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A primer for understanding climate science

Climate science and threats from climate change have been hot topics of conversation amongst the public as well as business and political leaders. And despite the fact that more than 90 percent of climate scientists attribute the majority of global mean temperature increase over the last few decades to human activity and warn that continued warming poses risks for mankind, doubt and misconceptions remain pervasive. This ultimately hampers efforts to improve the scientific field around climate and to develop effective solutions and policies to mitigate risks. 

Now, a primer from Kerry Emanuel, climate scientist and hurricane expert in the Department of Earth, Atmospheric and Planetary Sciences’ (EAPS) Program in Atmospheres, Oceans and Climate (PAOC), explains how climate metrics and dynamics are evaluated, and why climate action today is important for our future. Addressing some common questions about the field of study, Emanuel summarizes evidence for anthropogenic climate change, confronts some of the stickier questions behind uncertainty in climate projections, and discusses particular risks entailed by climate change and how they are quantified.

Emanuel worked with Larry Linden, an MIT alum and president of the Linden Trust, on how best to structure the scientific information and provide a socioeconomic case for climate action. Using accessible language, they decided to write it for an audience of intelligent nonscientists who want to learn more about the science.

“What he’s [Linden] really trying to do is to get business leaders in particular, and some political leaders like moderate republicans to advance this issue,” Emanuel says. “Larry thought it would be handy to have a climate primer to help people like these get the background they need to persuade others.”

Beginning with an overview of the scientific process, the primer provides a short history of climate science through the years and shows how carbon dioxide, a small molecule that makes up about 0.04 percent of the atmosphere by mass, could be responsible for Earth’s changing climate. Emanuel points to the greenhouse effect, trends in global mean temperature over Earth’s history, and the mechanisms underlying past climate change. He shows how evidence of certain weather patterns, ice, and ocean extent can be seen in the geologic record and ice cores, indicating past climate conditions, and explains how variables like changing sunlight and orbit cannot account for Earth’s recent, rapid warming.

While the past can help us understand paleoclimates and Earth cycles under certain conditions, it can only hint at what the future climate may look like. But technology helps narrow down the possibilities. The primer includes a discussion of climate models, their abilities and limitations, and how they are used to predict future climate change in the context of human activity. Lastly, the primer assesses direct risks from climate change to the United States like sea level rise, destabilization of food and water supplies, ocean acidification, and more strong storms, and acknowledges indirect risks like human conflict, immigration, and geopolitical destabilization. Emanuel explores how various levels of carbon dioxide emissions management and policy can mitigate some of the more damaging and costly outcomes of climate change.

“I want people to understand that the basic physics of climate have been known for well over 100 years, and to make the point that much of what we know about the climate system is based on simple physics and not as much on huge, complicated models that are often cited as the main basis for concern about climate,” Emanuel says. “I try to lay out in a simple and compact way the evidence that we are incurring substantial risk, and to talk quantitatively about what the risks are.”

But Emanuel didn’t want to his primer to be a picture wholly of doom and gloom, as that is not accurate, nor the best way to motivate action.

“Right now there’s a huge swath of people that believe that to solve this problem, we have to pay through the nose. … I don’t think they really understand the full range of options: what is new and exciting on the energy front and what the solutions really could be,” Emanuel says.  By painting a legitimately optimistic picture about viable climate and energy solutions, he thinks pessimism about the outcomes and resistance to the science fades away. And the strategy to get that to happen, he says, “may not involve that much climate science.”

“The object at this point in history is not so much to persuade people that we climate scientists are right as to persuade them that decarbonizing is in their own economic as well as environmental interest, and that the future of energy, far from being gloomy, is in fact very exciting,” he says.


School of Science welcomes three new professors this spring

This spring, the MIT School of Science welcomes three new professors in the departments of Brain and Cognitive Sciences, and Earth, Atmospheric and Planetary Sciences.

Michael Halassa aims to understand the neural basis of cognitive control and flexibility, particularly as it relates to attention and decision making. To study these questions, he has developed behavioral models of cognitive function in mice, allowing him to probe the underlying neural circuits and computations using parametric behavior, electrophysiological recordings, and causal manipulations. His major current focus is understanding the function of the thalamus, traditionally considered a relay station for sending sensory information to the cortex. Halassa is also a board-certified psychiatrist with fellowship training in psychotic disorders. Motivated by this clinical training, Halassa studies how the brain generates hypotheses about the world and how these hypotheses may be corrupted by disease processes such as schizophrenia. By developing perceptual tasks in animals that capture the underlying basic cognitive operations, Halassa aims to understand how the healthy brain generates such hypotheses and why the diseased brain has difficulty changing or revising them.

Halassa received an MD at the University of Jordan in 2004 and a PhD in neuroscience from the University of Pennsylvania in 2009. Following simultaneous appointments as a postdoctoral fellow in the laboratory of Matthew Wilson at MIT and as a resident in psychiatry at Massachusetts General Hospital, he joined the New York University faculty in 2014. Halassa joins the Department of Brain and Cognitive Sciences as an assistant professor and the McGovern Institute for Brain Research as an associate investigator.

Brent Minchew is a geophysicist working to understand the interactions between climate, the cryosphere, and the solid Earth. He uses a combination of geodetic observations — primarily interferometric synthetic aperture radar — and physical models to study dynamical systems and their various responses to environmental forcing. The bulk of Minchew’s research focuses on the dynamics of extant glaciers, with an emphasis on the mechanics of glacier beds, ice-ocean interactions, and ice rheology. By modulating ice flow and directly influencing glacier erosion rates, these factors play critical roles in glacier and ice sheet evolution, the dynamic response of glaciers to climate change, and the impact of glaciers on landform evolution and the global carbon cycle over human to geological timescales.

Minchew received BS and MS degrees in aerospace engineering from the University of Texas at Austin in 2008 and 2010. After completing his PhD in geophysics from the Caltech in 2016, he worked as a National Science Foundation postdoc with the Ice Dynamics and Paleoclimate Team at the British Antarctic Survey in the United Kingdom. Minchew joins the Department of Earth, Atmospheric and Planetary Sciences as an assistant professor.

Alexander “Sasha” Rakhlin works at the intersection of statistics, machine learning, and optimization. A major thrust of his research is in developing theoretical and algorithmic tools for online prediction, a method of machine learning that processes information provided in a sequential fashion. Rakhlin has uncovered critical connections between online prediction, optimization, and probability; these insights led to a fundamental theoretical understanding of the field as well as new efficient and accurate prediction methods. His contributions also include advances in statistical inference in structured problems, as well as new tools for optimal model selection. In newer lines of inquiry, Rakhlin developed a detailed analysis of statistical complexity of neural networks, offering insight into recent advances in deep learning.

Rakhlin received a BA in computer science and a BA in mathematics from Cornell University in 2000 and a PhD from MIT in 2006 under the direction of Tomaso Poggio. Following an appointment as a postdoc at the University of California at Berkeley, Rakhlin joined the faculty as an assistant professor at the University of Pennsylvania in 2009 with an appointment in the Department of Statistics at the Wharton School, and was promoted to associate professor with tenure in 2015. After spending a year as a visiting professor in the MIT Statistics and Data Science Center, Rakhlin joins the Department of Brain and Cognitive Sciences as an associate professor with tenure as well as the Institute for Data, Systems, and Society as a core faculty member.


Charting gas and oil's future in a decarbonizing world

When global oil prices declined dramatically in 2014 and 2015, leading energy analysts expected that oil production in the United States — consisting primarily of tight oil extracted from rock formations by means of massive hydraulic fracturing — would likewise decrease due to relatively high production costs. Despite the prospects for a negative return on investment, however, U.S. tight oil production continued almost unabated.

Perplexed by this development, a team of researchers sought to better understand the relationship between oil prices and production volumes. In particular, they aimed to pinpoint the factors that determine the breakeven points of tight oil production projects — essentially the oil price points at which revenue from sales equals the cost of production.

Though energy industry analysts have widely used breakeven costs to predict how oil producers will respond to changing market conditions and to assess the economic viability of proposed oil and gas development projects, they have routinely defined them imprecisely and inconsistently. This has resulted in predictions that have limited utility and reliability. To enable more robust predictions, the researchers — who work for Schlumberger-Doll Research, the MIT Joint Program on the Science and Policy of Global Change, the Atlantic Council, the King Abdullah Petroleum Studies and Research Center, and the Columbia University School of International and Public Affairs — have developed a systematic method to understand the costs of oil production and how they change with time and circumstances.

Applying this method, they have proposed a set of standard definitions for breakeven points at different stages of the oil production cycle. Their study appears in the journal Energy Economics.

“Instead of treating the economics of oil production as static, we realized that costs depend not only on technological change but also on supply chain optimization, the maturity of resource development, and even on the price of oil itself,” says lead author Robert L. Kleinberg, a Schlumberger Fellow based in Cambridge, Massachusetts. “Understanding the dynamic nature of the petroleum industry will help economists and policymakers more accurately predict how changes in supply and demand will affect this very important part of the world economy.” 

The research team first defined three primary categories of costs that are commonly referenced in breakeven analyses: lifting, half-cycle, and full-cycle. Lifting costs are expenditures required to produce oil from existing wells. Half-cycle costs include those related to drilling activity. Full-cycle costs include all expenses related to developing a new project, including exploration, resource estimation, and lease acquisition.

The researchers next showed how internal factors, such as technological improvements in the efficiency of oil extraction, and external factors, such as the market-determined price of oil, impact these costs. They noted that as oil prices decline, the main driver of break-even economics shifts from full-cycle to half-cycle to lifting costs. As oil prices rise, they found that the reverse sequence applies.

Looking closely at internal and external factors impacting the U.S. tight oil market, the researchers determined that much of the unexpected, rapid increase in U.S. tight oil production after 2010 was due to the availability of specialized oilfield equipment built during the previous six years to exploit shale gas. They also attributed the surprisingly slow decline of U.S. tight oil supplies that occurred while oil prices fell in 2014 and 2015 to the slow decline of field-level production from tight oil wells that were beyond their more prolific first year of production.

“Oil prices have a complicated impact on the dynamics of oil production, which in turn affects oil prices,” says Sergey Paltsev, a senior research scientist at the MIT Joint Program on the Science and Policy of Global Change and MIT Energy Initiative, and a co-author of the paper. “By taking a more systematic approach to defining break-even costs than previous studies, our analysis helps to construct more robust energy scenarios, enabling more accurate modeling of how the oil market is likely to react as the world shifts to more low-carbon energy sources.” 


Solar eclipse caused bow waves in Earth's atmosphere

The celebrated Great American Eclipse of August 2017 crossed the continental U.S. in 90 minutes, and totality lasted no longer than a few minutes at any one location. The event is well in the rear-view mirror now, but scientific investigation into the effects of the moon’s shadow on the Earth’s atmosphere is still being hotly pursued, and interesting new findings are surfacing at a rapid pace. These include significant observations by scientists at MIT’s Haystack Observatory in Westford, Massachusetts.

Eclipses are not particularly rare, but it is unusual for one to cross the entire continental U.S. as happened in August. By studying an eclipse’s effects on the electron content of the upper atmosphere, scientists are learning more about how our planet’s complex and interlocked atmosphere responds to space weather events, such as solar flares and coronal mass ejections, that can have severe effects on signal information and communication paths, and can impact navigation and positioning services.

The ionosphere is the layer of the atmosphere containing charged particles created primarily by solar radiation. It allows long-distance radio wave propagation and communication over the horizon and affects essential satellite-based transmissions in navigation systems and on-board aircraft. Since the ionosphere is the medium in which radio waves travel and is affected by solar variations, understanding its features is important for our modern technological society. The ionosphere is host to a huge number of naturally occurring waves, from small to large in size and strength, and eclipse shadows in particular can leave behind a large number of newly created waves as they travel across the planet.

One kind of these new waves, known as ionospheric bow waves, has been predicted for more than 40 years to exist in the wake of an eclipse passage. Researchers at MIT’s Haystack Observatory and the University of Tromsø in Norway confirmed the existence of ionospheric bow waves definitively for the first time during the August 2017 event. An international team led by Haystack Observatory scientists studied ionospheric electron content data collected by a network of more than 2,000 GNSS (Global Navigation Satellite System) receivers across the nation. Based on this work, Haystack’s Shunrong Zhang and colleagues published an article in December in the journal Geophysical Research Letters on the results showing the newly detected ionospheric bow waves.

Geospace research scientists at Haystack Observatory were able to observe the eclipse bow wave phenomenon for the first time in the atmosphere with unprecedented detail and accuracy, thanks to the vast network of extremely sensitive GNSS receivers now in place across the U.S. The observed ionospheric bow waves are much like those formed by a ship; the moon’s shadow travels so quickly that it causes a sudden temperature change as the atmosphere is rapidly cooled and then reheated as the eclipse passes. 

“The eclipse shadow has a supersonic motion which [generates] atmospheric bow waves, similar to a fast-moving river boat, with waves starting in the lower atmosphere and propagating into the ionosphere,” the description by Zhang and his colleagues states. “Eclipse passage generated clear ionospheric bow waves in electron content disturbances emanating from totality primarily over central/eastern United States. Study of wave characteristics reveals complex interconnections between the sun, moon, and Earth’s neutral atmosphere and ionosphere.”

GNSS receivers collect very accurate, high-resolution data on the total electron content (TEC) of the ionosphere. The rich detail provided by this data informed a separate study on eclipse effects in the same issue of Geophysical Research Letters by the Haystack research team and international colleagues. Haystack Observatory Associate Director and lead author Anthea Coster and her co-authors describe the continental size and timing of eclipse-triggered TEC depletions observed over the U.S. and observed increased TEC over the Rocky Mountains that is likely related to the generation of mountain waves in the lower atmosphere during the eclipse. The reason for this effect — which was not predicted or anticipated before the eclipse — is being investigated by the geospace science community.

“Since the first days of radio communications more than 100 years ago, eclipses have been known to have large and sometimes unanticipated effects on the ionized part of Earth’s atmosphere and the signals that pass through it,” says Phil Erickson, assistant director at Haystack and lead for the atmospheric and geospace sciences group. “These new results from Haystack-led studies are an excellent example of how much still remains to be learned about our atmosphere and its complex interactions through observing one of nature’s most spectacular sights — a giant active celestial experiment provided by the sun and moon. The power of modern observing methods, including radio remote sensors distributed widely across the United States, was key to revealing these new and fascinating features.”

The Haystack eclipse studies, including the bow wave observations, drew the attention of national science media outlets, including National Geographic, Newsweek, Gizmodo, and many others. One of Zhang’s readers, an eighth grader from Minnesota, asked some interesting questions:

Q: Was there any prior evidence to show that the waves would be arriving during the eclipse?

A: There were prior studies on the waves based on very limited spatial coverage of the observations. The Great American Eclipse provided unprecedented spatial coverage to view unambiguously the complete wave structures.

Q: Did these waves emit any seismic activity? Did they have a frequency that they could be detected on?

A: No, they didn’t. In fact we believe these waves were originated from the middle atmosphere [about 50 kilometers] but we observed them in the upper atmosphere at approximately 300 kilometers. They were very weak-pressure fluctuations if we observe the waves from the ground. This kind of wave was produced by eclipse-related cooling processes; there might be other ways to induce similar waves in the upper atmosphere.

Q: On the path of totality, were the waves stronger? Did they have any different effect anywhere else?

A: Yes, we found that they existed mostly along and within a few hundreds of kilometers from the totality central path. They were first seen in central U.S., then vanished in the central-eastern U.S. They were able to travel for about one hour at a speed of approximately 300 meters per second, slower than the moon shadow’s speed.

Haystack scientists will continue to analyze atmospheric data from the eclipse and expect to report other findings shortly. The next major eclipse across North America will occur in April 2024.

GPS TEC data products and access through the Madrigal distributed data system are provided to the community by MIT with support from U.S. National Science Foundation grant AGS-1242204 and NASA grant NNX17AH71G for eclipse scientific support.


Twelve School of Science faculty members appointed to named professorships

The School of Science has appointed 12 faculty members to named professorships.

The new appointments are:

Stephen Bell, the Uncas (1923) and Helen Whitaker Professor in the Department of Biology: Bell is a leader in the field of DNA replication, specifically in the mechanisms controlling initiation of chromosome duplication in eukaryotic cells. Combining genetics, genomics, biochemistry, and single-molecule approaches, Bell has provided a mechanistic picture of the assembly of the bidirectional DNA replication machine at replication origins.

Timothy Cronin, the Kerr-McGee Career Development Professor in the Department of Earth, Atmospheric and Planetary Sciences: Cronin is a climate physicist interested in problems relating to radiative‐convective equilibrium, atmospheric moist convection and clouds, and the physics of the coupled land‐atmosphere system.

Nikta Fakhri, the Thomas D. and Virginia W. Cabot Professor in the Department of Physics: Combining approaches from physics, biology, and engineering, Fakhri seeks to understand the principles of active matter and aims to develop novel probes, such as single-walled carbon nanotubes, to map the organization and dynamics of nonequilibrium heterogeneous materials.

Robert Griffin, the Arthur Amos Noyes Professor in the Department of Chemistry: Griffin develops new magnetic resonance techniques to study molecular structure and dynamics and applies them to interesting chemical, biophysical, and physical problems such as the structure of large enzyme/inhibitor complexes, membrane proteins, and amyloid peptides and proteins.

Jacqueline Hewitt, the Julius A. Stratton Professor in Electrical Engineering and Physics in the Department of Physics: Hewitt applies the techniques of radio astronomy, interferometry, and image processing to basic research in astrophysics and cosmology. Current topics of interest are observational signatures of the epoch of reionization and the detection of transient astronomical radio sources, as well as the development of new instrumentation and techniques for radio astronomy.

William Minicozzi, the Singer Professor of Mathematics in the Department of Mathematics: Minicozzi is a geometric analyst who, with colleague Tobias Colding, has resolved a number of major results in the field, among them: proof of a longstanding S.T. Yau conjecture on the function theory on Riemannian manifolds, a finite-time extinction condition of the Ricci flow, and recent work on the mean curvature flow.  

Aaron Pixton, the Class of 1957 Career Development Professor in the Department of Mathematics: Pixton works on various topics in enumerative algebraic geometry, including the tautological ring of the moduli space of algebraic curves, moduli spaces of sheaves on 3-folds, and Gromov-Witten theory. 

Gabriela Schlau-Cohen, the Thomas D. and Virginia W. Cabot Professor in the Department of Chemistry: Schlau-Cohen’s research employs single-molecule and ultrafast spectroscopies to explore the energetic and structural dynamics of biological systems. She develops new methodology to measure ultrafast dynamics on single proteins to study systems with both sub-nanosecond and second dynamics. In other research, she merges optical spectroscopy with model membrane systems to provide a novel probe of how biological processes extend beyond the nanometer scale of individual proteins.

Alexander Shalek, the Pfizer Inc.-Gerald Laubach Career Development Professor in the Department of Chemistry: Shalek studies how our individual cells work together to perform systems-level functions in both health and disease. Using the immune system as his primary model, Shalek leverages advances in nanotechnology and chemical biology to develop broadly applicable platforms for manipulating and profiling many interacting single cells in order to examine ensemble cellular behaviors from the bottom up.

Scott Sheffield, the Leighton Family Professor in the Department of Mathematics: Sheffield is a probability theorist, working on geometrical questions that arise in such areas as statistical physics, game theory and metric spaces, as well as long-standing problems in percolation theory.

Susan Solomon, the Lee and Geraldine Martin Professor in Environmental Studies in the Department of Earth, Atmospheric and Planetary Sciences: Solomon focuses on issues relating to both atmospheric climate chemistry and climate change, and is well-recognized for her insights in explaining the cause of the Antarctic ozone “hole” as well as her research on the irreversibility of global warming linked to anthropogenic carbon dioxide emissions and on the influence of the ozone hole on the climate of the southern hemisphere.

Stefani Spranger, the Howard S. (1953) and Linda B. Stern Career Development Professor in the Department of Biology: Spranger studies the interactions between cancer and the immune system with the goal of improving existing immunotherapies or developing novel therapeutic approaches. Spranger seeks to understand how CD8 T cells, otherwise known as killer T cells, are excluded from the tumor microenvironment, with a focus on lung and pancreatic cancers.


Susan Solomon awarded the 2018 Crafoord Prize

Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies at MIT, has been awarded the 2018 Crafoord Prize.

Announced today, Solomon is being honored “for fundamental contributions to understanding the role of atmospheric trace gases in Earth’s climate system.”

For more than 30 years, Solomon’s studies have been at the absolute forefront of research into the ozone layer and its role in the Earth’s climate system, with the chemical reactions she proposed now one of the cornerstones of stratospheric chemical modeling.

Now, together with fellow legendary climate scientist Syukuro Manabe of Princeton University, who has also played a dominant role in climate research over multiple decades, Solomon is being rewarded with this year’s Sweden’s Crafoord Prize in Geosciences, worth 6 million kronor, for contributing decisive knowledge to aid in combating one of the greatest challenges of our time.

Solomon is internationally recognized as a leader in atmospheric science, particularly for her insights in explaining the cause of the Antarctic ozone “hole.”

In the 1980s, Solomon solved the puzzle of the Antarctic ozone hole’s appearance, using theoretical and chemical measurement-focused studies in the Antarctic atmosphere. She examined the ice crystals in the stratospheric clouds that form there every year due to the extreme cold. These ice crystals cause the initiation of chemical processes that differ from those that were previously assumed to occur. On this basis, Solomon presented a theory that explained the link between manmade chlorofluorocarbon (CFC) emissions and the chemical processes taking place in the Antarctic stratosphere in the early spring — ones that led to the extensive depletion of its ozone layer. Her theory was verified by the results of the measurements conducted in the stratosphere. Later, Solomon showed how the thickness of the ozone layer in the southern hemisphere affects atmospheric flows and temperatures all the way down to ground level.

Subsequently, she and her colleagues have made multiple important contributions to understanding chemistry/climate coupling, including leading research on the irreversibility of global warming linked to anthropogenic carbon dioxide emissions, and on the influence of the ozone hole on the climate of the southern hemisphere. Her current focus is on issues relating to both atmospheric chemistry and climate change.

The Crafoord Prize is awarded in partnership between the Royal Swedish Academy of Sciences and the Crafoord Foundation, with the academy responsible for selecting the Crafoord Laureates. Awards are presented in one of four disciplines each year: mathematics and astronomy, geosciences, biosciences, or polyarthritis (such as rheumatoid arthritis). Awarded are chosen to complement those of the Nobel Prizes.

Professor Solomon will travel to Sweden to give her prize lecture at Lund University on May 22, and receive her prize at the Royal Swedish Academy of Sciences on May 24, in the presence of H. M. King Carl XVI Gustaf and H. M. Queen Silvia of Sweden.

Former professor in the Department of Earth, Atmospheric and Planetary Sciences (EAPS) Edward N. Lorenz (together with Henry Stommel) received the first Crafoord Prize in Geoscience in 1983. Former EAPS geosciences professor Peter Molnar was awarded the prize in 2014.


NIH’s All of Us Research Program partners with the National Library of Medicine to reach communities through local libraries

NIH’s All of Us Research Program and the National Library of Medicine (NLM) have teamed up to raise awareness about the program, a landmark effort to advance precision medicine. Through this collaboration, the National Network of Libraries of Medicine has received a $4.5 million award to support community engagement efforts by public