, Europe, and Asia — material suppliers, design and construction teams, and real estate developers — were surveyed by the research team that also comprises Akrisht Pandey ’23; Fabio Duarte, associate director of the MIT Senseable City Lab; Raquel Ganitsky, fellow in the Sustainable Real Estate Development Action Program; Randolph Kirchain, co-director of MIT Concrete Sustainability Hub; and Siqi Zheng, the STL Champion Professor of Urban and Real Estate Sustainability at Department of Urban Studies and Planning.Despite growing awareness of reuse practice among construction industry stakeholders, circular practices have yet to be implemented at scale — attributable to many factors that influence the intersection of construction needs with government regulations and the economic interests of real estate developers.The study notes that perceived barriers to circular adoption differ based on industry role, with lack of both client interest and standardized structural assessment methods identified as the primary concern of design and construction teams, while the largest deterrents for material suppliers are logistics complexity, and supply uncertainty. Real estate developers, on the other hand, are chiefly concerned with higher costs and structural assessment. Yet encouragingly, respondents expressed willingness to absorb higher costs, with developers indicating readiness to pay an average of 9.6 percent higher construction costs for a minimum 52.9 percent reduction in embodied carbon — and all stakeholders highly favor the potential of incentives like tax exemptions to aid with cost premiums.Next steps to encourage circularityThe findings highlight the need for further conversation between design teams and developers, as well as for additional exploration into potential solutions to practical challenges. “The thing about circularity is that there is opportunity for a lot of value creation, and subsequently profit,” says Berglund-Brown. “If people are motivated by cost, let’s provide a cost incentive, or establish strategies that have one.”When it comes to motivating reasons to adopt circularity practices, the study also found trends emerging by industry role. Future net-zero goals influence developers as well as design and construction teams, with government regulation the third-most frequently named reason across all respondent types.“The construction industry needs a market driver to embrace circularity,” says Berglund-Brown, “Be it carrots or sticks, stakeholders require incentives for adoption.”The effect of policy to motivate change cannot be understated, with major strides being made in low operational carbon building design after policy restricting emissions was introduced, such as Local Law 97 in New York City and the Building Emissions Reduction and Disclosure Ordinance in Boston. These pieces of policy, and their results, can serve as models for embodied carbon reduction policy elsewhere.Berglund-Brown suggests that municipalities might initiate ordinances requiring buildings to be deconstructed, which would allow components to be reused, curbing demolition methods that result in waste rather than salvage. Top-down ordinances could be one way to trigger a supply chain shift toward reprocessing building materials that are typically deemed “end-of-life.”The study also identifies other challenges to the implementation of circularity at scale, including risk associated with how to reuse materials in new buildings, and disrupting status quo design practices.“Understanding the best way to motivate transition despite uncertainty is where our work comes in,” says Berglund-Brown. “Beyond that, researchers can continue to do a lot to alleviate risk — like developing standards for reuse.”Innovations that challenge the status quoDisrupting the status quo is not unusual for MIT researchers; other visionary work in construction circularity pioneered at MIT includes “a smart kit of parts” called Pixelframe. This system for modular concrete reuse allows building elements to be disassembled and rebuilt several times, aiding deconstruction and reuse while maintaining material efficiency and versatility.Developed by MIT Climate and Sustainability Consortium Associate Director Caitlin Mueller’s research team, Pixelframe is designed to accommodate a wide range of applications from housing to warehouses, with each piece of interlocking precast concrete modules, called Pixels, assigned a material passport to enable tracking through its many life cycles.Mueller’s work demonstrates that circularity can work technically and logistically at the scale of the built environment — by designing specifically for disassembly, configuration, versatility, and upfront carbon and cost efficiency.“This can be built today. This is building code-compliant today,” said Mueller of Pixelframe in a keynote speech at the recent MCSC Annual Symposium, which saw industry representatives and members of the MIT community coming together to discuss scalable solutions to climate and sustainability problems. “We currently have the potential for high-impact carbon reduction as a compelling alternative to the business-as-usual construction methods we are used to.”Pixelframe was recently awarded a grant by the Massachusetts Clean Energy Center (MassCEC) to pursue commercialization, an important next step toward integrating innovations like this into a circular economy in practice. “It’s MassCEC’s job to make sure that these climate leaders have the resources they need to turn their technologies into successful businesses that make a difference around the world,” said MassCEC CEO Emily Reichart, in a press release.Additional support for circular innovation has emerged thanks to a historic piece of climate legislation from the Biden administration. The Environmental Protection Agency recently awarded a federal grant on the topic of advancing steel reuse to Berglund-Brown — whose PhD thesis focuses on scaling the reuse of structural heavy-section steel — and John Ochsendorf, the Class of 1942 Professor of Civil and Environmental Engineering and Architecture at MIT.“There is a lot of exciting upcoming work on this topic,” says Berglund-Brown. “To any practitioners reading this who are interested in getting involved — please reach out.”The study is supported in part by the MIT Climate and Sustainability Consortium. More

    • 188 Shares119 Views

      in Energy

      So you want to build a solar or wind farm? Here’s how to decide where.

      by

      Deciding where to build new solar or wind installations is often left up to individual developers or utilities, with limited overall coordination. But a new study shows that regional-level planning using fine-grained weather data, information about energy use, and energy system modeling can make a big difference in the design of such renewable power installations. This also leads to more efficient and economically viable operations.The findings show the benefits of coordinating the siting of solar farms, wind farms, and storage systems, taking into account local and temporal variations in wind, sunlight, and energy demand to maximize the utilization of renewable resources. This approach can reduce the need for sizable investments in storage, and thus the total system cost, while maximizing availability of clean power when it’s needed, the researchers found.The study, appearing today in the journal Cell Reports Sustainability, was co-authored by Liying Qiu and Rahman Khorramfar, postdocs in MIT’s Department of Civil and Environmental Engineering, and professors Saurabh Amin and Michael Howland.Qiu, the lead author, says that with the team’s new approach, “we can harness the resource complementarity, which means that renewable resources of different types, such as wind and solar, or different locations can compensate for each other in time and space. This potential for spatial complementarity to improve system design has not been emphasized and quantified in existing large-scale planning.”Such complementarity will become ever more important as variable renewable energy sources account for a greater proportion of power entering the grid, she says. By coordinating the peaks and valleys of production and demand more smoothly, she says, “we are actually trying to use the natural variability itself to address the variability.”Typically, in planning large-scale renewable energy installations, Qiu says, “some work on a country level, for example saying that 30 percent of energy should be wind and 20 percent solar. That’s very general.” For this study, the team looked at both weather data and energy system planning modeling on a scale of less than 10-kilometer (about 6-mile) resolution. “It’s a way of determining where should we, exactly, build each renewable energy plant, rather than just saying this city should have this many wind or solar farms,” she explains.To compile their data and enable high-resolution planning, the researchers relied on a variety of sources that had not previously been integrated. They used high-resolution meteorological data from the National Renewable Energy Laboratory, which is publicly available at 2-kilometer resolution but rarely used in a planning model at such a fine scale. These data were combined with an energy system model they developed to optimize siting at a sub-10-kilometer resolution. To get a sense of how the fine-scale data and model made a difference in different regions, they focused on three U.S. regions — New England, Texas, and California — analyzing up to 138,271 possible siting locations simultaneously for a single region.By comparing the results of siting based on a typical method vs. their high-resolution approach, the team showed that “resource complementarity really helps us reduce the system cost by aligning renewable power generation with demand,” which should translate directly to real-world decision-making, Qiu says. “If an individual developer wants to build a wind or solar farm and just goes to where there is the most wind or solar resource on average, it may not necessarily guarantee the best fit into a decarbonized energy system.”That’s because of the complex interactions between production and demand for electricity, as both vary hour by hour, and month by month as seasons change. “What we are trying to do is minimize the difference between the energy supply and demand rather than simply supplying as much renewable energy as possible,” Qiu says. “Sometimes your generation cannot be utilized by the system, while at other times, you don’t have enough to match the demand.”In New England, for example, the new analysis shows there should be more wind farms in locations where there is a strong wind resource during the night, when solar energy is unavailable. Some locations tend to be windier at night, while others tend to have more wind during the day.These insights were revealed through the integration of high-resolution weather data and energy system optimization used by the researchers. When planning with lower resolution weather data, which was generated at a 30-kilometer resolution globally and is more commonly used in energy system planning, there was much less complementarity among renewable power plants. Consequently, the total system cost was much higher. The complementarity between wind and solar farms was enhanced by the high-resolution modeling due to improved representation of renewable resource variability.The researchers say their framework is very flexible and can be easily adapted to any region to account for the local geophysical and other conditions. In Texas, for example, peak winds in the west occur in the morning, while along the south coast they occur in the afternoon, so the two naturally complement each other.Khorramfar says that this work “highlights the importance of data-driven decision making in energy planning.” The work shows that using such high-resolution data coupled with carefully formulated energy planning model “can drive the system cost down, and ultimately offer more cost-effective pathways for energy transition.”One thing that was surprising about the findings, says Amin, who is a principal investigator in the MIT Laboratory of Information and Data Systems, is how significant the gains were from analyzing relatively short-term variations in inputs and outputs that take place in a 24-hour period. “The kind of cost-saving potential by trying to harness complementarity within a day was not something that one would have expected before this study,” he says.In addition, Amin says, it was also surprising how much this kind of modeling could reduce the need for storage as part of these energy systems. “This study shows that there is actually a hidden cost-saving potential in exploiting local patterns in weather, that can result in a monetary reduction in storage cost.”The system-level analysis and planning suggested by this study, Howland says, “changes how we think about where we site renewable power plants and how we design those renewable plants, so that they maximally serve the energy grid. It has to go beyond just driving down the cost of energy of individual wind or solar farms. And these new insights can only be realized if we continue collaborating across traditional research boundaries, by integrating expertise in fluid dynamics, atmospheric science, and energy engineering.”The research was supported by the MIT Climate and Sustainability Consortium and MIT Climate Grand Challenges. More

    • 75 Shares179 Views

      in Environment

      Q&A: Transforming research through global collaborations

      by

      The MIT Global Seed Funds (GSF) program fosters global research collaborations with MIT faculty and their peers abroad — creating partnerships that tackle complex global issues, from climate change to health-care challenges and beyond. Administered by the MIT Center for International Studies (CIS), the GSF program has awarded more than $26 million to over 1,200 faculty research projects since its inception in 2008. Through its unique funding structure — comprising a general fund for unrestricted geographical use and several specific funds within individual countries, regions, and universities — GSF supports a wide range of projects. The current call for proposals from MIT faculty and researchers with principal investigator status is open until Dec. 10. CIS recently sat down with faculty recipients Josephine Carstensen and David McGee to discuss the value and impact GSF added to their research. Carstensen, the Gilbert W. Winslow Career Development Associate Professor of Civil and Environmental Engineering, generates computational designs for large-scale structures with the intent of designing novel low-carbon solutions. McGee, the William R. Kenan, Jr. Professor in the Department of Earth, Atmospheric and Planetary Sciences (EAPS), reconstructs the patterns, pace, and magnitudes of past hydro-climate changes.Q: How did the Global Seed Funds program connect you with global partnerships related to your research?Carstensen: One of the projects my lab is working on is to unlock the potential of complex cast-glass structures. Through our GSF partnership with researchers at TUDelft (Netherlands), my group was able to leverage our expertise in generative design algorithms alongside the TUDelft team, who are experts in the physical casting and fabrication of glass structures. Our initial connection to TUDelft was actually through one of my graduate students who was at a conference and met TUDelft researchers. He was inspired by their work and felt there could be synergy between our labs. The question then became: How do we connect with TUDelft? And that was what led us to the Global Seed Funds program. McGee: Our research is based in fieldwork conducted in partnership with experts who have a rich understanding of local environments. These locations range from lake basins in Chile and Argentina to caves in northern Mexico, Vietnam, and Madagascar. GSF has been invaluable for helping foster partnerships with collaborators and universities in these different locations, enabling the pilot work and relationship-building necessary to establish longer-term, externally funded projects.Q: Tell us more about your GSF-funded work.Carstensen: In my research group at MIT, we live mainly in a computational regime, and we do very little proof-of-concept testing. To that point, we do not even have the facilities nor experience to physically build large-scale structures, or even specialized structures. GSF has enabled us to connect with the researchers at TUDelft who do much more experimental testing than we do. Being able to work with the experts at TUDelft within their physical realm provided valuable insights into their way of approaching problems. And, likewise, the researchers at TUDelft benefited from our expertise. It has been fruitful in ways we couldn’t have imagined within our lab at MIT.McGee: The collaborative work supported by the GSF has focused on reconstructing how past climate changes impacted rainfall patterns around the world, using natural archives like lake sediments and cave formations. One particularly successful project has been our work in caves in northeastern Mexico, which has been conducted in partnership with researchers from the National Autonomous University of Mexico (UNAM) and a local caving group. This project has involved several MIT undergraduate and graduate students, sponsored a research symposium in Mexico City, and helped us obtain funding from the National Science Foundation for a longer-term project.Q: You both mentioned the involvement of your graduate students. How exactly has the GSF augmented the research experience of your students?Carstensen: The collaboration has especially benefited the graduate students from both the MIT and TUDelft teams. The opportunity presented through this project to engage in research at an international peer institution has been extremely beneficial for their academic growth and maturity. It has facilitated training in new and complementary technical areas that they would not have had otherwise and allowed them to engage with leading world experts. An example of this aspect of the project’s success is that the collaboration has inspired one of my graduate students to actively pursue postdoc opportunities in Europe (including at TU Delft) after his graduation.McGee: MIT students have traveled to caves in northeastern Mexico and to lake basins in northern Chile to conduct fieldwork and build connections with local collaborators. Samples enabled by GSF-supported projects became the focus of two graduate students’ PhD theses, two EAPS undergraduate senior theses, and multiple UROP [Undergraduate Research Opportunity Program] projects.Q: Were there any unexpected benefits to the work funded by GSF?Carstensen: The success of this project would not have been possible without this specific international collaboration. Both the Delft and MIT teams bring highly different essential expertise that has been necessary for the successful project outcome. It allowed both the Delft and MIT teams to gain an in-depth understanding of the expertise areas and resources of the other collaborators. Both teams have been deeply inspired. This partnership has fueled conversations about potential future projects and provided multiple outcomes, including a plan to publish two journal papers on the project outcome. The first invited publication is being finalized now.McGee: GSF’s focus on reciprocal exchange has enabled external collaborators to spend time at MIT, sharing their work and exchanging ideas. Other funding is often focused on sending MIT researchers and students out, but GSF has helped us bring collaborators here, making the relationship more equal. A GSF-supported visit by Argentinian researchers last year made it possible for them to interact not just with my group, but with students and faculty across EAPS. More

    • 150 Shares139 Views

      in Environment

      Admir Masic: Using lessons from the past to build a better future

      by

      As a teenager living in a small village in what was then Yugoslavia, Admir Masic witnessed the collapse of his home country and the outbreak of the Bosnian war. When his childhood home was destroyed by a tank, his family was forced to flee the violence, leaving their remaining possessions to enter a refugee camp in northern Croatia.It was in Croatia that Masic found what he calls his “magic.”“Chemistry really forcefully entered my life,” recalls Masic, who is now an associate professor in MIT’s Department of Civil and Environmental Engineering. “I’d leave school to go back to my refugee camp, and you could either play ping-pong or do chemistry homework, so I did a lot of homework, and I began to focus on the subject.”Masic has never let go of his magic. Long after chemistry led him out of Croatia, he’s come to understand that the past holds crucial lessons for building a better future. That’s why he started the MIT Refugee Action Hub (now MIT Emerging Talent) to provide educational opportunities to students displaced by war. It’s also what led him to study ancient materials, whose secrets he believes have potential to solve some of the modern world’s most pressing problems.“We’re leading this concept of paleo-inspired design: that there are some ideas behind these ancient materials that are useful today,” Masic says. “We should think of these materials as a source of valuable information that we can try to translate to today. These concepts have the potential to revolutionize how we think about these materials.”One key research focus for Masic is cement. His lab is working on ways to transform the ubiquitous material into a carbon sink, a medium for energy storage, and more. Part of that work involves studying ancient Roman concrete, whose self-healing properties he has helped to illuminate.At the core of each of Masic’s research endeavors is a desire to translate a better understanding of materials into improvements in how we make things around the world.“Roman concrete to me is fascinating: It’s still standing after all this time and constantly repairing,” Masic says. “It’s clear there’s something special about this material, so what is it? Can we translate part of it into modern analogues? That’s what I love about MIT. We are put in a position to do cutting-edge research and then quickly translate that research into the real world. Impact for me is everything.”Finding a purposeMasic’s family fled to Croatia in 1992, just as he was set to begin high school. Despite excellent grades, Masic was told Bosnian refugees couldn’t enroll in the local school. It was only after a school psychologist advocated for Masic that he was allowed to sit in on classes as a nonmatriculating student.Masic did his best to be a ghost in the back of classrooms, silently absorbing everything he could. But in one subject he stood out. Within six months of joining the school, in January of 1993, a teacher suggested Masic compete in a local chemistry competition.“It was kind of the Olympiads of chemistry, and I won,” Masic recalls. “I literally floated onto the stage. It was this ‘Aha’ moment. I thought, ‘Oh my god, I’m good at chemistry!’”In 1994, Masic’s parents immigrated to Germany in search of a better life, but he decided to stay behind to finish high school, moving into a friend’s basement and receiving food and support from local families as well as a group of volunteers from Italy.“I just knew I had to stay,” Masic says. “With all the highs and lows of life to that point, I knew I had this talent and I had to make the most of it. I realized early on that knowledge was the one thing no one could take away from me.”Masic continued competing in chemistry competitions — and continued winning. Eventually, after a change to a national law, the high school he was attending agreed to give him a diploma. With the help of the Italian volunteers, he moved to Italy to attend the University of Turin, where he entered a five-year joint program that earned him a master’s degree in inorganic chemistry. Masic stayed at the university for his PhD, where he studied parchment, a writing material that’s been used for centuries to record some of humanity’s most sacred texts.With a classmate, Masic started a company that helped restore ancient documents. The work took him to Germany to work on a project studying the Dead Sea Scrolls, a set of manuscripts that date as far back as the third century BCE. In 2008, Masic joined the Max Planck Institute in Germany, where he also began to work with biological materials, studying water’s interaction with collagen at the nanoscale.Through that work, Masic became an expert in Raman spectroscopy, a type of chemical imaging that uses lasers to record the vibrations of molecules without leaving a trace, which he still uses to characterize materials.“Raman became a tool for me to contribute in the field of biological materials and bioinspired materials,” Masic says. “At the same time, I became the ‘Raman guy.’ It was a remarkable period for me professionally, as these tools provided unparalleled information and I published a lot of papers.”After seven years at Max Planck, Masic joined the Department of Civil and Environmental Engineering (CEE) at MIT.“At MIT, I felt I could truly be myself and define the research I wanted to do,” Masic says. “Especially in CEE, I could connect my work in heritage science and this tool, Raman spectroscopy, to tackle our society’s big challenges.”From labs to the worldRaman spectroscopy is a relatively new approach to studying cement, a material that contributes significantly to carbon dioxide emissions worldwide. At MIT, Masic has explored ways cement could be used to store carbon dioxide and act as an energy-storing supercapacitor. He has also solved ancient mysteries about the lasting strength of ancient Roman concrete, with lessons for the $400 billion cement industry today.“We really don’t think we should replace ordinary Portland cement completely, because it’s an extraordinary material that everyone knows how to work with, and industry produces so much of it. We need to introduce new functionalities into our concrete that will compensate for cement’s sustainability issues through avoided emissions,” Masic explains. “The concept we call ‘multifunctional concrete’ was inspired by our work with biological materials. Bones, for instance, sacrifice mechanical performance to be able to do things like self-healing and energy storage. That’s how you should imagine construction over next 10 years or 20 years. There could be concrete columns and walls that primarily offer support but also do things like store energy and continuously repair themselves.”Masic’s work across academia and industry allows him to apply his multifunctional concrete research at scale. He serves as a co-director of the MIT ec3 hub, a principal investigator within MIT Concrete Sustainability Hub, and a co-founder and advisor at the technology development company DMAT.“It’s great to be at the forefront of sustainability but also to be directly interacting with key industry players that can change the world,” Masic says. “What I appreciate about MIT is how you can engage in fundamental science and engineering while also translating that work into practical applications. The CSHub and ec3 hub are great examples of this. Industry is eager for us to develop solutions that they can help support.”And Masic will never forget where he came from. He now lives in Somerville, Massachusetts, with his wife Emina, a fellow former refugee, and their son, Benjamin, and the family shares a deep commitment to supporting displaced and underserved communities. Seven years ago, Masic founded the MIT Refugee Action Hub (ReACT), which provides computer and data science education programs for refugees and displaced communities. Today thousands of refugees apply to the program every year, and graduates have gone on to successful careers at places like Microsoft and Meta. The ReACT program was absorbed by MIT’s Emerging Talent program earlier this year to further its reach.“It’s really a life-changing experience for them,” Masic says. “It’s an amazing opportunity for MIT to nurture talented refugees around the world through this simple certification program. The more people we can involve, the more impact we will have on the lives of these truly underserved communities.” More

    • 88 Shares149 Views

      in Environment

      Making agriculture more resilient to climate change

      by

      As Earth’s temperature rises, agricultural practices will need to adapt. Droughts will likely become more frequent, and some land may no longer be arable. On top of that is the challenge of feeding an ever-growing population without expanding the production of fertilizer and other agrochemicals, which have a large carbon footprint that is contributing to the overall warming of the planet.Researchers across MIT are taking on these agricultural challenges from a variety of angles, from engineering plants that sound an alarm when they’re under stress to making seeds more resilient to drought. These types of technologies, and more yet to be devised, will be essential to feed the world’s population as the climate changes.“After water, the first thing we need is food. In terms of priority, there is water, food, and then everything else. As we are trying to find new strategies to support a world of 10 billion people, it will require us to invent new ways of making food,” says Benedetto Marelli, an associate professor of civil and environmental engineering at MIT.Marelli is the director of one of the six missions of the recently launched Climate Project at MIT, which focus on research areas such as decarbonizing industry and building resilient cities. Marelli directs the Wild Cards mission, which aims to identify unconventional solutions that are high-risk and high-reward.Drawing on expertise from a breadth of fields, MIT is well-positioned to tackle the challenges posed by climate change, Marelli says. “Bringing together our strengths across disciplines, including engineering, processing at scale, biological engineering, and infrastructure engineering, along with humanities, science, and economics, presents a great opportunity.”Protecting seeds from droughtMarelli, who began his career as a biomedical engineer working on regenerative medicine, is now developing ways to boost crop yields by helping seeds to survive and germinate during drought conditions, or in soil that has been depleted of nutrients. To achieve that, he has devised seed coatings, based on silk and other polymers, that can envelop and nourish seeds during the critical germination process.

      A new seed-coating process could facilitate agriculture on marginal arid lands by enabling the seeds to retain any available water.

      In healthy soil, plants have access to nitrogen, phosphates, and other nutrients that they need, many of which are supplied by microbes that live in the soil. However, in soil that has suffered from drought or overfarming, these nutrients are lacking. Marelli’s idea was to coat the seeds with a polymer that can be embedded with plant-growth-promoting bacteria that “fix” nitrogen by absorbing it from the air and making it available to plants. The microbes can also make other necessary nutrients available to plants.For the first generation of the seed coatings, he embedded these microbes in coatings made of silk — a material that he had previously shown can extend the shelf life of produce, meat, and other foods. In his lab at MIT, Marelli has shown that the seed coatings can help germinating plants survive drought, ultraviolet light exposure, and high salinity.Now, working with researchers at the Mohammed VI Polytechnic University in Morocco, he is adapting the approach to crops native to Morocco, a country that has experienced six consecutive years of drought due a drop in rainfall linked to climate change.For these studies, the researchers are using a biopolymer coating derived from food waste that can be easily obtained in Morocco, instead of silk.“We’re working with local communities to extract the biopolymers, to try to have a process that works at scale so that we make materials that work in that specific environment.” Marelli says. “We may come up with an idea here at MIT within a high-resource environment, but then to work there, we need to talk with the local communities, with local stakeholders, and use their own ingenuity and try to match our solution with something that could actually be applied in the local environment.”Microbes as fertilizersWhether they are experiencing drought or not, crops grow much better when synthetic fertilizers are applied. Although it’s essential to most farms, applying fertilizer is expensive and has environmental consequences. Most of the world’s fertilizer is produced using the Haber-Bosch process, which converts nitrogen and hydrogen to ammonia at high temperatures and pressures. This energy intensive process accounts for about 1.5 percent of the world’s greenhouse gas emissions, and the transportation required to deliver it to farms around the world adds even more emissions.Ariel Furst, the Paul M. Cook Career Development Assistant Professor of Chemical Engineering at MIT, is developing a microbial alternative to the Haber-Bosch process. Some farms have experimented with applying nitrogen-fixing bacteria directly to the roots of their crops, which has shown some success. However, the microbes are too delicate to be stored long-term or shipped anywhere, so they must be produced in a bioreactor on the farm.

      MIT chemical engineers devised a metal-organic coating that protects bacterial cells from damage without impeding their growth or function.

      To overcome those challenges, Furst has developed a way to coat the microbes with a protective shell that prevents them from being destroyed by heat or other stresses. The coating also protects microbes from damage caused by freeze-drying — a process that would make them easier to transport.The coatings can vary in composition, but they all consist of two components. One is a metal such as iron, manganese, or zinc, and the other is a polyphenol — a type of plant-derived organic compound that includes tannins and other antioxidants. These two components self-assemble into a protective shell that encapsulates bacteria.

      Play video

      Mighty Microbes: The Power of Protective PolymersVideo: Chemistry Shorts

      “These microbes would be delivered with the seeds, so it would remove the need for fertilizing mid-growing. It also reduces the cost and provides more autonomy to the farmers and decreases carbon emissions associated with agriculture,” Furst says. “We think it’ll be a way to make agriculture completely regenerative, so to bring back soil health while also boosting crop yields and the nutrient density of the crops.”Furst has founded a company called Seia Bio, which is working on commercializing the coated microbes and has begun testing them on farms in Brazil. In her lab, Furst is also working on adapting the approach to coat microbes that can capture carbon dioxide from the atmosphere and turn it into limestone, which helps to raise the soil pH.“It can help change the pH of soil to stabilize it, while also being a way to effectively perform direct air capture of CO2,” she says. “Right now, farmers may truck in limestone to change the pH of soil, and so you’re creating a lot of emissions to bring something in that microbes can do on their own.”Distress sensors for plantsSeveral years ago, Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT, began to explore the idea of using plants themselves as sensors that could reveal when they’re in distress. When plants experience drought, attack by pests, or other kinds of stress, they produce hormones and other signaling molecules to defend themselves.Strano, whose lab specializes in developing tiny sensors for a variety of molecules, wondered if such sensors could be deployed inside plants to pick up those distress signals. To create their sensors, Strano’s lab takes advantage of the special properties of single-walled carbon nanotubes, which emit fluorescent light. By wrapping the tubes with different types of polymers, the sensors can be tuned to detect specific targets, giving off a fluorescent signal when the target is present.For use in plants, Strano and his colleagues created sensors that could detect signaling molecules such as salicylic acid and hydrogen peroxide. They then showed that these sensors could be inserted into the underside of plant leaves, without harming the plants. Once embedded in the mesophyll of the leaves, the sensors can pick up a variety of signals, which can be read with an infrared camera.

      Sensors that detect plant signaling molecules can reveal when crops are experiencing too much light or heat, or attack from insects or microbes.

      These sensors can reveal, in real-time, whether a plant is experiencing a variety of stresses. Until now, there hasn’t been a way to get that information fast enough for farmers to act on it.“What we’re trying to do is make tools that get information into the hands of farmers very quickly, fast enough for them to make adaptive decisions that can increase yield,” Strano says. “We’re in the middle of a revolution of really understanding the way in which plants internally communicate and communicate with other plants.”This kind of sensing could be deployed in fields, where it could help farmers respond more quickly to drought and other stresses, or in greenhouses, vertical farms, and other types of indoor farms that use technology to grow crops in a controlled environment.Much of Strano’s work in this area has been conducted with the support of the U.S. Department of Agriculture (USDA) and as part of the Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) program at the Singapore-MIT Alliance for Research and Technology (SMART), and sensors have been deployed in tests in crops at a controlled environment farm in Singapore called Growy.“The same basic kinds of tools can help detect problems in open field agriculture or in controlled environment agriculture,” Strano says. “They both suffer from the same problem, which is that the farmers get information too late to prevent yield loss.”Reducing pesticide usePesticides represent another huge financial expense for farmers: Worldwide, farmers spend about $60 billion per year on pesticides. Much of this pesticide ends up accumulating in water and soil, where it can harm many species, including humans. But, without using pesticides, farmers may lose more than half of their crops.Kripa Varanasi, an MIT professor of mechanical engineering, is working on tools that can help farmers measure how much pesticide is reaching their plants, as well as technologies that can help pesticides adhere to plants more efficiently, reducing the amount that runs off into soil and water.Varanasi, whose research focuses on interactions between liquid droplets and surfaces, began to think about applying his work to agriculture more than a decade ago, after attending a conference at the USDA. There, he was inspired to begin developing ways to improve the efficiency of pesticide application by optimizing the interactions that occur at leaf surfaces.“Billions of drops of pesticide are being sprayed on every acre of crop, and only a small fraction is ultimately reaching and staying on target. This seemed to me like a problem that we could help to solve,” he says.Varanasi and his students began exploring strategies to make drops of pesticide stick to leaves better, instead of bouncing off. They found that if they added polymers with positive and negative charges, the oppositely charged droplets would form a hydrophilic (water-attracting) coating on the leaf surface, which helps the next droplets applied to stick to the leaf.

      AgZen has developed a system for farming that can monitor exactly how much of the sprayed chemicals adheres to plants, in real time, as the sprayer drives through a field.

      Later, they developed an easier-to-use technology in which a surfactant is added to the pesticide before spraying. When this mixture is sprayed through a special nozzle, it forms tiny droplets that are “cloaked” in surfactant. The surfactant helps the droplets to stick to the leaves within a few milliseconds, without bouncing off.In 2020, Varanasi and Vishnu Jayaprakash SM ’19, PhD ’22 founded a company called AgZen to commercialize their technologies and get them into the hands of farmers. They incorporated their ideas for improving pesticide adhesion into a product called EnhanceCoverage.During the testing for this product, they realized that there weren’t any good ways to measure how many of the droplets were staying on the plant. That led them to develop a product known as RealCoverage, which is based on machine vision. It can be attached to any pesticide sprayer and offer real-time feedback on what percentage of the pesticide droplets are sticking to and staying on every leaf.RealCoverage was used on 65,000 acres of farmland across the United States in 2024, from soybeans in Iowa to cotton in Georgia. Farmers who used the product were able to reduce their pesticide use by 30 to 50 percent, by using the data to optimize delivery and, in some cases, even change what chemicals were sprayed.He hopes that the EnhanceCoverage product, which is expected to become available in 2025, will help farmers further reduce their pesticide use.“Our mission here is to help farmers with savings while helping them achieve better yields. We have found a way to do all this while also reducing waste and the amount of chemicals that we put into our atmosphere and into our soils and into our water,” Varanasi says. “This is the MIT approach: to figure out what are the real issues and how to come up with solutions. Now we have a tool and I hope that it’s deployed everywhere and everyone gets the benefit from it.” More

    • 75 Shares119 Views

      in Environment

      Study: Marshes provide cost-effective coastal protection

      by

      Images of coastal houses being carried off into the sea due to eroding coastlines and powerful storm surges are becoming more commonplace as climate change brings a rising sea level coupled with more powerful storms. In the U.S. alone, coastal storms caused $165 billion in losses in 2022.Now, a study from MIT shows that protecting and enhancing salt marshes in front of protective seawalls can significantly help protect some coastlines, at a cost that makes this approach reasonable to implement.The new findings are being reported in the journal Communications Earth and Environment, in a paper by MIT graduate student Ernie I. H. Lee and professor of civil and environmental engineering Heidi Nepf. This study, Nepf says, shows that restoring coastal marshes “is not just something that would be nice to do, but it’s actually economically justifiable.” The researchers found that, among other things, the wave-attenuating effects of salt marsh mean that the seawall behind it can be built significantly lower, reducing construction cost while still providing as much protection from storms.“One of the other exciting things that the study really brings to light,” Nepf says, “is that you don’t need a huge marsh to get a good effect. It could be a relatively short marsh, just tens of meters wide, that can give you benefit.” That makes her hopeful, Nepf says, that this information might be applied in places where planners may have thought saving a smaller marsh was not worth the expense. “We show that it can make enough of a difference to be financially viable,” she says.While other studies have previously shown the benefits of natural marshes in attenuating damaging storms, Lee says that such studies “mainly focus on landscapes that have a wide marsh on the order of hundreds of meters. But we want to show that it also applies in urban settings where not as much marsh land is available, especially since in these places existing gray infrastructure (seawalls) tends to already be in place.”The study was based on computer modeling of waves propagating over different shore profiles, using the morphology of various salt marsh plants — the height and stiffness of the plants, and their spatial density — rather than an empirical drag coefficient. “It’s a physically based model of plant-wave interaction, which allowed us to look at the influence of plant species and changes in morphology across seasons,” without having to go out and calibrate the vegetation drag coefficient with field measurements for each different condition, Nepf says.The researchers based their benefit-cost analysis on a simple metric: To protect a certain length of shoreline, how much could the height of a given seawall be reduced if it were accompanied by a given amount of marsh? Other ways of assessing the value, such as including the value of real estate that might be damaged by a given amount of flooding, “vary a lot depending on how you value the assets if a flood happens,” Lee says. “We use a more concrete value to quantify the benefits of salt marshes, which is the equivalent height of seawall you would need to deliver the same protection value.”They used models of a variety of plants, reflecting differences in height and the stiffness across different seasons. They found a twofold variation in the various plants’ effectiveness in attenuating waves, but all provided a useful benefit.To demonstrate the details in a real-world example and help to validate the simulations, Nepf and Lee studied local salt marshes in Salem, Massachusetts, where projects are already underway to try to restore marshes that had been degraded. Including the specific example provided a template for others, Nepf says. In Salem, their model showed that a healthy salt marsh could offset the need for an additional seawall height of 1.7 meters (about 5.5 feet), based on satisfying a rate of wave overtopping that was set for the safety of pedestrians.However, the real-world data needed to model a marsh, including maps of salt marsh species, plant height, and shoots per bed area, are “very labor-intensive” to put together, Nepf says. Lee is now developing a method to use drone imaging and machine learning to facilitate this mapmaking. Nepf says this will enable researchers or planners to evaluate a given area of marshland and say, “How much is this marsh worth in terms of its ability to reduce flooding?”The White House Office of Information and Regulatory Affairs recently released guidance for assessing the value of ecosystem services in planning of federal projects, Nepf explains.  “But in many scenarios, it lacks specific methods for quantifying value, and this study is meeting that need,” she says.The Federal Emergency Management Agency also has a benefit-cost analysis (BCA) toolkit, Lee notes. “They have guidelines on how to quantify each of the environmental services, and one of the novelties of this paper is quantifying the cost and the protection value of marshes. This is one of the applications that policymakers can consider on how to quantify the environmental service values of marshes,” he says.The software that environmental engineers can apply to specific sites has been made available online for free on GitHub. “It’s a one-dimensional model accessible by a standard consulting firm,” Nepf says.“This paper presents a practical tool for translating the wave attenuation capabilities of marshes into economic values, which could assist decision-makers in the adaptation of marshes for nature-based coastal defense,” says Xioaxia Zhang, a professor at Shenzen University in China who was not involved in this work. “The results indicate that salt marshes are not only environmentally beneficial but also cost-effective.”The study “is a very important and crucial step to quantifying the protective value of marshes,” adds Bas Borsje, an associate professor of nature-based flood protection at the University of Twente in the Netherlands, who was not associated with this work. “The most important step missing at the moment is how to translate our findings to the decision makers. This is the first time I’m aware of that decision-makers are quantitatively informed on the protection value of salt marshes.”Lee received support for this work from the Schoettler Scholarship Fund, administered by the MIT Department of Civil and Environmental Engineering. More

    • 125 Shares99 Views

      in Environment

      How climate change will impact outdoor activities in the US

      by

      It can be hard to connect a certain amount of average global warming with one’s everyday experience, so researchers at MIT have devised a different approach to quantifying the direct impact of climate change. Instead of focusing on global averages, they came up with the concept of “outdoor days”: the number days per year in a given location when the temperature is not too hot or cold to enjoy normal outdoor activities, such as going for a walk, playing sports, working in the garden, or dining outdoors.In a study published earlier this year, the researchers applied this method to compare the impact of global climate change on different countries around the world, showing that much of the global south would suffer major losses in the number of outdoor days, while some northern countries could see a slight increase. Now, they have applied the same approach to comparing the outcomes for different parts of the United States, dividing the country into nine climatic regions, and finding similar results: Some states, especially Florida and other parts of the Southeast, should see a significant drop in outdoor days, while some, especially in the Northwest, should see a slight increase.The researchers also looked at correlations between economic activity, such as tourism trends, and changing climate conditions, and examined how numbers of outdoor days could result in significant social and economic impacts. Florida’s economy, for example, is highly dependent on tourism and on people moving there for its pleasant climate; a major drop in days when it is comfortable to spend time outdoors could make the state less of a draw.The new findings were published this month in the journal Geophysical Research Letters, in a paper by researchers Yeon-Woo Choi and Muhammad Khalifa and professor of civil and environmental engineering Elfatih Eltahir.“This is something very new in our attempt to understand impacts of climate change impact, in addition to the changing extremes,” Choi says. It allows people to see how these global changes may impact them on a very personal level, as opposed to focusing on global temperature changes or on extreme events such as powerful hurricanes or increased wildfires. “To the best of my knowledge, nobody else takes this same approach” in quantifying the local impacts of climate change, he says. “I hope that many others will parallel our approach to better understand how climate may affect our daily lives.”The study looked at two different climate scenarios — one where maximum efforts are made to curb global emissions of greenhouse gases and one “worst case” scenario where little is done and global warming continues to accelerate. They used these two scenarios with every available global climate model, 32 in all, and the results were broadly consistent across all 32 models.The reality may lie somewhere in between the two extremes that were modeled, Eltahir suggests. “I don’t think we’re going to act as aggressively” as the low-emissions scenarios suggest, he says, “and we may not be as careless” as the high-emissions scenario. “Maybe the reality will emerge in the middle, toward the end of the century,” he says.The team looked at the difference in temperatures and other conditions over various ranges of decades. The data already showed some slight differences in outdoor days from the 1961-1990 period compared to 1991-2020. The researchers then compared these most recent 30 years with the last 30 years of this century, as projected by the models, and found much greater differences ahead for some regions. The strongest effects in the modeling were seen in the Southeastern states. “It seems like climate change is going to have a significant impact on the Southeast in terms of reducing the number of outdoor days,” Eltahir says, “with implications for the quality of life of the population, and also for the attractiveness of tourism and for people who want to retire there.”He adds that “surprisingly, one of the regions that would benefit a little bit is the Northwest.” But the gain there is modest: an increase of about 14 percent in outdoor days projected for the last three decades of this century, compared to the period from 1976 to 2005. The Southwestern U.S., by comparison, faces an average loss of 23 percent of their outdoor days.The study also digs into the relationship between climate and economic activity by looking at tourism trends from U.S. National Park Service visitation data, and how that aligned with differences in climate conditions. “Accounting for seasonal variations, we find a clear connection between the number of outdoor days and the number of tourist visits in the United States,” Choi says.For much of the country, there will be little overall change in the total number of annual outdoor days, the study found, but the seasonal pattern of those days could change significantly. While most parts of the country now see the most outdoor days in summertime, that will shift as summers get hotter, and spring and fall will become the preferred seasons for outdoor activity.In a way, Eltahir says, “what we are talking about that will happen in the future [for most of the country] is already happening in Florida.” There, he says, “the really enjoyable time of year is in the spring and fall, and summer is not the best time of year.”People’s level of comfort with temperatures varies somewhat among individuals and among regions, so the researchers designed a tool, now freely available online, that allows people to set their own definitions of the lowest and highest temperatures they consider suitable for outdoor activities, and then see what the climate models predict would be the change in the number of outdoor days for their location, using their own standards of comfort. For their study, they used a widely accepted range of 10 degrees Celsius (50 degrees Fahrenheit) to 25 C (77 F), which is the “thermoneutral zone” in which the human body does not require either metabolic heat generation or evaporative cooling to maintain its core temperature — in other words, in that range there is generally no need to either shiver or sweat.The model mainly focuses on temperature but also allows people to include humidity or precipitation in their definition of what constitutes a comfortable outdoor day. The model could be extended to incorporate other variables such as air quality, but the researchers say temperature tends to be the major determinant of comfort for most people.Using their software tool, “If you disagree with how we define an outdoor day, you could define one for yourself, and then you’ll see what the impacts of that are on your number of outdoor days and their seasonality,” Eltahir says.This work was inspired by the realization, he says, that “people’s understanding of climate change is based on the assumption that climate change is something that’s going to happen sometime in the future and going to happen to someone else. It’s not going to impact them directly. And I think that contributes to the fact that we are not doing enough.”Instead, the concept of outdoor days “brings the concept of climate change home, brings it to personal everyday activities,” he says. “I hope that people will find that useful to bridge that gap, and provide a better understanding and appreciation of the problem. And hopefully that would help lead to sound policies that are based on science, regarding climate change.”The research was based on work supported by the Community Jameel for Jameel Observatory CREWSnet and Abdul Latif Jameel Water and Food Systems Lab at MIT. More