Environment

GPS isn’t waterproof. The navigation system depends on radio waves, which break down rapidly in liquids, including seawater. To track undersea objects like drones or whales, researchers rely on acoustic signaling. But devices that generate and send sound usually require batteries — bulky, short-lived batteries that need regular changing. Could we do without them?
MIT researchers think so. They’ve built a battery-free pinpointing system dubbed Underwater Backscatter Localization (UBL). Rather than emitting its own acoustic signals, UBL reflects modulated signals from its environment. That provides researchers with positioning information, at net-zero energy. Though the technology is still developing, UBL could someday become a key tool for marine conservationists, climate scientists, and the U.S. Navy.
These advances are described in a paper being presented this week at the Association for Computing Machinery’s Hot Topics in Networks workshop, by members of the Media Lab’s Signal Kinetics group. Research Scientist Reza Ghaffarivardavagh led the paper, along with co-authors Sayed Saad Afzal, Osvy Rodriguez, and Fadel Adib, who leads the group and is the Doherty Chair of Ocean Utilization as well as an associate professor in the MIT Media Lab and the MIT Department of Electrical Engineering and Computer Science.
“Power-hungry”
It’s nearly impossible to escape GPS’ grasp on modern life. The technology, which relies on satellite-transmitted radio signals, is used in shipping, navigation, targeted advertising, and more. Since its introduction in the 1970s and ’80s, GPS has changed the world. But it hasn’t changed the ocean. If you had to hide from GPS, your best bet would be underwater.
Because radio waves quickly deteriorate as they move through water, subsea communications often depend on acoustic signals instead. Sound waves travel faster and further underwater than through air, making them an efficient way to send data. But there’s a drawback.
“Sound is power-hungry,” says Adib. For tracking devices that produce acoustic signals, “their batteries can drain very quickly.” That makes it hard to precisely track objects or animals for a long time-span — changing a battery is no simple task when it’s attached to a migrating whale. So, the team sought a battery-free way to use sound.
Good vibrations
Adib’s group turned to a unique resource they’d previously used for low-power acoustic signaling: piezoelectric materials. These materials generate their own electric charge in response to mechanical stress, like getting pinged by vibrating soundwaves. Piezoelectric sensors can then use that charge to selectively reflect some soundwaves back into their environment. A receiver translates that sequence of reflections, called backscatter, into a pattern of 1s (for soundwaves reflected) and 0s (for soundwaves not reflected). The resulting binary code can carry information about ocean temperature or salinity.
In principle, the same technology could provide location information. An observation unit could emit a soundwave, then clock how long it takes that soundwave to reflect off the piezoelectric sensor and return to the observation unit. The elapsed time could be used to calculate the distance between the observer and the piezoelectric sensor. But in practice, timing such backscatter is complicated, because the ocean can be an echo chamber.
The sound waves don’t just travel directly between the observation unit and sensor. They also careen between the surface and seabed, returning to the unit at different times. “You start running into all of these reflections,” says Adib. “That makes it complicated to compute the location.” Accounting for reflections is an even greater challenge in shallow water — the short distance between seabed and surface means the confounding rebound signals are stronger.
The researchers overcame the reflection issue with “frequency hopping.” Rather than sending acoustic signals at a single frequency, the observation unit sends a sequence of signals across a range of frequencies. Each frequency has a different wavelength, so the reflected sound waves return to the observation unit at different phases. By combining information about timing and phase, the observer can pinpoint the distance to the tracking device. Frequency hopping was successful in the researchers’ deep-water simulations, but they needed an additional safeguard to cut through the reverberating noise of shallow water.
Where echoes run rampant between the surface and seabed, the researchers had to slow the flow of information. They reduced the bitrate, essentially waiting longer between each signal sent out by the observation unit. That allowed the echoes of each bit to die down before potentially interfering with the next bit. Whereas a bitrate of 2,000 bits/second sufficed in simulations of deep water, the researchers had to dial it down to 100 bits/second in shallow water to obtain a clear signal reflection from the tracker. But a slow bitrate didn’t solve everything.
To track moving objects, the researchers actually had to boost the bitrate. One thousand bits/second was too slow to pinpoint a simulated object moving through deep water at 30 centimeters/second. “By the time you get enough information to localize the object, it has already moved from its position,” explains Afzal. At a speedy 10,000 bits/second, they were able to track the object through deep water.
Efficient exploration
Adib’s team is working to improve the UBL technology, in part by solving challenges like the conflict between low bitrate required in shallow water and the high bitrate needed to track movement. They’re working out the kinks through tests in the Charles River. “We did most of the experiments last winter,” says Rodriguez. That included some days with ice on the river. “It was not very pleasant.”
Conditions aside, the tests provided a proof-of-concept in a challenging shallow-water environment. UBL estimated the distance between a transmitter and backscatter node at various distances up to nearly half a meter. The team is working to increase UBL’s range in the field, and they hope to test the system with their collaborators at the Wood Hole Oceanographic Institution on Cape Cod.
They hope UBL can help fuel a boom in ocean exploration. Ghaffarivardavagh notes that scientists have better maps of the moon’s surface than of the ocean floor. “Why can’t we send out unmanned underwater vehicles on a mission to explore the ocean? The answer is: We will lose them,” he says.
UBL could one day help autonomous vehicles stay found underwater, without spending precious battery power. The technology could also help subsea robots work more precisely, and provide information about climate change impacts in the ocean. “There are so many applications,” says Adib. “We’re hoping to understand the ocean at scale. It’s a long-term vision, but that’s what we’re working toward and what we’re excited about.”
This work was supported, in part, by the Office of Naval Research. More

Nacre, the iridescent material that lines mollusk shells such as mother-of-pearl and abalone, has long been a prized find of beachcombers and shell collectors, due to the natural beauty and variety of color that can be found therein. But scientists and engineers have also long marveled at and studied nacre; it’s a tough and strong material, composed of alternating layers of aragonite platelets and organic protein-based film. The natural world contains many materials that have evolved over time to optimize strength, durability, and performance. As researchers and engineers look to develop improved and more sustainable building materials, they are increasingly looking to nature for inspiration.
The physical makeup of nacre allows it to withstand considerable amounts of pressure and damage along the platelets without causing major damage throughout the whole shell. It has been supposed by some that more is at play of the individual platelets that allows them such extraordinary strength and durability, but researchers have lacked the tools and processes to dig deeper into the relationship between the crystal orientation and the mechanical properties — until now.
Over the past two decades, the shells have typically been tested for their strength using techniques such as macroscopic bending test, micro-/nano-indentation, and atomic force microscope. Now, MIT assistant professor of civil and environmental engineering Admir Masic, graduate student Hyun-Chae “Chad” Loh, and five others have combined scanning electron microscopy and micro-indentation with Raman spectroscopy and developed a powerful chemo-mechanical characterization method that allows three-dimensional stress and strain mapping through a technique known as piezo-Raman.
“We developed a methodology to extract important chemo-mechanical information from a biological system that is very well known and studied,” explains Masic, whose findings were recently published in Communications Materials. “Correlating micro-indentation and piezo-Raman results allowed us to evaluate and quantify the amount of stress dissipated through the hierarchical structure.”
The new approach to quantifying the mechanical performance of the material is enough to be big news on its own, but during the process, Masic and fellow researchers — whom he credits with much of the work in this collaborative effort — were surprised by the results.
“We first applied these tools to study the strain-hardening mechanism in a few microns scale. However, we noticed that the dissipation of energy was not confined to the brick-and-mortar structure, but was affecting a much larger area than we expected. We expanded our scope of study to a larger scale and found this new toughening mechanism that is related to a mesostructure on a scale of 20 microns,” says Loh. What the researchers found is that stacks of co-oriented aragonite platelets constitute another hierarchical level of structure, which toughens the material as it is stressed.
Polarized Raman, another technique used in this study, helped the team observe what’s known as the crystallographic orientation of the aragonite bricks. Through the investigation of the orientation patterns, researchers were able to elucidate the characteristic length scale of the aragonite stacks and relate it to the crack propagation patterns. The cracks propagated between the aragonite stacks, evincing their mechanical contribution to nacre’s toughness.
“This gave us an opening for potentially explaining what is causing this toughening at the larger scales. Systematic arrangements of crystals can be found within other biomineral materials, such as our teeth, and the micro-texture of the materials directly impacts their function.” says Masic.
Mimicking natural materials like nacre has been a popular strategy for designing new materials. The small scale of their structures, however, poses a challenge for replicating and manufacturing the natural morphologies. “With our discovery, we propose a new biomimicry strategy of simulating nacre’s structure on a 10-micron or bigger scale, instead of the nano level.” says Masic.
It’s exciting news for researchers who are exploring new possibilities for synthetic materials inspired by natural design.
This research was funded, in part, by Kwanjeong Educational Foundation. More

The Kingdom of Saudi Arabia (KSA) is at a crossroads. Recent long-term studies of the area indicate that rising temperatures and evaporation rates will likely further deplete scarce water resources critical to meeting the nation’s agricultural, industrial, and domestic needs; more extreme flooding events could endanger lives, economic vitality, and infrastructure; and a combination of increasing heat and humidity levels may ultimately render the kingdom uninhabitable. Facing a foreboding future, how might the nation adapt to changing climatic conditions and become more resilient to climate extremes?
Due to the KSA’s distinctive natural and artificial features, from coastal landscapes to river beds to agricultural areas, decision-makers seeking to design actionable plans for regional and local adaptation and resilience will require projections of the KSA’s mean climate and extreme events at a higher spatial resolution than what previous studies have produced.     
To that end, a team of researchers from the MIT Joint Program on the Science and Policy of Global Change and the King Abdulaziz City for Science and Technology’s Center for Complex Engineering Systems used a high-resolution, regional climate modeling approach to generate mid-21st century (2041–2050) projections under a high-emissions, high-climate-impact scenario. The climate projections carry an unprecedented four-kilometer horizontal resolution and cover the entire KSA, and focus exclusively on the months of August and November. During these months, which represent, respectively, the KSA’s dry-hot and wet seasons, extreme events have been observed more frequently.
Applying this modeling approach, the team projected increasing temperatures by mid-century across the KSA, including five strategic locations — the capital city of Riyadh, religious tourism destinations Makkah and Madinah, the designated future tourist site of Tabuk, and the port city of Jeddah — in both August and November, and a rising August heat index (high heat and humidity) that particularly threatens regional habitability in Jeddah due to an increasing frequency of extreme heat index days.
The researchers also found an increase in the intensity and frequency of precipitation events in August by mid-century, particularly along the nation’s mountainous western coast, suggesting a potential for water harvesting — that could replenish local aquifers and supplement water supplies elsewhere — as a regional climate adaptation strategy to avert future water scarcity. The projections also showed a significant decline in precipitation rates in a sizeable stretch of desert extending from the southern portion of the country known as the Empty Quarter. 
The study appears in the journal Atmosphere.
“The intent of our research was to highlight the potential use of our modeling approach not only to generate high-resolution climate projections that capture the effects of unique local spatial features, but also to enable local solutions for climate adaption and resilience in the region,” says Muge Komurcu, the study’s lead author and a research scientist at the MIT Joint Program.  
The study was funded by MIT and the Center for Complex Engineering Systems at the King Abdulaziz City for Science and Technology. More

Under its Plan for Action on Climate Change, MIT has a goal of reducing its greenhouse gas emissions by at least 32 percent below its 2014 emission levels, by 2030. Those reductions are now at 24 percent, and the Institute is track to meet or exceed the goal, said Joe Higgins, vice president for campus services and stewardship, thanks to Institute-wide efforts that benefit from connecting research and operations.
In the fifth of six symposia in the Climate Action series, held Oct. 20, an online panel of MIT experts including Higgins discussed the role of research universities in tackling climate change. Research universities like MIT provide critical technology and policy innovations, the speakers said, but can also act as role models for other institutions.
“Higher education has a responsibility, an opportunity to set their sights on being an exemplar organization and community in how to face, respond to, and address the climate change issue,” said Professor Paula Hammond, head of the Department of Chemical Engineering and a co-chair of the symposium.
The 170 acres of the MIT campus and its affiliate programs are a kind of living laboratory and testbed for climate solutions, “to demonstrate the technology and the choices that we as people make to move the campus forward,” said Krystyn Van Vliet, associate provost and professor of materials science and engineering and of biological engineering.
In one effort to connect research and operations, Higgins and his colleagues asked participants at the 2018 MIT Energy Hack to find ways of using machine learning to reduce emissions in large buildings. The MIT Sustainability DataPool, a portal of campus sustainability data open to the MIT community, is another way the Institute encourages its researchers “to use the campus as a testbed to generate game-changing solutions” to climate challenges, said Julie Newman, director of sustainability and lecturer in the Department of Urban Studies and Planning.
Having this model in place was a tremendous help when the Covid-19 pandemic created a new influx of personal protective equipment (PPE) and single-use plastic items to manage within the campus’ consumption and waste sustainability plan, said Newman, also a symposium co-chair. “When all of a sudden the challenge of Covid comes and we notice that we’re going to have to grapple with supply chain and use and disposal of PPE, it didn’t take but a couple of weeks to reach out and pull together a research team, an operations team, a finance team, and say let’s study this in MIT style.”
Research universities must be a source of innovations to address global climate change, said Associate Provost Richard Lester, “because our existing government-led innovation system is falling short, even relative to the inadequate benchmarks set by governments themselves.”
Among the efforts to encourage these innovations is MIT Climate Grand Challenges, a program launched in July 2020 that encourages all MIT researchers to develop and implement climate mitigation and adaptation solutions. The program already has received more than 100 letters of interest from more 300 faculty and senior researchers, Lester said.
Technological breakthroughs are still needed urgently to stop the buildup of greenhouse gases in the atmosphere, despite the talk among some experts that the technological solutions are already available, said Maria Zuber, MIT vice president for research and the E.A. Griswold Professor of Geophysics.
“I wish these individuals who think we have the technology were right. But they’re not. We do not currently have the technology we need to rapidly and adequately make the needed energy transition,” Zuber said. “This is why our work at MIT matters so much.”
Climate solutions must include more than just advanced science and technology capabilities, said Melissa Nobles, the Kenan Sahin Dean of the School of Humanities, Arts, and Social Sciences, and professor of political science. At MIT, she notes, classes on the ethics of climate change, the J-PAL King Climate Action Initiative, and Charlotte Brathwaite’s “Bee Boy” theater project are some examples of how the social sciences and arts can be brought to bear on climate issues.
“As I see it, the more that research institutions can invent practical ways for these various forms of knowledge to intersect, blend, and become mutually informing, the more quickly we can generate effective climate solutions,” Nobles said.
At the same time, universities should remember that climate change policy is only one of several issues, including global health, poverty, and racism, “which deserve and command our attention,” said Institute Professor Emeritus John Deutch. He also sounded a note of caution about how universities should engage in policy discussions. “They cannot speak out with one voice, or should do so very rarely,” he said, because members of the university community often hold diverse opinions and points of view.
The final symposium in the series, “What is the World Waiting For? Policies to Fight Climate Change” will take place online Nov. 16. More

We have all faced new and greater challenges this year. The Covid-19 pandemic has spared no country, family, or individual, but it has not impacted us all equally. It is those most disadvantaged and most underserved who have been hit the hardest. The team at MIT Solve felt an immediate responsibility to use its work and privilege to take action in this historic moment, to mobilize its community to address the problems aggravated by the pandemic. The Solve Global Challenges that had launched in February 2020 suddenly became all the more pressing. And, for the first time in its history, Solve launched a rapid-response Challenge on Health Security and Pandemics on March 5. 
Then, something amazing happened: Solve received over 2,600 solutions from 135 countries — an 86 percent increase in applications year-over-year. It is no coincidence that, in this year of great upheaval and disruption, problem-solvers around the world leaped to the call. It tells an inspiring and hopeful story about our ability as human beings to see an opportunity, and fix challenges.
Solve Challenge Finals was a celebration of that spirit. Of all those submissions, the Solve team showcased the solutions that its judges selected as the most promising, inventive, and impactful from all around the world. While it’s hard to beat the energy that comes from meeting in person, one silver lining of coming together virtually was that all of the finalists were able to attend without the extra stress of visas, plane tickets, and jet lag. 
Some 90 finalists from across the world spoke on solutions like Biometrics for Vaccine Delivery, which uses contactless biometrics to ensure vaccines reach every intended beneficiary at the frontline in Africa and Asia; ShockTalk, a telebehavioral app for Indigenous users, made more crucial by the rise of mental health struggles in the pandemic; and The Last Mile, which provides in-prison tech education and post-incarceration mentorship to combat the problem of recidivism in the U.S. Ultimately, Solve’s expert judges selected 35 new Solver teams — including Yiya AirScience, co-founded by Erin Fitzgerald ’09, which provides rural African girls access to interactive learning experiences through simple keypad phones — and eight new Indigenous Communities Fellows.
Sal Khan ’98, MNG ’98, who has singularly shaped remote learning, joined the proceedings from the very closet where he founded Khan Academy. Speaking with NPR’s Anya Kamanetz, he shared insights from his own entrepreneurial journey and advised aspiring innovators that one secret to success is “to always have a side project.” After all, Khan Academy first started out as Khan’s post-work passion project.
One of the Indigenous Communities finalists stressed the importance of community in powering innovation: “It takes a community, it takes a community, it takes a community! It is necessary for our people and for our earth to be able to connect together. It starts in this kind of competition — to be able to look each other in the eye and say let’s go. And how far can we go? Endless possibilities!” This was the energizing message of Tiana Henderson, founder of Hale Unfolded.
Two speakers spoke to the cultural moment we are in today. Phillip Atiba Goff, co-founder and CEO of the Center for Policing Equity, emphasized that in order to truly solve a problem, we must first correctly diagnose it. He shared this crucial message when discussing the Breonna Taylor tragedy, and how racism in policing is just one symptom of broader racism in society. Goff called on finalists to dig deeply into the issues they are trying to solve. He remarked: “As technologists and problem-solvers, if we fail to diagnose the problem correctly, we will build a suite of tech toys instead of tools. If we get the diagnosis wrong, the set of solutions we build will be entirely unable to speak to the scale of the problem. In the context of policing, if we don’t recognize that it is part of a broader issue and not the issue itself, we are going to be creating tools that are too small to make a difference.”
Artist and gender liberation activist Madame Gandhi delivered two powerful musical performances and a message of defiance: “I don’t want our identity to be defined by how oppressed we are.” She called for more voices like hers in the music industry. With only 2 percent of music producers identifying as women, the narrative in too much of the music we consume is still perpetuating myths that hold us back. “I — like many of you — am here to design and provide the alternative.”  
Speakers including Harry Moseley, Global CIO of Zoom, also discussed the pivot to remote work and schooling resulting from this pandemic, and how to  find opportunities for greater inclusion as we reshape the status quo we’ve taken for granted for so long.
MIT Solve will work closely with its newly selected Solver teams to scale their work and impact across all of the 2020 Challenges. More

Renowned atmospheric chemist and MIT Institute Professor Emeritus Mario Molina, who discovered that chlorofluorocarbons (CFCs) had the potential to destroy the ozone layer in the Earth’s stratosphere, has died at the age of 77.
At MIT, Molina held joint appointments in the Department of Earth, Atmospheric and Planetary Sciences (EAPS) and the Department of Chemistry, from 1989 to 2004.
In the early 1970s, Molina demonstrated through computer modeling and laboratory work that compounds widely used in propellants and refrigerants could destroy ozone in the upper atmosphere, increasing the ultraviolet radiation reaching Earth. His theories were later confirmed by observation and helped support the ratification of the Montreal Protocol, the first global treaty to reduce CFC emissions.
In 1995, he shared the Nobel Prize in Chemistry with F. Sherwood Rowland of the University of California at Irvine, and Paul Crutzen, a scientist at the Max Planck Institute for Chemistry in Mainz, Germany, for discovering the depletion of the Earth’s thin, protective layer of ozone, which the Nobel committee referred to as the “Achilles heel of the universe.” Molina continued to advocate for environmental causes throughout his career.
“Mario Molina was the gentle giant of his age in environmental science, a wise mentor to his students, and respectful of others no matter their rank or status,” says Ronald Prinn, the TEPCO Professor of Atmospheric Science in EAPS, who led the search committee that originally brought Molina to MIT. “We are privileged to have had him on the faculty at MIT for 15 years, during the middle of which he was awarded the Nobel Prize, and from the proceeds of which he established the Molina Fellowships at MIT. His work on mitigating depletion of the ozone layer and air pollution in megacities is legendary. Most recently he founded the Centro Mario Molina devoted to the transition from fossil energy to clean energy in Mexico and beyond. He will be sorely missed, but never forgotten.”
Early scientific inquiry
Born on March 19, 1943 in Mexico City, Molina was enthralled by science from a young age. He used toy microscopes and chemistry sets to create his own “lab” in the bathroom of his childhood home. His aunt, a chemist, supported these early scientific interests by helping him conduct experiments more advanced than amateur chemistry sets would allow.
He attended school in Mexico City; later, his parents sent him abroad to the Institute Rosenberg in Switzerland, hoping to support his scientific proclivity. Molina attended the Universidad Nacional Autónoma de México (UNAM), where he completed his bachelor’s degree in chemical engineering in 1965, followed by a postgraduate degree in polymerization kinetics from the Albert Ludwig University of Freiburg, West Germany, in 1967. The University of California at Berkeley awarded him a PhD in physical chemistry in 1972.
Environmental reactions
In 1973, Molina began his CFC research as a postdoc at the University of California at Irvine, in the lab of F. Sherwood Rowland, who initially presented Molina with a list of research options. Molina latched quickly to one in particular: tracking the environmental fate of CFCs, the industrial chemicals that had been building up in the atmosphere and at the time were thought to have no adverse effects on the environment.
After simulating the chemicals’ reaction behavior and kinetics, Molina found that there was not much that could break down CFCs in the lower atmosphere. He suspected, however, that CFCs could be detrimental at higher altitudes, and hypothesized that high-energy photons from the sun available within the stratosphere could break the chemicals apart, generating free chlorine ions that would then react destructively with ozone molecules. Rowland and Molina published their work in the journal Nature in 1974.
That year, Molina and Rowland publicly called for a ban on CFCs at the American Chemical Society meeting. Molina also began teaching atmospheric science, holding positions at UC Irvine from 1975 to 1982 and conducting research at Caltech’s Jet Propulsion Laboratory from 1982 to 1989. Initially disputed by industry, Molina’s work began to gain traction, first when it was reviewed by the National Academy of Sciences in 1976, and then even more so when a hole in the Antarctic ozone later was first reported in 1985.
In 1987, his work, in part, inspired atmospheric chemist Susan Solomon to lead a scientific expedition to Antarctica, the results of which proved that the ozone hole was indeed caused by CFCs. The Montreal Protocol to phase out CFCs went into effect in 1989, the same year that Molina joined the faculty at MIT.
Molina was awarded the 1995 Nobel Prize in Chemistry with his colleagues for their work on CFCs and ozone depletion — the first time the Swedish Academy recognized environmental degradation from human-made substances. Molina donated a substantial portion of his share of the prize money to MIT in 1996 to create a fellowship program for scientists from developing countries to pursue environmental research.
“It’s clear to me that one of the important needs for global environment issues is the participation of scientists from all over the world,” Molina said in announcing the gift. “We have some very big challenges ahead if we are to preserve the environment, and it’s obvious that there are too few scientists from developing countries involved in the effort.”
Molina continued his work in atmospheric chemistry while at MIT, studying the atmosphere-biosphere interface, hoping to better understand global climate change.
“The signature feature of Mario Molina was that he was not only a great scientist and scholar, he was also a true gentlemen — always ready with a smile and focused on the person he was speaking with, whether it was an undergraduate student or a fellow Nobel laureate,” says Solomon, who is the Lee and Geraldine Martin Professor of Environmental Studies in EAPS and holds a secondary appointment in the Department of Chemistry.
“His humanity and his science”
In 1994 Molina was named by U.S. President Bill Clinton to serve on the 18-member President’s Committee of Advisors on Science and Technology (PCAST). Later, he also served on President Barack Obama’s Council of Advisors on Science and Technology in 2011, and received the Presidential Medal of Freedom from President Obama in 2016.
MIT appointed him an Institute Professor for his abilities as a “natural educator” and excellence in research in 1997.
Molina often traveled to Mexico to work on environmental projects. While at MIT, he collaborated with policymakers and researchers to reduce Mexico City’s severe air pollution and improve air quality. In 2004, he founded the Mario Molina Center for Strategic Studies in Energy and the Environment in Mexico City, an organization dedicated to bridging “practical solutions between science and public policy on energy and environment matters to promote sustainable development and vigorous economic growth.” That same year, he left MIT to join the Scripps Institution of Oceanography and the Department of Chemistry and Biochemistry at University of California at San Diego. In 2017, he was inducted into the California Hall of Fame.
“Mario Molina is unique in his ability to span from fundamental science to local and global policy for stewarding our environment. He towers in his humanity as well as his science,” said MIT President Charles M. Vest on Molina’s departure.
Molina was awarded numerous honorary degrees from institutions including Harvard University, Duke University, and Yale University, as well as institutions in Mexico. He was elected to the National Academy of Sciences in 1993, the United States Institute of Medicine in 1996, and The National College of Mexico in 2003. He was a member of the Mexican Academy of Sciences and a fellow of the American Association for the Advancement of Science (AAAS), and served on numerous advisory councils, including the National Science Foundation’s Advisory Committee for Geosciences.
In addition to his Nobel Prize, Molina received the Tyler Prize for Environmental Achievement, the UNEP-Sasakawa Environment Prize, and the United Nations Champion of the Earth Award. He was bestowed the Knight Medal of the Legion of Honor by French President Francois Hollande in 2014. He was awarded the Esselen Award of the Northeast section of the American Chemical Society in 1987, the Newcomb-Cleveland Prize from AAAS in 1988, as well as the NASA Medal for Exceptional Scientific Advancement and the United Nations Environmental Programme Global 500 Award in 1989.
Additionally, the Pew Charitable Trusts Scholars Program in Conservation and the Environment honored him as a leading environmental scientist in 1990. Molina was given the Golden Plate Award of the American Academy of Achievement in 1996. He won the Willard Gibbs Award from the Chicago Section of the American Chemical Society and the American Chemical Society Prize for Creative Advances in Environment Technology and Science in 1998. He was granted the 9th Annual Heinz Award in the Environment. He also had an asteroid named after him: 9680 Molina.
Molina is survived by his wife, Guadalupe Álvarez; his son, Felipe Jose Molina; and three stepsons, Joshua, Allan, and Asher Ginsburg. He was previously married to atmospheric chemist Luisa Tan Molina, an EAPS research affiliate. More

Although we can’t see it in action, the Earth is constantly churning out new land. This takes place at subduction zones, where tectonic plates crush against each other and in the process plow up chains of volcanos that magma can rise through. Some of this magma does not spew out, but instead mixes and morphs just below the surface. It then crystallizes as new continental crust, in the form of a mountain range.
Scientists have thought that the Earth’s mountain ranges are formed through this process over many millions of years. But MIT geologists have now found that the planet can generate new land far more quickly than previously thought.
In a paper published in the journal Geology, the team shows that parts of the Sierra Nevada mountain range in California rose up surprisingly fast, over a period of just 1.39 million years — more than twice as fast as expected for the region. The researchers attribute the rapid formation of land to a massive flare-up of magma.
“The really exciting thing about our findings is, with new high-precision geochronology, we were able to date how quickly that crust-building process happened, and we showed that this large volume of new crust was emplaced at an extremely rapid rate,” says the study’s lead author Benjamin Klein PhD ’19, who carried out the research as a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “It was sort of an instant. It was a little over 1 million years, but in geologic times, it was super fast.”
Klein’s co-authors are Associate Professor Oliver Jagoutz and Research Scientist Jahandar Ramezani, both in EAPS.
A complete cross-section
The Sierra Nevada mountain range is a product of the collision of two tectonic plates: the westward-moving North American Plate and what at the time was the Farallon Plate, which ground slowly under the North American Plate, eventually sliding entirely into the Earth’s mantle.
Around 100 million years ago, as both plates collided, they created first a chain of volcanos, then a towering mountain range that is today the Sierra Nevada.
“What is today the West Coast of the United States probably looked, back then, like the Andes today, with high elevations and a chain of large volcanos,” Klein says.
For their study, the researchers concentrated on a geologic feature in the Sierra Nevada known as an intrusive suite — a large volume of rock that originally formed deep in the Earth’s interior. Once crystallized, the rocks form a new, vertical column of continental crust.
They focused in particular on the Bear Valley Intrusive Suite, a unique formation in that it represents the vestiges of new continental crust that is today exposed on the surface, as a 40-mile stretch of granite. These rocks, which today lie horizontally along the mountain range, originally formed as a vertical column. Over time, this tower of new continental crust eroded, stretching and tilting into its current horizontal configuration.
“The Bear Valley Intrusive Suite gives us a complete cross-section of what these magma plumbing systems underlying large volcanos looked like, where normally we would have a limited snapshot,” Klein says. “That allows us to think much more completely about how quickly new crust was being built.”
A speed limit for new crust
The team collected rock samples across a region of the Sierra Nevada Batholith and brought them back to MIT to analyze their composition. They were able to determine the age of nine samples, using uranium-lead geochronology, a high-precision dating technique pioneered by the late MIT Professor Emeritus Sam Bowring. From each sample, the researchers isolated individual grains of zircon, a common mineral in rocks that contains uranium and some lead, the ratio of which scientists can measure to get an estimate of the rock’s age.
From their analyses, Klein and his colleagues discovered that the age of all nine samples spanned a surprisingly short range, of just 1.39 million years. The team calculated an estimate for the amount of magma that must have crystallized to form the new crust that the samples represent. They found that about 250 cubic kilometers of magma likely rose up from Earth’s interior and transformed into new crust — in just 1.39 million years.
“That’s about two-and-a-half times faster than previous estimates for crust formation in the Sierras, which is a pretty big difference,” Klein says. “It gives us a maximum speed limit for how quickly these things can actually happen.”
Klein says that given the speed of this new crust formation, the likely cause was a magma flareup, or sudden burst of magmatic activity.
“The entire batholith was constructed in almost 200 million years, but we know over that period of time, there were periods when it was highly active and periods that were quieter, with less new material added,” Klein says. “What we were able to show in this area was that, at least locally, the rate at which magma was brought in is much faster than the average rates that have been documented in the Sierras.”
Geologists have thought that magma flare-ups occur as a result of unusual activity in the Earth, such as tectonic plates suddenly colliding at a faster rate. According to everything researchers have documented about the Bear Valley Intrusive Suite, however, no such activity transpired at the time the mountain range formed.
“There’s no obvious trigger,” Klein says. “The system is pretty much going along, and then we see this big burst of magma. So this challenges some basic notions in the field, and should inform how people think of how quickly these things could be happening today, in places like the Andes or the volcanos in Japan.”
This research was supported, in part, by the National Science Foundation. More

It’s an amazing moment when a topic learned in the classroom comes to life. For senior Darya Guettler, that moment came on a sweltering day while installing solar panels in low-income communities in Los Angeles, alongside workers who had been previously incarcerated.
Guettler was volunteering with an MIT Energy Initiative program called Solar Spring Break, which had partnered with Homeboy Industries, an organization that supports formerly incarcerated individuals through career opportunities in green energy. Drilling the panels into the roofs while sweat dripped down her neck, Guettler finally got a chance to see the utility of solar panels in action. When the volunteers switched on the lights, the members of the community got together and celebrated.
“I’ve never done that before, and it was a very unique experience,” Guettler says, recalling the internship. “As students, we’re usually designing the solar panels. Actually installing them and then turning the power on — it’s like all these families now have power for free and can finally run their air conditioning during the day. It made it all feel real.”
Guettler’s fascination with renewable energy began back in high school geography class. Listening to lectures on fuel scarcity, she wondered why renewable energy sources weren’t more widely implemented. Her curiosity encouraged her to research solar panel efficiency and galvanic cell temperature concentrations.
She arrived at MIT with the goal of mitigating climate change through technological innovation, and soon joined the MIT Undergraduate Energy Club, where she says she met inspiring and equally passionate students. Over time, they helped to shape her mindset about what her role could be in helping with the climate crisis. Now the club’s president, Guettler has been working to expand the club’s education outreach programs and encourage kids to get excited about ways they can use engineering to help the planet.
Although Guettler had long understood the need to improve solar technologies, it wasn’t until her Solar Spring Break experience that she made the connection between climate change and the need to involve many different parties in putting together solutions.
“After that, I was kind of hooked on the policy side as well, because I saw that there’s really a space for combining all these things,” she says. “Now all of a sudden it wasn’t just about employing the technology, which I had always been interested in, but also about who was going to be employing it, where it was going to be placed, and how we could make that process as equitable as possible.”
Guettler decided to combine her mechanical engineering major with a degree in political science and has gravitated to classes focused on the intersection of sustainable technologies and climate policy.
“They’re really interesting classes. I’ve got a class about engineering democratic development, one about election modeling, and one in energy storage,” she says. “Honestly, sometimes it’s hard to pick. There’s so many I want to take!”
But of all her classes, one that Guettler is most looking forward to now is her capstone for mechanical engineering, 2.s009 (Explorations in Product Design). The class — which this year challenges students to create social impact projects centered around kindness — begins by placing students into groups and giving them a budget. The groups then design a product and come up with a prototype and a business pitch for it.
“The kindness aspect is pretty much up to the group to decide,” Guettler explains. “It can a project centered around climate change, environmental protection, helping people with disabilities, assisting marginalized communities — I’m super excited to see what people come up with.”
Guttler spent the past summer working in consulting, and in her spare time taught middle and high school students about climate change from her remote cabin in Maine. The classes were taught through MIT Splash, which allows MIT students to teach any topic of their choice to interested younger students.
“It was all online, but it was really fun,” she says. “We just kind of talked about climate models and used this cool tool where you can adjust different policy factors and just see what happens. The kids had so many questions, and I loved getting to build their interest and talk about it with them.”
Talking with people of all ages and backgrounds about ways we can develop a more sustainable future has been a consistent theme throughout Guettler’s experience at MIT. Last year, she visited West Point for the Student Conference on U.S. Affairs, where she spoke with military advisors and generals about the concerns of climate change from a national security perspective.
“I was really interested to see that climate change is also a really big issue to them too, since there’s a lot of bases near coastal waters that will be under threat when sea levels rise,” she says. “There’s definitely been a wide range of people I’ve interacted with about the climate change crisis, but at the end of the day, it’s always the same core concepts. I love hearing people’s different ideas, because more people means more potential solutions, and honestly, at this point, we need any solutions we can get.”
As an elected student to the MIT Committee on Outside Engagements, as well as a founding member of MIT Divest, Guettler hasn’t been shy about the importance of holding political leaders and officials accountable for their decisions.
“I was talking a lot with students to see what they held as important values and what they wanted MIT to represent. Climate action kept on coming up, which led to a bigger discussion of who MIT engages with.”
Her experience so far has been positive overall, and she notes that student representatives have been given a seat on MIT’s Climate Action Advisory Committee, as well as been able to contribute to the MIT Climate Action Plan. The inclusion has allowed students to advocate for ways MIT can take initiative to reduce and offset their energy emissions.
While Guettler recognizes that major institutions have the largest immediate impact on improving the climate crisis, she still wants everyone to recognize the importance of individual actions as well.
“My message to everyone right now is just go and vote, just please go and do that. I’ve been phone banking for different state races right now and people have been hanging up in my face or cursing me out, saying it’s not that serious. I’m like, are you serious?” she laughs. “I honestly think voting right now is the best thing you can do for the climate. Even if you’re feeling overwhelmed, even if you don’t feel like you can make an impact — you have an important decision that you can make. Now just go and vote for it!” More