Environment

PhD student Jessica Varner traces the way synthetic building materials have transformed our environment. More

At least twice in Earth’s history, nearly the entire planet was encased in a sheet of snow and ice. These dramatic “Snowball Earth” events occurred in quick succession, somewhere around 700 million years ago, and evidence suggests that the consecutive global ice ages set the stage for the subsequent explosion of complex, multicellular life on Earth.
Scientists have considered multiple scenarios for what may have tipped the planet into each ice age. While no single driving process has been identified, it’s assumed that whatever triggered the temporary freeze-overs must have done so in a way that pushed the planet past a critical threshold, such as reducing incoming sunlight or atmospheric carbon dioxide to levels low enough to set off a global expansion of ice.
But MIT scientists now say that Snowball Earths were likely the product of “rate-induced glaciations.” That is, they found the Earth can be tipped into a global ice age when the level of solar radiation it receives changes quickly over a geologically short period of time. The amount of solar radiation doesn’t have to drop to a particular threshold point; as long as the decrease in incoming sunlight occurs faster than a critical rate, a temporary glaciation, or Snowball Earth, will follow.
These findings, published today in the Proceedings of the Royal Society A, suggest that whatever triggered the Earth’s ice ages most likely involved processes that quickly reduced the amount of solar radiation coming to the surface, such as widespread volcanic eruptions or biologically induced cloud formation that could have significantly blocked out the sun’s rays. 
The findings may also apply to the search for life on other planets. Researchers have been keen on finding exoplanets within the habitable zone — a distance from their star that would be within a temperature range that could support life. The new study suggests that these planets, like Earth, could also ice over temporarily if their climate changes abruptly. Even if they lie within a habitable zone, Earth-like planets may be more susceptible to global ice ages than previously thought.
“You could have a planet that stays well within the classical habitable zone, but if incoming sunlight changes too fast, you could get a Snowball Earth,” says lead author Constantin Arnscheidt, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “What this highlights is the notion that there’s so much more nuance in the concept of habitability.”
Arnscheidt has co-authored the paper with Daniel Rothman, EAPS professor of geophysics, and co-founder and co-director of the Lorenz Center.
A runaway snowball
Regardless of the particular processes that triggered past glaciations, scientists generally agree that Snowball Earths arose from a “runaway” effect involving an ice-albedo feedback: As incoming sunlight is reduced, ice expands from the poles to the equator. As more ice covers the globe, the planet becomes more reflective, or higher in albedo, which further cools the surface for more ice to expand. Eventually, if the ice reaches a certain extent, this becomes a runaway process, resulting in a global glaciation.

Global ice ages on Earth are temporary in nature, due to the planet’s carbon cycle. When the planet is not covered in ice, levels of carbon dioxide in the atmosphere are somewhat controlled by the weathering of rocks and minerals. When the planet is covered in ice, weathering is vastly reduced, so that carbon dioxide builds up in the atmosphere, creating a greenhouse effect that eventually thaws the planet out of its ice age.
Scientists generally agree that the formation of Snowball Earths has something to do with the balance between incoming sunlight, the ice-albedo feedback, and the global carbon cycle.
“There are lots of ideas for what caused these global glaciations, but they all really boil down to some implicit modification of solar radiation coming in,” Arnscheidt says. “But generally it’s been studied in the context of crossing a threshold.”
He and Rothman had previously studied other periods in Earth’s history where the speed, or rate at which certain changes in climate occurred had a role in triggering events, such as past mass extinctions.
“In the course of this exercise, we realized there was an immediate way to make a serious point by applying such ideas of rate-induced tipping, to Snowball Earth and habitability,” Rothman says.
“Be wary of speed”
The researchers developed a simple mathematical model of the Earth’s climate system that includes equations to represent relations between incoming and outgoing solar radiation, the surface temperature of the Earth, the concentration of carbon dioxide in the atmosphere, and the effects of weathering in taking up and storing atmospheric carbon dioxide. The researchers were able to tune each of these parameters to observe which conditions generated a Snowball Earth.
Ultimately, they found that a planet was more likely to freeze over if incoming solar radiation decreased quickly, at a rate that was faster than a critical rate, rather than to a critical threshold, or particular level of sunlight. There is some uncertainty in exactly what that critical rate would be, as the model is a simplified representation of the Earth’s climate. Nevertheless, Arnscheidt estimates that the Earth would have to experience about a 2 percent drop in incoming sunlight over a period of about 10,000 years to tip into a global ice age.
“It’s reasonable to assume past glaciations were induced by geologically quick changes to solar radiation,” Arnscheidt says.
The particular mechanisms that may have quickly darkened the skies over tens of thousands of years is still up for debate. One possibility is that widespread volcanoes may have spewed aerosols into the atmosphere, blocking incoming sunlight around the world. Another is that primitive algae may have evolved mechanisms that facilitated the formation of light-reflecting clouds. The results from this new study suggest scientists may consider processes such as these, that quickly reduce incoming solar radiation, as more likely triggers for Earth’s ice ages.
“Even though humanity will not trigger a snowball glaciation on our current climate trajectory, the existence of such a ‘rate-induced tipping point’ at the global scale may still remain a cause for concern,” Arnscheidt points out. “For example, it teaches us that we should be wary of the speed at which we are modifying Earth’s climate, not just the magnitude of the change. There could be other such rate-induced tipping points that might be triggered by anthropogenic warming. Identifying these and constraining their critical rates is a worthwhile goal for further research.”
This research was funded, in part, by the MIT Lorenz Center.

Topics: Climate, Geology, Climate change, Exoplanets, EAPS, Earth and atmospheric sciences, Environment, Mathematics, Planetary science, Research, School of Science More

With a founding $25 million gift from King Philanthropies, MIT’s Abdul Latif Jameel Poverty Action Lab (J-PAL) is launching a new initiative to solve problems at the nexus of climate change and global poverty.
The new program, the King Climate Action Initiative (K-CAI), was announced today by King Philanthropies and J-PAL, and will start immediately. K-CAI plans to rigorously study programs reducing the effects of climate change on vulnerable populations, and then work with policymakers to scale up the most successful interventions.
“To protect our well-being and improve the lives of people living in poverty, we must be better stewards of our climate and our planet,” says Esther Duflo, director of J-PAL and the Abdul Latif Jameel Professor of Poverty Alleviation and Development Economics at MIT. “Through K-CAI, we will work to build a movement for evidence-informed policy at the nexus of climate change and poverty alleviation similar to the movement J-PAL helped build in global development. The moment is perhaps unique: The only silver lining of this global pandemic is that it reminds us that nature is sometimes stronger than us. It is a moment to act decisively to change behavior to stave off a much larger catastrophe in the future.”
K-CAI constitutes an ambitious effort: The initiative intends to help improve the lives of at least 25 million people over the next decade. K-CAI will announce a call for proposals this summer and select its first funded projects by the end of 2020.
“We are short on time to take action on climate change,” says Robert King, co-founder of King Philanthropies. “K-CAI reflects our commitment to confront this global crisis by focusing on solutions that benefit people in extreme poverty. They are already the hardest hit by climate change, and if we fail to act, their circumstances will become even more dire.”
There are currently an estimated 736 million people globally living in extreme poverty, on as little as $1.90 per day or less. The World Bank estimates that climate change could push roughly another 100 million into extreme poverty by 2030.
As vast as its effects may be, climate change also presents a diverse set of problems to tackle. Among other things, climate change, as well as fossil-fuel pollution, is expected to reduce crop yields, raise food prices, and generate more malnutrition; increase the prevalence of respiratory illness, heat stress, and numerous other diseases; and increase extreme weather events, wiping out homes, livelihoods, and communities.
With this in mind, the initiative will focus on specific projects within four areas: climate change mitigation, to reduce carbon emissions; pollution reduction; adaptation to ongoing climate change; and shifting toward cleaner, reliable, and more affordable souces of energy. In each area, K-CAI will study smaller-scale programs, evaluate their impact, and work with partners to scale up the projects with the most effective solutions.
Projects backed by J-PAL have already had an impact in these areas. In one recent study, J-PAL-affiliated researchers found that changing the emissions audit system in Gujarat, India, reduced industrial-plant pollution by 28 percent; the state then implemented the reforms. In another study in India, J-PAL affiliated researchers found that farmers using a flood-resistant rice variety called Swarna-Sub1 increased their crop yields by 41 percent.
In Zambia, a study by researchers in the J-PAL network showed that lean-season loans for farmers increased agricultural output by 8 percent; in Uganda, J-PAL affiliated researchers found that a payment system to landowners reduced deforestation by 5 percent and is a cost-effective way to lower carbon emissions.
Other J-PAL field experiments in progress include one providing cash payments that stop farmers in Punjab, India, from burning crops, which generates half the air pollution in Delhi; another implementing an emissions-trading plan in India; and a new program to harvest rainwater more effectively in Niger. All told, J-PAL researchers have evaluated over 40 programs focused on climate, energy, and the environment.
By conducting these kinds of field experiments, and implementing some widely, K-CAI aims to apply the same approach J-PAL has directed toward multiple aspects of poverty alleviation, including food production, health care, education, and transparent governance.
A unique academic enterprise, J-PAL emphasizes randomized controlled trials to identify useful poverty-reduction programs, then works with governments and nongovernmental organizations to implement them. All told, programs evaluated by J-PAL affiliated researchers and found to be effective have been scaled up to reach 400 million people worldwide since the lab’s founding in 2003.
“J-PAL has distinctive core competencies that equip it to achieve outsized impact over the long run,” says Kim Starkey, president and CEO of King Philanthropies. “Its researchers excel at conducting randomized evaluations to figure out what works, its leadership is tremendous, and J-PAL as an organization has a rare, demonstrated ability to partner with governments and other organizations to scale up proven interventions and programs.”
K-CAI aims to conduct an increasing number of field experiments over the initial five-year period and focus on implementing the highest-quality programs at scale over the subsequent five years. As Starkey observes, this approach may generate increasing interest from additional partners.
“There is an immense need for a larger body of evidence about what interventions work at this nexus of climate change and extreme poverty,” Starkey says. “The findings of the King Climate Action Initiative will inform policymakers and funders as they seek to prioritize opportunities with the highest impact.”
King Philanthropies was founded by Robert E. (Bob) King and Dorothy J. (Dottie) King in 2016. The organization has a goal of making “a meaningful difference in the lives of the world’s poorest people” by developing and supporting a variety of antipoverty initiatives.
J-PAL was co-founded by Duflo; Abhijit Banerjee, the Ford International Professor of Economics at MIT; and Sendhil Mullainathan, now a professor at the University of Chicago’s Booth School of Business. It has over 200 affiliated researchers at more than 60 universities across the globe. J-PAL is housed in the Department of Economics in MIT’s School of Humanities, Arts, and Social Sciences.
Last fall, Duflo and Banerjee, along with long-time collaborator Michael Kremer of Harvard University, were awarded the Nobel Prize in economic sciences. The Nobel citation observed that their work has “dramatically improved our ability to fight poverty in practice” and provided a “new approach to obtaining reliable answers about the best ways to fight global poverty.”
K-CAI will be co-chaired by two professors, Michael Greenstone and Kelsey Jack, who have extensive research experience in environmental economics. Both are already affiliated researchers with J-PAL.
Greenstone is the Milton Friedman Distinguished Service Professor in Economics at the University of Chicago. He is also director of the Energy Policy Institute at the University of Chicago. Greenstone, who was a tenured faculty member in MIT’s Department of Economics from 2003 to 2014, has published high-profile work on energy access, the consequences of air pollution, and the effectiveness of policy measures, among other topics.
Jack is an associate professor in the Bren School of Environmental Science and Management at the University of California at Santa Barbara. She is an expert on environment-related programs in developing countries, with a focus on incentives that encourage the private-sector development of environmental goods. Jack was previously a faculty member at Tufts University, and a postdoc at MIT in 2010-11, working on J-PAL’s Agricultural Technology Adoption Initiative. More

As the air cleared after lockdowns, solar installations in Delhi produced 8 percent more power, study shows. More

Like most offices across MIT, the Office of Sustainability (MITOS) has in recent months worked to pivot projects while seeking to understand and participate in the emergence of a new normal as the result of the Covid-19 pandemic. Despite now working off campus, the MITOS team methodology — one that warrants collective engagement, commitment to innovative problem solving, and robust data collection — has continued.
An expanded look at resiliency
When the MIT community transitioned off campus, many began to use the word “resilient” for good reason — it’s one way to describe a community of thousands that quickly learned how to study, research, work, and teach from afar in the face of a major disruption. In the field of sustainability, resiliency is frequently used when referring to how communities can not only continue to function, but thrive during and after flooding or extreme heat events as the result of climate change.
In recent months, the term has taken on expanded meaning. “The challenges associated with Covid-19 and its impact on MIT and the greater community has provided a moment to explore what a sustainable, resilient campus and community looks like in practice,” says Director of Sustainability Julie Newman.
The MIT campus climate resiliency framework codified by MITOS — and in response to a changing climate — has long been organized around the interdependencies of four core systems: community (academic, research, and student life), buildings, utilities, and landscape systems. This same framework is now being applied in part to the MIT response to Covid-19. “The MIT campus climate resiliency framework has enabled us to understand the vulnerabilities and capacities within each core system that inhibit or enable fulfillment of MIT’s mission,” explains Brian Goldberg, MITOS assistant director. “The pandemic’s disruption of the community layer provides us with a remarkable test in progress of this adaptive capacity.”
The campus response to the pandemic has, in fact, informed future modeling and demonstrated how the community can advance its important work even when displaced. “MIT has been able to offer countless virtual resources to maintain a connected community,” Goldberg explains. “While a future major flood could physically displace segments of our community, we’ve now seen that the ability to quickly evacuate and regroup virtually demonstrates a remarkable adaptive capacity.”
Taking the hive home
Also resilient are the flowering plants growing in the Hive Garden — the Institute’s student-supported pollinator garden. Maintained by MIT Grounds Services alongside students, the closure of campus meant many would miss the first spring bloom in the new garden. To make up for this, a group of UA Sustainability Committee (UA Sustain) students began to brainstorm ways to bring sustainable gardening to the MIT community if they couldn’t come to campus. Working with MITOS, students hatched the idea for the Hive@Home — a project that empowers students and staff to try their hands (and green thumbs) at growing a jalapeno or two, while building community.
“The Hive@Home is designed to link students and staff through gardening — continuing to strengthen the relationships built between MIT Grounds and the community since the Hive Garden started,” says Susy Jones, senior project manager who is leading the effort for MITOS. With funding from UA Sustain and MindHandHeart, the Hive@Home pilot launched in April with more than four dozen community members receiving vegetable seeds and growing supplies. Now the community is sharing their sprouts and lessons learned on Slack with guidance from MIT Grounds experts like Norm Magnusson and Mike Seaberg, who helped bring the campus garden to life, along with professor of ocean and mechanical engineering Alexandra Techet, who is also an experienced home gardener.
Lessons learned from Covid-19 response 
The impacts of Covid-19 continue to provide insights into community behavior and views. Seeing an opportunity to better understand these views, the Sustainability Leadership Committee, in collaboration with the Office of Sustainability, the Environmental Solutions Initiative, Terrascope, and the MIT Energy Initiative, hosted a community sustainability forum where more than 100 participants — including staff, students, and faculty — shared ideas on how they thought the response to Covid-19 could inform sustainability efforts at MIT and beyond. Common themes of human health and well-being, climate action, food security, consumption and waste, sustainability education, and bold leadership emerged from the forum. “The event gave us a view into how MIT can be a sustainability leader in a post Covid-19 world, and how our community would like to see this accomplished,” says Newman.
Community members also shared a renewed focus on the impacts of consumption and single-use plastics, as well as the idea that remote work can decrease the carbon footprint of the Institute. The Sustainability Leadership Committee is now working to share these insights to drive action and launch new ideas with sustainability partners across campus. 
These actions are just the beginning, as plans for campus are updated and the MIT community learns and adapts to a new normal at MIT. “We are looking at these ideas as a starting place,” explains Newman. “As we look to a future return to campus, we know the sustainability challenges and opportunities faced will continue to shift thinking about our mobility choices, where we eat, what we buy, and more. We will continue to have these community conversations and work across campus to support a sustainable, safe MIT.” More

It’s not a typical sentence you’d find on a class schedule, but on April 2, the first action item for one MIT course read: “Check in on each other’s health and well-being.” The revised schedule was for Susan Murcott and Julie Simpson’s spring D-Lab class EC.719 / EC.789 (Water, Climate Change, and Health), just one of […] More

MIT’s Deshpande Center for Technological Innovation hosted IdeaStream, an annual showcase of technologies being developed across MIT, online for the first time in the event’s 18-year history. Last month, more than 500 people worldwide tuned in each day to view the breakthrough research and to chat with the researchers. Speakers from 19 MIT teams that […] More

From above, Antarctica appears as a massive sheet of white. But if you were to zoom in, you would find that an ice sheet is a complex and dynamic system. In the Department of Earth, Atmospheric and Planetary Sciences (EAPS), graduate student Meghana Ranganathan studies what controls the speed of ice streams — narrow, fast-flowing […] More