By Clarisse Hart, Harvard Forest Communications
A new study led by archaeologists, ecologists, and paleoclimatologists at Harvard and elsewhere overturns long-held beliefs about the role humans played in shaping the American landscape before and after European colonization. The findings offer insights and lessons in managing biodiverse landscapes in the Northeast.
The study, published today in the journal Nature Sustainability, focuses on the coast from Long Island to Cape Cod and the nearby islands of Nantucket, Martha’s Vineyard, Block Island, and Naushon — areas that historically supported the densest populations of native peoples in New England and today are home to the highest concentrations of rare habitats in the region, including sandplain grasslands, heathlands, and pitch pine and scrub oak forests.
“For decades, there’s been a growing popularization of the interpretation that for millennia, native people actively managed landscapes — clearing and burning forests, for example — to support horticulture, improve habitat for important plant and animal resources, and procure wood resources,” said study co-author David Foster, director of the Harvard Forest at Harvard University. These practices were credited with the creation of open-land habitats and enhanced regional biodiversity.
But, Foster said, the data reveal a new story. “Our data show a landscape that was dominated by intact, old-growth forests that were shaped largely by regional climate for thousands of years before European arrival.”
Fires were uncommon, and native people foraged, hunted, and fished without clearing much land, the research revealed. “Forest clearance and open grasslands and shrublands only appeared with widespread agriculture during the European colonial period within the last few hundred years,” said Wyatt Oswald, a professor at Emerson College and study lead author.
The researchers say the findings transform thinking about how landscapes have been shaped in the past and offer insights into how they might best be managed in the future. “Ancient native peoples thrived under changing forest conditions not by intensively managing them but by adapting to them and the changing environment,” noted archaeologist and study co-author Elizabeth Chilton, dean of Harpur College of Arts and Sciences at Binghamton University.
To reconstruct historical changes to the land, scientists combined archaeological records with more than two dozen intensive studies of vegetation, climate, and fire history spanning 10,000 years. They found that old-growth forests were predominant for millennia but are extremely uncommon today.
“Today New England’s species and habitat biodiversity are globally unique, and this research transforms our thinking and rationale for the best ways to maintain it,” said Oswald. “It also points to the importance of historical research to help us interpret modern landscapes and conserve them effectively into the future.
The authors also noted the unique role that Colonial agriculture played in shaping landscapes and habitat. “European agriculture, especially the highly varied activity of sheep and cattle grazing, hay production, and orchard and vegetable cultivation in the 18th and 19th centuries, made it possible for open-land wildlife species and habitats that are now rare or endangered — such as the New England cottontail — to thrive,” said Foster. Open-land species have declined dramatically as forests regrow on abandoned farmland, and housing and commercial development of both forests and farms have reduced their habitat.
Foster said that the unique elements of biodiversity initiated through historical activities can be encouraged through similar management practices today. “Protected wildland reserves would preserve interior forest species that were abundant before European settlement,” he said. “Lands managed through the diversified farming and forestry practices that created open lands and young forests during the Colonial period would support another important suite of rare plants and animals.”
For successful conservation models that leverage this historical perspective, the authors point to efforts by the Trustees of Reservations, the oldest land trust in the world, which manages more than 25,000 acres in Massachusetts that include old and young forests, farms, and many cultural resources. The organization, for instance, uses controlled livestock grazing to keep lands open for birds like bobolinks and meadowlarks.
By Deborah Blackwell, Arnold Arboretum Communications
When botanist Asa Gray hiked his way through Tennessee in 1843 searching for seeds of the rare piratebush to plant in the Harvard Botanic Garden, he could not have known that nearly 180 years later plant scientists from the other side of the world would retrace his steps.
But this fall, in a historic collaboration, The Arnold Arboretum of Harvard University welcomed Chinese botanists from the North America-China Plant Exploration Consortium (NACPEC) on a joint expedition to the Appalachian Mountains to collect seed from North American plants to grow in scientific plant collections in China.
Since NACPEC was founded in 1991, plant explorers from the Arboretum and other member institutions have traveled to China 18 times to collect seed, herbarium specimens, and plant DNA samples for study and conservation in North American collections. The Appalachian expedition in September, coordinated by Andrew Gapinski, head of horticulture at the Arboretum and chair of NACPEC, and Kang Wang, research horticulturist and director of education at the Beijing Botanical Garden, furthered the group’s mission of building international partnerships in support of the study and conversation of the world’s temperate flora.
Focusing on Appalachian flora, Wang and his colleagues Tao Deng of the Kunming Institute of Botany and Xinfen Gao of the Chengdu Institute of Biology created a list of target species to collect for their research and collections in China, including magnolias, ashes, and maples.
Gapinski and expedition colleagues Sean Halloran, Arboretum plant propagator; Jared Rubinstein, Arboretum Living Collections Fellow; and Angela Magnan from the U.S. National Arboretum compiled an additional list of 41 target taxa for the Arboretum, including piratebush — the oldest wild-collected plant at the Arboretum. Originated as seed collected by Gray in his 1843 expedition, piratebush was brought to the Arboretum from the Harvard Botanic Garden in 1946. Along with 400 other rare or endangered plants, it is part of the Arboretum’s Campaign for the Living Collections, a 10-year initiative to document, collect, and preserve plants, particularly those of critical conservation value.
The three-week expedition covered 3,500 miles through five states — Ohio, Kentucky, Tennessee, Georgia, and North Carolina. Each day, the plant collectors carried supplies and gear including eight-foot pole pruners, herbarium field presses, plant identification keys, and plenty of bug spray into field, and hiked through the thick forests of Appalachia. Along with local guides, the team forded the Red River in Daniel Boone National Forest to find seeds of an American sycamore, descended to the base of a waterfall in Georgia to collect buttonbush seeds, and climbed Roan Mountain — one of the highest points of the Appalachian Trail in Tennessee — for seeds of the rare green alder. Each collection involved recording information about the geology and plant communities of the site, harvesting and bagging fruits, and collecting branch samples to dry for herbarium vouchers.
The expedition offered both adventure and challenges for the collectors, including a steep, 10-mile hike in humid, 100-degree heat through the Walls of Jericho natural area in Tennessee, only to find that birds had eaten all but three fruits of their target, limerock arrowwood. But, in an echo of Gray’s 1843 expedition, they discovered dozens of piratebush plants laden with fruits along the Appalachian Trail in Cherokee National Forest, providing an opportunity for ex situ conservation of both of these endangered plant species.
It was victories like these that most excited Wang, Gao, and Deng.
“Alongside our NACPEC partners from the Arnold Arboretum we journeyed through one of the most biodiverse regions of the temperate world collecting plants that will soon be growing in the Beijing Botanical Garden, where millions of visitors will get to enjoy them,” Wang said. “Not only that, but generations of scientists will be able to study these collections in China, as they have been doing at the Arnold Arboretum since its founding.”
Gapinski said the partnerships represented by the expedition began a new chapter in the history of international plant collection.
“For nearly three decades NACPEC has worked to foster partnerships and undertake plant exploration to study and conserve the flora of China — possible only through the support of the Chinese Academy of Sciences, Beijing Botanical Garden, and the dedicated individuals involved,” he said. “Today, we seek to further cement this one-of-a-kind, reciprocal collaboration and to ensure that these relationships continue long into the future, with a new generation of participants and partnerships.”
In addition to seed collection, the expedition team collected and dried plant samples to deposit at the Chinese and North American herbaria, where they can be used to study evolution, physiology, and taxonomy. Collections from the trip will also be shared with the U.S. National Arboretum for the Woody Landscape Plant Germplasm Repository, as well as other NACPEC member gardens.
Arboretum Director William “Ned” Friedman joined the expedition in northern Georgia, returning to the state where he began his career as a professor at the University of Georgia.
“To be in the field with Kang, Xinfen, and Tao — literally an all-star botanical team from China — along with the Arboretum explorers was fantastic,” he said. “After all of the times that we have been so generously hosted in China, this felt like perfect way to deepen our sense of reciprocity and share some of the evolutionary bounty of North America with botanical garden visitors and researchers in China.”
Jared Rubinstein, Arnold Arboretum Living Collections Fellow, contributed to this article.
Image: Arnold Arboretum Director William "Ned" Friedman, Tao Deng, Xinfen Gao, and Kang Wang discuss how to prepare an herbarium voucher for a large blackjack oak. Sean Halloran/Arnold Arboretum
By Adam Zewe
(Photo by Eliza Grinnell/SEAS Communications)
At its height, Hurricane Dorian and its brutal, 185-mile-per-hour winds stretched more than 60,000 square miles, whipping an area of the Atlantic Ocean roughly the size of Georgia.
By comparison, the hurricane forming in front of Rachel Collins could fit comfortably inside a shoebox.
Standing safely on dry land inside a Harvard classroom, she was using a pump, tank, turntable, and tap water to “build” a miniature hurricane as a way to learn about the pressure gradient and Coriolis effect that characterize these devastating storms.
“Sometimes, when you just look at the math and the derivatives, it is hard to conceptualize how these things are related to the storms you see on TV,” said Collins, A.B. ’20, an earth and planetary science concentrator. “Seeing the physics in action like this makes it easier to understand.”
Using hands-on lab work to help students understand the physics of weather and fundamentals of climate is the centerpiece of Climate and Atmospheric Physics Laboratory (ESE 129), a new course at the Harvard John A. Paulson School of Engineering and Applied Sciences.
Taught by Marianna Linz, Assistant Professor of Environmental Science and Engineering and of Earth and Planetary Sciences, the course’s flipped classroom model challenges students to complete readings and problem sets independently and then tackle in-class synthesis assignments and labs that bring concepts to life.
“Essentially, we are studying fluids on a rotating planet. Rotating fluids are super-weird, incredibly non-intuitive, and extremely beautiful,” Linz said. “Weather systems develop because the earth is rotating, and you can get an analog for a rotating fluid system by using a tank that is rotating on a table. You can learn a ton of lessons from that, in terms of gaining intuition into how the atmosphere actually works.”
As their hurricane continued churning in the tank, Collins and lab mate Ella Necheles, A.B. ’21, an environmental science and engineering and applied math concentrator, began dropping tiny paper flecks into the water, keeping a careful eye on how their movement patterns changed as they approached the higher-pressure eye-wall of the hurricane.
They and their classmates experimented by angling the lab set ups, pouring pebbles into tanks to create more drag, or introducing temporary disturbances into the systems.
“It was fun to see how manipulating the factors influenced the shape or behavior of the drain. I also found this part really helpful in understanding how the different components, specifically height and pressure, related to the dynamics we were seeing,” Necheles said. “After seeing how we could relate the rotation speed to the pressure gradient, things really started to click.”
The hurricane lab was one of several hands-on sessions designed to help students grasp concepts that are difficult to explain with words and diagrams, Linz said. In another lab, students dropped a column of ice into the middle of water tanks to see how the earth’s cold poles and warm equator impact global circulation.
The course, which covers concepts in global warming, the greenhouse effect, weather systems, global circulation, and waves in the atmosphere, also focuses on modeling and data visualizations.
“It’s not something we talk about before we start doing research, but the plots in my first paper were terrible,” Linz said. “You learn so much over time, but I don’t think it is necessary to learn from doing it badly and having it published. The ability to think about how to visualize data will be relevant for STEM majors no matter where they go.”
The opportunity to develop better data visualization skills inspired Miles Wang to take ESE 129. While it has been challenging to grasp some of the complex equations, he has enjoyed the coding exercises, especially since he plans to pursue a data science career.
“The most poignant lesson I’ve learned so far is how the same data can be presented in vastly different ways to tell contradicting stories or messages,” said Wang, S.B. ’20, an electrical engineering concentrator. “For example, there was a data visualization that took real data to show that global warming wasn’t a real phenomenon. But we were able to understand what tools were used to make it look like it wasn’t real.”
For Wendy Wu, the weekly labs made ESE 129 an appealing change from lecture-style courses. She particularly enjoyed a field trip to a glass blowing studio, where students created paperweights to better understand the concept of black-body radiation (the energy emitted by all objects based on their temperature).
The reflectivity and absorptivity of glass varies greatly depending on its color, and students saw these differences “in action” as they heated and cooled the glass.
“The most surprising lesson I’ve learned has been the science behind precipitation and how difficult it is to predict precipitation,” said Wu, A.B. ’22, an environmental science and engineering concentrator. “By being able to examine different predictive models, I was able to better understand and sympathize with the unpredictability of weather forecasts.”
Having the ability to read a weather map and understand how the jet stream affects extreme weather events will help students be more informed citizens in a future that will be increasingly impacted by climate change, Linz said.
“I think it is important for everyone to understand global warming and climate from some perspective, whether that be physics or ethics,” she said.
Every year the publisher of the august Oxford English Dictionary peers into the zeitgeist and selects a “word of the year” whose sudden appearance or rising popularity tells us something about our collective mood or obsessions. The last three, for instance, have been toxic, youthquake, and post-truth. Take from those what you will.
This year’s word — in actuality a phrase — is “climate emergency.” The publisher Oxford Dictionaries said the choice was prompted by a 100-fold increase in usage over the previous year, a rise that reflected the rising heat of environmental activism and the growing guilt and angst over our role in the problem.
Along with climate emergency, Oxford selected a short list of other environment-related terms whose usage also grew noticeably. That includes some that will seem familiar to many — climate action, climate denial, climate crisis, net zero, extinction, and plant-based — and others newer to the tongue — eco-anxiety, ecocide, flight shame, and global heating, whose usage soared 18,358 percent.
The Gazette asked several Harvard faculty members if they thought “climate emergency” the mots justes for 2019 or whether another word or phrase might better characterize how the English-speaking world is feeling about climate and the environment.
‘There doesn’t have to only be one phrase. … What matters is that we keep talking.’
Director of the Center for Climate, Health, and the Global Environment; professor of the practice of public health
What I take away from this is that climate change has reached a turning point in the public consciousness. In 2019, people all over the world began demanding actions and solutions. We don’t have to worry so much about whether we use “climate emergency,” “climate crisis,” or “global heating.”
There doesn’t have to only be one phrase. What’s important is that we keep the conversation going at our dinner tables, at work, and at school. What matters is that we keep talking about climate change using a variety of angles to appeal to different audiences, whether it’s about water, technology, health, or kids, so that our leaders develop the political will to rapidly shift away from fossil fuels.
(Image: Rose Lincoln/Harvard file photo)
‘I’m really impressed with the interest — particularly of young people — in the problem.’
Gilbert Butler Professor of Environmental Studies; faculty chair of the Harvard China Project on Energy, Economy and Environment
It’s difficult to choose just one word — maybe “carbon zero,” “carbon negative.” If you believe that we have to limit temperature growth to 2 degrees or 1.5 degrees C, then you have to start thinking about essentially no fossil fuel use at all after 15 or 20 years. Even more than that, you have to start thinking about having negative carbon, in which you begin to draw carbon out of the atmosphere in order to avoid a problem.
The depressing thing is if you look at what the country commitments are in the Paris Agreement, even if all the countries did what they said they would do, this problem is going to get worse. So then the question is: What do you do about it?
I’ll continue to try to understand how you can make the transition as rapidly as possible to a zero-carbon future for countries such as the U.S., China, and India, the big players. I’ll also start thinking about some of the negative-carbon possibilities.
We had a paper six months or so ago that looked at harvesting crop waste, combining it with coal, and gasifying it to produce electricity, and then capturing the CO2 and burying it or using it. So that’s a way to think about negative-carbon possibilities.
On the other side, I’m really impressed with the interest — particularly of young people — in the problem. There’s also interest by our alumni groups. Alumni clubs around the country have started coming to the University saying, “We would like to have somebody come and talk about the climate issue.” The interest is really high.
As far as “carbon negative” goes, Al Gore has opened his family farm in Tennessee to people who want to do experiments on how you can capture and retain more carbon in soils. I think the way we can do it is using photosynthetic uptake of carbon and instead of having the carbon simply go back into the atmosphere, find ways to capture it and use it or bury it or sequester it.
Stopping unnecessary deforestation, reforesting areas that are not particularly productive, thinking about more conservative agricultural systems, and managing soils would be good ideas. You want to let the plants take carbon out of the atmosphere and then grab that carbon. But there’s no easy solution.
(Image: Harvard file photo)
‘The amount of action and momentum that this word cloud reflects is a cause for some real hope.’
Director of the Planetary Health Alliance; principal research scientist at the Harvard T.H. Chan School of Public Health
My general reaction is that this is a great word, but that the short list is very instructive as well. Because really the crisis is much broader than climate.
The growing use of these terms reflects an awakening recognition of core themes in the field of planetary health: that the scale of human activity has outstripped the capacity of our planet to absorb our wastes or provide the resources we are using. As a result, we are disrupting and transforming most of the natural systems on the planet including the climate system but also biodiversity (fueling the sixth mass extinction), global pollution of air, water, and soil, scarcity of fresh water and arable land, and deforestation. Hence other words like “extinction” crisis or “ecocide.”
These transformations interact with each other in complex ways to alter core conditions for human health and well-being: the quality and quantity of food we produce, the air we breathe, the water we can access, our exposure to infectious disease, the very habitability of our homes. They also impact our mental health, with “eco-anxiety” or “ecological grief” being one manifestation of those mental health effects.
One of the exciting developments this year has been a groundswell of activism and movement building to address this crisis, including the rise of Extinction Rebellion, the BirthStrike movement in the U.K., and the School Strike movement led by Greta Thunberg, among many, many others.These efforts have called out “climate denial” and the associated legislative capture by special interests that have prevented action for too long as part of addressing the “climate crisis” with “climate action.”
All of this activity and recognition of the urgency of the moment we find ourselves in has us thinking about what we can do differently, both individually and collectively, driving more attention to things like “flight shame,” “plant-based” diets, and “net-zero” emissions. The scale of the ecological and human crisis we face is pretty terrifying, but the amount of action and momentum that this word cloud reflects is a cause for some real hope.
(Image: Rose Lincoln/Harvard file photo)
‘More important than immediate action would be to have clear policies that are significant now, sustainable over the long term.’
Raymond Plank Research Professor of Global Energy Policy; research director of the Harvard Electricity Policy Group
My copy of Webster’s Dictionary defines an emergency as “a sudden, urgent, usually unexpected occurrence or occasion requiring immediate action.” Thus “climate emergency” is a misnomer.
The conversation about appropriate climate policy is more than three decades old. Given our best understanding of the science, it is going to be a problem the world will have to deal with for centuries to come. More important than immediate action would be to have clear policies that are significant now, sustainable over the long term, and clearly connected to the underlying facts.
One such policy, necessary but not sufficient, would be a material carbon price along the lines of the bipartisan proposal of the Climate Leadership Council. Promises that mandates for clean energy will be effective, quick, and cheap are unlikely to be fulfilled, and thus mislead.
Climate presents an example of a “wicked problem.” Real solutions are likely to be incomplete, slow, and expensive, but worth it.
(Image: Kris Snibbe/Harvard file photo)
‘To tackle this existential challenge we need to align all of our collective actions now.’
Director of the Harvard Forest
This is exactly the right term as it clearly articulates the focus on the problem and the immediacy of the need for action. Embedded in the word “climate” is the clear sense of the enormity and importance of the issue — global and yet affecting all forms of life — and the reality that any fix will necessarily require massive, long-term effort. But the word “emergency” conveys the reality that this issue cannot wait. To tackle this existential challenge we need to align all of our collective actions now.
I emphasize collective because a global emergency scales from the individual to the global community. Each of us has a role, in our lives, across the Harvard campus and neighborhoods, and at community, state, national, and international levels. That scaling works to our benefit. We can act individually and together to make Harvard and its backyard exemplars of the way forward for the world.
For Harvard, that means taking decisive action to act ethically based on clear science to stop supporting all entities that knowingly harm the environment, while also employing all of our research, education, and engagement to inform and lead in the world. Meanwhile, in Massachusetts and New England, Harvard can advance a sustainable landscape of wildlands, woodlands, farmlands, and communities.
(Image: Kris Snibbe/Harvard file photo)
‘It’s an emergency. Let’s call it one.’
John and Natty McArthur University Professor at the Harvard Business School
I love the choice of “climate emergency” as word of the year. There are the obvious reasons. Take the stream of headlines: fires in California; floods in the heartland; drought in the Southwest; the stream of reports from the world’s scientists, desperately trying to rouse the world to action; the Intergovernmental Panel on Climate Change on oceans and ice, on land, on the fact that we must limit warming to 1.5 degrees C, not 2, if we are to avoid the worst effects; the articles recalculating exactly how much of the world is likely to be under water by 2050. And this means doing the seemingly impossible — namely bringing emissions to zero in 30 years.
Then there are the less-obvious ones. The ones that are so intimate, so personal that it feels as though someone has put a hand around your heart and twisted, hard.
This spring I ran one of [MIT Professor] John Sterman’s excellent climate-change simulations. The students were divided into national blocs, charged with negotiating with each other in an attempt to put in place a global policy regime that would keep us reasonably cool. It’s a great simulation, and so it reproduced exactly what’s happening — they failed. I asked them to try harder, and they failed again.
At the end of the session, I asked the students to tell me what they had learned. One said that he had learned that unless and until we all agree to give something up, we will never solve climate change. Another put her hands on the swell of the child she was carrying and said, “But my son, my son will be only slightly older than I am now in 2050….”
It’s an emergency. Let’s call it one.
James J. McCarthy: January 25, 1944 – December 11, 2019
"For 40 years, Jim McCarthy was a central part of Harvard’s efforts on the environment. Jim’s own research on biological oceanography probed the nitrogen cycle in the oceans, seeking to understand how the ecology of plankton affected and was affected by nutrient cycling. But Jim’s impact went far beyond his own research. Jim promoted the best in all of us through his numerous leadership positions inside and outside of Harvard and also through his extraordinary devotion to students. Jim was Director of the Museum of Comparative Zoology for twenty years (1982–2002) and served as Pforzheimer House Master (with his wife, Sue) and Head Tutor for the Environmental Science and Public Policy Concentration. Outside of Harvard, Jim served as co-Chair of Working Group 2 (Climate Change Impacts) of the 3rd Assessment for the Intergovernmental Panel on Climate Change (IPCC), and as lead author for the Arctic Climate Assessment of 2004. Jim was President of the American Association for the Advancement of Science, Board Chair of the Union of Concerned Scientists, and a member of the U.S. Arctic Commission. He received the Tyler Prize for Environmental Achievement in 2018.
Beyond his numerous professional accomplishments, I am thankful for Jim’s friendship. For many who knew him, Jim was a gentle and caring colleague who cared about the people in his life. His curiosity and joy of the world was infectious, whether his fascination with polar exploration, his love of telemark skiing and fly fishing, or simply a conversation about the state of the world over a good cup of tea. I will miss him deeply, but his wisdom and his good humor will stay with me forever."
Dan Schrag, Director, HUCE; Sturgis Hooper Professor of Geology, Harvard University
"From the very beginning of his scientific career, Jim understood that many of the most fascinating problems in environmental science can neither be understood nor solved without drawing on insights from multiple disciplines. He brought that insight to bear in his own choices to work in oceanography, marine biology, and climate science, where interdisciplinarity is indispensable; and he brought it bear in his work at the intersection of science with public policy, where social sciences and humanities no less than a multitude of scientific disciplines are germane. Beyond the interdisciplinarity in his own work, Jim was a highly successful evangelist for that rubric, having long used his many platforms to communicate to his students, mentees, and the wider scientific community the importance of interdisciplinary approaches both within science and at its intersection with policy. Scientist, teacher, mentor, institution builder and leader, scientific statesman—Jim McCarthy excelled in every role. It is impossible to say which of these roles he relished the most, perhaps because he understood how they all intersect."
John P. Holdren,Teresa and John Heinz Professor, Kennedy School of Government; Department of Earth and Planetary Sciences; School of Engineering and Applied Science, Harvard University
"Jim was a global thinker—seamlessly integrating different disciplines to discover new insights about the ocean, climate change, and the planet. The depth and breadth of his thinking challenged and invigorated his students and colleagues alike. His joy in science was palpable; his passion for sharing scientific knowledge widely was inspiring. His lively engagement was a joy to behold, enriching everyone present. We will miss his gentle demeanor, penetrating mind, and passionate spirit."
Jane Lubchenco, Distinguished University Professor, Oregon State University; Recipient of the Harvard GSAS Centennial Medal, 2019; Former Under Secretary of Commerce for Oceans and Atmosphere and Administrator of the National Oceanic and Atmospheric Administration (NOAA; 2009-2013); Former inaugural U.S. Science Envoy for the Ocean (2014-2016)
"In many ways, Jim was the heart and soul of the Environmental Science and Public Policy (ESPP) concentration, which he helped found and then served as head tutor for many years. In thinking of his contributions to ESPP, what stands out for me is his kindness and steady hand. Jim always had time to listen to a student (or a colleague) and his gently delivered advice would be accompanied by that wonderful twinkle in his eye. His commitment to students and to making the world a better place inspired me, and I am sure many others, to do more and to care more. The ESPP students who now carry on his work are an important part of his legacy."
Missy Holbrook, Charles Bullard Professor of Forestry, Professor of Organismic and Evolutionary Biology; Head Tutor, Environmental Science and Public Policy, Harvard University
Listen to Professor McCarthy reflect on his career in a 5-part podcast series recorded in February and March of 2019: http://environment.harvard.edu/honoring-jim-mccarthy.
Watch the September 2019 symposium honoring Professor McCarthy: http://environment.harvard.edu/ocean-futures-jim-mccarthy.
With economies and populations surging, an industrial revolution is inevitable on the African continent. The question is, what’s going to power it? With renewable energy cheaper and more efficient than ever, countries in Africa have the unique opportunity to harness abundant renewable sources like wind, solar and geothermal to leapfrog the dependence on fossil fuels that has poisoned the air and environment in Europe, the U.S., India and China.
But will they?
New research from Harvard University and the University of Leicester finds that if Africa chooses a future powered by fossil fuels, nearly 50,000 people could die prematurely each year from fossil fuel emissions by 2030, mostly in South Africa, Nigeria and Malawi.
The research is published in Environmental Science and Technology.
“Our work shows the substantial health benefit of shifting to clean energy sources in Africa, which we hope can help incentivize the transition towards renewable energy over fossil fuels,” said Eloise Marais, a former graduate student of the Department of Earth and Planetary Sciences and postdoctoral fellow at the Harvard John A. Paulson School of Engineering and Applied Science (SEAS) and senior author of the paper.
Marais is now an Associate Professor at the University of Leicester.
The researchers focused on air pollution from power plants and transportation, as many African countries are currently working to increase fossil-fuel power plants and vehicle infrastructure. South Africa, for example, is commissioning the largest dry-cooled coal-fired power plant in the world. Namibia, Ghana and Mozambique are all turning to offshore power plants — known as powerships — that run on the dirty residue from crude oil refining.
The researchers calculated emissions from all the current power plants on the continent as well as the projected emissions of all power plants proposed as of November 2017. They calculated vehicle emissions based on increases in population that they showed is strongly tied to vehicle usage. They then plugged all the data into the GEOS-Chem global transport model, the open source pollution model developed and housed at Harvard.
The researchers found that continent-wide,13,000 people would die prematurely each year from exposure to vehicle emissions and 39,000 people would die from exposure to pollutants from power plants. Most of those deaths are in southern Africa, where most of the new power plants are being planned.
Interestingly, some countries without any planned power plants also show high rates of mortality. Pollution from power plants in South Africa and Botswana, for example, travels as far as northern Angola because of winds and air circulation.
“This research shows that if we can cut emissions in southern Africa, and South Africa specifically, it can have a far-reaching impact on health,” said Marais.
"Africa has the opportunity to avoid the mistakes that much of the rest of the world has made in electricity generation and transportation,” said Joel Schwartz, Professor of Environmental Epidemiology at the Harvard T.H. Chan School of Public Health and co-author of the study. “The technology to avoid these mistakes already exists. Making these choices for clean energy will greatly benefit the health of Africans."
“Our work suggests that the countries of Africa can show the way toward cleaner energy, with benefits for both the earth’s climate and the air that millions breathe,” said Loretta Mickley, Senior Research Fellow at SEAS and co-author of the study.
This research was co-authored by Rachel Silvern, Alina Vodonos, Eleonore Dupin, and Alfred Bockarie. It was supported by the Wallace Global Fund and the UK National Environmental Research Council.
By Colleen Walsh, Harvard Staff Writer
Simply put, said Patrick Behrer, the world is getting hotter “and that heat imposes large costs on people.” In particular, those who work outdoors or in factories lacking air conditioning or ventilation are most at risk for the ill effects of on-the-job heat exposure such as sun stroke, impaired cognitive function, and possibly even death.
Behrer ’09, an environmental and developmental economist and Harvard Ph.D. candidate in the Graduate School of Arts and Sciences, emphasizes the looming scale of the crisis with a little math. Given the nature of climate change, he said, the shifts in the number of very hot days will be greater than those in the mean temperature.
For example, a uniform, global temperature increase of 2 degrees Fahrenheit would shift Boston’s mean temperature from roughly 52 to 54 degrees Fahrenheit. On its face, not a catastrophic jump.
“But what that does mean in a place like Boston where we currently have periodic hot days, is that you are moving the tails of the distribution and dramatically increasing the number of extremely hot days,” said Behrer. “From the mid ’80s to the early 2000s Boston averaged somewhere between five and eight days above 90 degrees. Taking some of the median projections up to 2050, Boston’s projected to see somewhere between 30 and 50 days above 90 degrees a year, even though the mean temperature change is only going to be a few degrees.”
And those extra-warm days would take a dramatic toll on the nation’s workforce. In the past, the climate-change narrative has tended to highlight negative environmental outcomes: the loss of crops, more frequent and more violent storms, increased flooding, and sea level rise. But experts have long been aware of the negative health effects of exposure to heat. Studies have shown a substantial increase in deaths as the temperature exceeds 90 degrees, said Behrer, who hopes his work can help shine a light on how rising temperatures are affecting workers in vulnerable jobs.
Source: NOAA (2019); World Climate Research Programme via Patrick Behrer and Jisung Park (2050 projections)
In response to rising worries over climate change, Harvard pledged in 2008 to reduce its greenhouse gas emissions 30 percent by 2016, a goal it achieved. The University is now working to become fossil-fuel-neutral by 2026 and free by 2050. It is also funding numerous research efforts in the field.
With the support of a grant from Harvard’s Climate Change Solutions Fund, Behrer and colleague Jisung Park, an assistant professor at the University of California, Los Angeles, who earned his Ph.D. at Harvard, are tracking the health effects of working in a hot environment and the ripple effects on the economy, including reduced productivity and pay.
The study builds on Park’s earlier Harvard research that examined heat stress on student performance. Using new data from both the U.S. government and California, Behrer and Park will examine the impacts of heat on workplace safety across the entire country, as well as on a more granular, “finely resolved” state level.
“Relative to the other damages of climate change, the impact of any given hot day is small, both in absolute and relative terms; some of our other work suggests that just one additional hot day removes a fraction of a percent of your annual take-home pay,” said Behrer, referring to lost time on the job that is heat-related. “When you start talking about going from eight extremely hot days to 50 extremely hot days, then that that adds up very quickly. It also adds up very quickly when you’re taking a fraction of a percent of pay away from large parts of the United States.”
Behrer thinks his research could help experts as they continue to revise the process used to calculate the social cost of carbon — the measure in dollars of the long-term damage done by a ton of carbon dioxide emissions in a given year. Currently the figure is roughly $50 per ton. Adding heat, especially its mortality impacts, into that calculation “could increase that number by 25 to 50 percent, or possibly more,” said Behrer.
He also hopes his work will inform policy and contribute to the conversation around a national standard for workplace heat exposure. The National Institute for Occupational Safety and Health has published criteria for a recommended standard for on-the-job heat stress, which includes recommendations for employers about how to prevent heat-related illnesses. Three states, California, Washington and Minnesota, have adopted their own standards for workplace heat exposure, but a federal requirement doesn’t yet exist.
Behrer said such a national code could be costly to firms that already comply with workplace heat recommendations, and that regional humidity levels could mean a state-by-state regulatory approach is more efficient. “We’re still uncertain a national standard is the best approach,” said Behrer. “That’s one of the questions we are aiming to answer with our research.”
Shining a light on the nation’s rising inequality is another important dimension to Behrer’s work. Lower-wage workers such as landscape, construction, and agricultural laborers are set to suffer disproportionately as the planet warms, he said, and it’s not only those required to spend eight hours a day outside who are at greater risk.
“Manufacturing is also one of the other big industries in which large parts of the working population are exposed to heat, because a lot of a lot of large-scale manufacturing installations are just simply too large to be air conditioned,” said Behrer. “So you’re inside in a very real sense, but the building is not climate-controlled in any way. It can actually be hotter inside the building than outside of the building. And so there’s a question about whether the standards should be targeted specifically at those working outside or just written more broadly.”
Behrer, who loves the outdoors, said he always knew his professional life would be in “the environmental space.” He had intended to apply to law school after college, but early in his first year he found himself returning to a conversation he’d had with his father, a general contractor in Pennsylvania who had watched roofers adjust their start times to 3 a.m. to avoid the brutal afternoon sun. “We talked about how it seemed like the front in the environmental movement was shifting from the legal space to the economic space.”
So he concentrated in economics, a field where he felt he could make the biggest impact. He sees his current research as vital in the effort to help mitigate the harmful effects of climate change.
“I wouldn’t be working on this,” Behrer said, “if I didn’t think it was a huge, huge problem.”
By Jill Radsken, Harvard Staff Writer
Just back from sabbatical Naomi Oreskes has published “Why Trust Science?,” a timely book that examines the value of the scientific process of proof and verifiable facts in an era when both are under fire. Though the geologist-turned-history-of-science professor’s field is climate, she turned a critical eye to research ranging from sunscreen to birth control. Oreskes, who has co-authored or edited seven books and has a forthcoming one on Cold War oceanography, talked to the Gazette about the five pillars necessary for science to be considered trustworthy, the evidentiary value of self-reporting, and her Red State Pledge.
GAZETTE: “Why Trust Science?” came out of a Tanner Lecture you gave at Princeton three years ago. Why did you feel it needed a broader audience?
ORESKES: I’ve given more than 100 lectures on climate change over the years. In the past, a lot of my work was about the history of climate science and telling the story of how and why scientists even got interested in this question about whether greenhouse gases would change the Earth’s climate. Part of the point of telling the story this way was to show our concern wasn’t some fad or the latest environmental anxiety. It was something scientists had been tracking for a long time. Many of these scientists weren’t even environmentalists; they were just scientists interested in how the world works, but who realized there was this potential problem. This was increasingly in a context of climate change skepticism, a public that was at best confused about the issue and sometimes in denial.
As a speaker and teacher I always try to take questions seriously, but because of the topic, sometimes people are belligerent, sometimes hostile. I can almost tell when a belligerent question is coming. (And I have to say, and this is my empirical experience: They’re always men, almost always over 50-ish, and they stand up using belligerent body language.) So this man stands up in a very aggressive way and tone of voice and says: “Well, that’s all well and good, but why should we believe you or trust the science anyway?” I went home that night and thought: “Yeah, that’s a fair question.” There’s an implicit argument that science is trustworthy, but if a person doesn’t assume science is trustworthy, then my story breaks down. Maybe five years ago I started to begin forming a mental argument. Then I was asked to give a TED talk. It was very successful for a serious intellectual topic. People liked it, but I felt that 18 minutes was, frankly, not enough for a topic of this gravity. Also, the title I had been given, by the TED folks, was “Why Trust Scientists?” Later I realized that title was wrong. It wasn’t about trusting scientists; it was about trusting science as a process, an enterprise, or an activity. So when I was approached about the Tanners, I knew what I wanted to say.
GAZETTE: Can you talk about the way you have thought about your career as an academic that has taken you far from TED Talks and Tanner Lectures?
ORESKES: There’s a lot that’s good and important about sustaining the intellectual enterprise and not having it be driven by short-term considerations, but there’s also a way that academic life can be very ingrown, and inwardly focused, and preoccupied with speaking to “the right people.” What that means often at a place like Harvard is that if people get invited to talk at Princeton, we say yes. But sometimes when you’re working on an issue like climate change, Princeton is not where you’re needed. You’re needed at South Dakota State University. Often people there have interesting things to say because they live in South Dakota and see the world from a different perspective. It makes you a better scholar and a better human being when you engage with people who are viewing the world from a different perspective. So I embrace the opportunity to go to places that other people might not embrace, and I have what I call my Red State Pledge, which is if I get invited to a Red State, I do everything in my power to accept that invitation.
When “Merchants of Doubt” came out, we had a wonderful publisher, but when it came time to do a book tour, they were only planning to send us to big cities on the coasts where people buy and read a lot of books. That’s understandable from a business-model standpoint, and if your goal is to simply sell books and get a review in The New York Times, that makes sense. But if your goal is to reach people with a message you think they need to hear, it’s incomplete. I was lucky when “Merchants of Doubt” came out that people wanted to help get the word out. I got a phone call — out of the blue — from a reporter in Manhattan, Kan. He said, “If I can arrange logistics on the ground, would you come to Kansas?” And I said, “Yes, absolutely.” He arranged a three-city book tour for me of Lawrence, Manhattan, and Hays. Hays is serious wheat country. After giving the lecture in Hays, I’m signing books and a woman came up to me and said, “God bless you for coming to Hays.” That moment summarized everything I needed to know about the choices I was making. I’m not going to win a book prize for going to Hays, Kan., but I won a different kind of prize.
GAZETTE: In the book you lay out five pillars for how to think about science that can be trusted. How did you come to them?
ORESKES: I’m an empiricist, not a theorist: All of my work is based on upon studying the world as it is, in its historical complexity. When I was a scientist, I was the same way. The transition from science to history was easy for me because it involved almost no methodological/intellectual adjustment. I had been an empirical geologist, and in geology the world is really complicated. Theory plays a role in the sense that theory from physics or chemistry or biology constrains the possibilities for what can be happening on the Earth, but you cannot deduce geological processes from the laws of physics or chemistry. So there’s a limit to where theory gets you in geology. Ultimately to understand the Earth you have to go out and look at it and study it. That’s my approach to history as well. I’m very empirical: I don’t assume up front that I know what the structure of something is before I study it. Over the course of 100–150 years, a lot of really smart people thought really hard about what makes science science. They kept trying to come up with the one thing. Essentially my argument is: It isn’t one thing. Letting go of the notion of the one thing is hard in a European-derived culture. Unlike politics or human relationships, science is a success story, so we need an account that both embraces the reality of how complex it appears to be when you look at it, but also can explain how it has been efficacious. I didn’t start out thinking there would be five key elements, but that’s where I got to: consensus, diversity, method, evidence, and values.
GAZETTE: You take a writer to task for calling self-reporting “iffy” science. Can you elaborate?
ORESKES: The dismissal of self-reporting is a big issue in medicine. It’s one of the reasons why women’s complaints have not been taken seriously. But they should be. If a patient goes to a doctor and says, “I’m depressed and I’ve been depressed since I’ve gone on this medication,” that’s evidence. It might not be an RCT [randomized clinical trial], but it’s still evidence. The writer in question recapitulated that error, saying that previous studies were right to dismiss self-reports as “iffy.” I think that is wrong. This is where it gets personal for me because I got depressed being on the pill. I’m up front with this. I was very lucky that my doctor did not dismiss my self-report. I went off the pill and recovered almost immediately. But imagine the horrible path one could go down being put on antidepressants when the cause of your depression is hormonal contraception. Since I wrote “Why Trust Science?,” I read Hilary Mantel’s memoir “Giving Up the Ghost.” She spent 20 years of her life in pain, being told that her pain was all psychosomatic, being put on antidepressant drugs that made her fat and created all kinds of other side effects. It turns out she had systemic endometriosis, which can spread beyond the reproductive organs. She spent an incredible amount of her time suffering physical pain that her doctors did not take seriously and being mistreated. It’s pretty scary. It makes one wonder how many people are out there suffering because of misdiagnoses, because doctors didn’t take seriously their self-reports? Because self-reports aren’t “hard data.” One thing history tells us is that people sometimes dismiss evidence because it doesn’t fit some notion they have of what should constitute good evidence, and often those judgments are incorrect.
GAZETTE: In a chapter about science gone awry, you cite provocative research about dental floss and about sunscreen that lands loudly in the press. So what is the role of media in shaping what science is trustworthy?
ORESKES: One thing that happens in the media is the desire to be different, to report something surprising, unexpected. The article in Outside magazine, which claimed that sunscreen is bad for us, had a gotcha, contrarian tone, with a bit of schadenfreude thrown in. It also followed the cliché of the renegade scientist who turned out to be right. Well, sometimes renegades are right, but most of the time they are just renegades.
The editors at Outside believe that being outdoors is good for you, and so do I. Being outdoors is good for your overall health, but that doesn’t mean that it’s good to get a sunburn, especially if you are a white person living in a very sunny place. If you think about people who live naturally in those climates, typically they are dark-skinned or they have adaptations to protect themselves. In a way, sunscreen is our adaptation. And there is a large body of data to say that using sunscreen is beneficial. But the magazine ran with a claim based on one very small study, and a second larger study that has not yet been published. That was very irresponsible journalism.
Schadenfreude was definitely in play with the dental floss story, which claimed there was very little “solid” evidence to support the conclusion that flossing is good for your health. The journalist who wrote it was obviously very pleased with himself, as if he had unmasked a great dental floss conspiracy.
If you know anything about science, you can understand why we don’t have any good studies about flossing. You can’t do a double-blind clinical trial of flossing. You can’t even do a single-blind trial. Most of the time you can’t even get people to floss. This is the point: Nobody likes flossing. So there’s a way in which it was very satisfying to conclude that flossing is no good. The fact is dentists aren’t idiots; they look at teeth every day and they can see that people who floss have healthier gums than people who don’t. That’s evidence, so why would we dismiss it?
GAZETTE: How can science be value free?
ORESKES: It isn’t! All people have values, and we always will have values. We do the things we do because we care about things. And that’s a good thing. And if you had scientists with no values, that would be truly scary. That’s the Frankenstein myth, Mary Shelley’s argument that if you let science run amok without thinking of the moral consequence of the action you end up with a monster. What people often forget is that Frankenstein is the doctor, the scientist. The monster he creates is called the Monster, but the point of the book is: The science is the monster. We don’t do anywhere near enough to talk about this in our classrooms, or in our research. As a serious question in the practice of science, what are the values driving the science, and are they good or bad? I think that is a conversation we need to have.
By Alvin Powell, Harvard Staff Writer
The Intergovernmental Panel on Climate Change (IPCC) released a special report last week warning of the mounting effects of global warming on the seas, increasing temperatures and acidification, and on the world’s melting ice. It noted the potential dangers from sea level rise, water shortages in glacier-fed rivers, declining and shifting fish stocks, and increased frequency and severity of storms, among many other hazards. The release came during a week marked by climate-related activities, from youth protests around the world to a United Nations summit meeting of global leaders to consider the issue.
The Gazette spoke with John Holdren, the Teresa and John Heinz Professor of Environmental Policy at the Harvard Kennedy School, of environmental science and policy in the Department of Earth and Planetary Sciences, and affiliated professor in the John A. Paulson School of Engineering and Applied Science. Holdren was director of the White House Office of Science and Technology Policy during the Obama administration and now co-leads the Arctic Initiative at HKS’ Belfer Center for Science and International Affairs.
Surprisingly, while the situation seems urgent, Holdren suggested there may be something positive lurking under the gloom.
GAZETTE: These IPCC reports on climate seem to be getting more and more dire. Is there any good news in this latest report, the “Special Report on the Ocean and Cryosphere”?
HOLDREN: I don’t think there’s any good news in the report because it’s focused only on the science, and it’s been true for decades now that virtually all of the new news from climate science has been bad news. The current good news is on the public awareness side. It’s that the fraction of the American public and of publics around the world who understand that climate change is real, caused by humans, already doing significant damage, and that we need to act, has been going up. I actually think we could be close to a political tipping point, because of the combination of expanded grassroots conviction that more needs to be done and these authoritative reports underscoring how pervasive the impacts of climate change already are, even though we’re just at about 1 degree Celsius above the preindustrial temperature.
GAZETTE: It seemed like for many years the job was to convince people about the science of climate change. Are we at a point where that job has been mostly done, positions are more or less baked in on either side, and the question now is going to be decided at the ballot box?
HOLDREN: The polls now show that between 70 and 80 percent of the U.S. electorate is convinced about the realities of climate change. So, the challenge is not to persuade the last 20 or 30 percent. We don’t need them. Seventy or 80 percent support is more than we’ve had for almost any change in our political system over the life of the republic. What we need to do is to persuade those who are already convinced about the science to increase their sense of urgency, to decide that they need to work for and vote for candidates who understand this issue and are prepared to take serious action. Our problem now is that, although a high percentage of the American electorate understands that climate change is real and caused by humans, if you ask the same people, “What keeps you awake at night?” they’re worried about their jobs, getting their kids through college, their retirement, the health system, drugs, terrorism. Climate change tends to come in number eight or nine. But that’s progress. When I started talking to President [Barack] Obama about these matters in 2007, the percentage who believed in the reality of human-caused climate change was between 60 and 65 percent. And the priority ranking was 18 or 19.
GAZETTE: Did the climate protests last week — the fact that they were global in scope and youth-driven — move the needle a little bit?
HOLDREN: Absolutely. In my view, most of the major sociopolitical changes that have occurred in this country and elsewhere — Civil Rights, improving the status of women, and many others — have resulted from a combination of what you might call bottom-up and top-down influences. Consider how the Vietnam War ended. It ended because of the interaction of defections at the top — people like Daniel Ellsberg [who leaked the Pentagon Papers in 1971] on the inside, saying, “Wait a minute, the emperor has no clothes” — and the bottom-up withdrawal of public support that occurred after virtually every American had either a family member or a friend who had been killed or injured in Vietnam, and nobody could really explain why. I think we’re seeing that with climate change: from the top, with reports like those of the IPCC and the U.S. National Climate Assessment, which comes out roughly every four years, on the impacts of climate change on the United States. The last one was released on the day after Thanksgiving last year — Black Friday — and in spite of that it got big coverage in the mainstream media outlets. That in itself was a sign of positive change in concern about this issue.
GAZETTE: Is the “bottom-up” in this case driven by Texas, the Caribbean, the Carolinas getting hit again and again? Is that convincing people?
HOLDREN: I think there’s no question about it. People are experiencing more, longer, stronger heat waves; more and bigger torrential downpours producing more flooding; hotter wildfires burning larger areas and destroying more property; longer allergy seasons; worse pest outbreaks; and more.
If you look at the number of countries in which the highest temperatures ever recorded have occurred in just the last three or four years, it’s absolutely extraordinary. In almost every ocean basin in which hurricanes and typhoons occur, the largest and strongest ones ever recorded have occurred since 2012. One of the things the new IPCC ocean and cryosphere report emphasized very powerfully is that, in many parts of the world, previously once-per-century extreme sea level events are now going to occur every year by 2050. We’re going to have 100-year storms every year. This will happen in spite of a relatively modest change in the globally and annually average surface temperature of the Earth.
GAZETTE: There are a lot of different projections in this report. Was there anything that surprised you?
HOLDREN: The climate scientists who have looked most broadly at the impacts of climate change are not surprised by this report. What you need to understand about the IPCC is that it is the nature of the beast that they only establish the floor on what we know, they are almost never on the cutting edge.
“I don’t think there’s any good news in the report because it’s focused only on the science, and it’s been true for decades now that virtually all of the new news from climate science has been bad news.”
There are scores of authors, and you’re never going to get all those authors to agree on what the top two or three understand in their own field. For example, they said in this new report that, by 2100, sea level might go up by a meter. That’s an increase on what the IPCC said before, but NOAA said in 2012 that the increase could be as much as two meters by 2100. This is typical.
The IPCC approach makes their results very respectable, because they got all these people to agree, but it certainly isn’t describing the worst that could happen. This report says some very sensible things about the influence of rapid climate change in the Arctic. One of these points is that, as the sea ice and the snow cover shrink, we’ll see impacts on the circulation patterns of the atmosphere over much of the Northern Hemisphere. The new report is more cautious than I would be on that particular issue. While the new IPCC report says, “It’s likely that there will be influences in this domain, but our confidence is low to medium,” in my view, I think expert confidence is already high. I think we’re already seeing effects and remaining disagreements among experts in this space are about how exactly it works, about the relative importance of different mechanisms that contribute to making the polar jet weaker and wavier. The waviness means that, in downward lobes, more cold, Arctic air penetrates in the midlatitudes, and, in the upward lobes, more warm midlatitude air penetrates into the far north.
GAZETTE: Is that the polar vortex we’ve seen?
HOLDREN: Yes, it’s what the media have called the polar vortex. Technically, the polar vortex has always been there. What’s changing is its speed and shape. I think the evidence for that [shifting circulation pattern] is stronger than the current IPCC report reflects. If you look at the history of IPCC reports going back to their inception in 1990, each one has reported increasing confidence, higher certainty, and bigger effects. The reality is that many of the effects of climate change are now manifesting more rapidly than was projected even 10 or 15 years ago.
GAZETTE: One thing mentioned during the news conference after the report was released was tipping points where a small change creates a cascade of changes from which there may not be any going back. Are there any of those that you see as particularly worrisome or likely?
HOLDREN: I think the most worrisome one is the possibility that we will get to the point where the thawing permafrost is emitting enormous quantities of both carbon dioxide and methane. We know the permafrost contains 2-and-a-half times as much carbon as is now in the atmosphere. It’s organic carbon that has been frozen undecomposed for millennia. As the permafrost thaws under the rapidly warming Arctic climate, that carbon becomes susceptible to bacterial decomposition. If the circumstances are anaerobic, the decomposition produces methane; if they’re aerobic — if oxygen is present — it produces CO2. Methane is worse in the short term. On a 100-year time scale, the methane is 30 times as potent a heat-trapping gas as CO2 per molecule. We don’t know yet at what point the permafrost will have thawed to a level at which these emissions become a really big deal. There’s already a lot of evidence that the permafrost is disgorging more CO2 and methane than it did before the human-caused warming raised the temperature. But, again, I think the evidence there is a little stronger than the IPCC report reflects.
In second place, but not by much, is the drying out of the tropical forests. If you look at what’s happening already in the Amazon and, to a lesser extent, in the tropics in Indonesia and central Africa, you see very strong drying tendencies already very evident.
GAZETTE: Is that causing the fires we’re seeing in the Amazon?
HOLDREN: Fire has been a longstanding phenomenon in the Amazon, but fires now are bigger, hotter, and get out of control more easily. You see this in Indonesia as well. Roughly a million people in that country are suffering acute air pollution because smoke from the fires is so widespread. We’ve seen that phenomenon in the United States, too. The wildfires in the Northwest — in Northern California, Oregon, and Washington State — have transmitted dangerous levels of fine particulates all the way to New England. These bigger, hotter fires generate a lot of smoke and transmit it farther.
GAZETTE: Climate change is characterized by these big problems and long-term effects. Are there things in the short term that can be reversed?
HOLDREN: The difficulty in a problem like climate change is the time lag. By the time there are dead bodies in the street, you’re already way down the road. At any given time, we’re not experiencing everything that we’re already committed to. That causes policymakers and publics to underestimate how bad it is. If we could somehow freeze the atmospheric concentrations of heat-trapping gases and reflecting particles where they are today, the temperature would still rise to close to 1.5 degrees C above preindustrial times. If we actually want to stay below 1.5 — and the IPCC report from last fall argued that doing so would bring big benefits compared to going to 2 degrees or more — we really have to start reducing our emissions very rapidly. We’ll eventually have to be actually pulling more carbon dioxide out of the atmosphere than we’re adding in order to meet that extremely challenging goal.
The good news is it’s still up to us how bad the impacts of climate change get. It’s going to get worse, but it’ll get a lot less bad if we take action than if we don’t. If we do a lot, we can end up with a temperature increase of 2 or 2.5 degrees. If there are major breakthroughs, maybe we can get back to 1.5. And that will be a vastly better world than business as usual, where, by the turn of this century, you get to 4 or 4.5 degrees C.
Image: Stephanie Mitchell, Harvard Staff Photographer