From The Yale School of the Environment: “How Circular Utilization of Urban Tree Waste Can Help Mitigate Climate Change”

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From The Yale School of the Environment

at

Yale University

8.23.22
Josh Anusewicz
Assistant Editor
joshua.anusewicz@yale.edu
+1 203-436-8994

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YSE Study Finds Circular Utilization of Urban Tree Waste Can Help Mitigate Climate Change. Credit: The Yale School of the Environment.

A multi-scale lifecycle assessment conducted by Prof. Yuan Yao and researchers from the Center for Industrial Ecology explains how eco-friendly uses for urban tree waste could substantially reduce greenhouse gas emissions in U.S. cities.

Cities are defined, by most, by their built environment: towering buildings, miles of roads and sidewalks, modes of transportation, and public utilities. But with the threats of climate change looming, researchers are looking for ways to turn vast swaths of natural areas in urban environments into tools to help offset the significant greenhouse gas emissions that cities produce.

In a recent study published in the journal One Earth [below], researchers from the Yale Center for Industrial Ecology conducted a multi-scale lifecycle assessment that explored methods for utilizing urban tree waste. Wide-scale adoption of more eco-friendly uses of urban tree waste could significantly reduce global warming potential in the United States, according to the researchers’ findings.

“Cities have lots of trees and they will not live forever,” says co-author Yuan Yao, assistant professor of industrial ecology and sustainable systems. “You also have leaves and other tree waste. We wanted to investigate different ways we could use this waste, the potential pathways and benefits, to create something of value.”

According to Kai Lan, a postdoctoral researcher in Yao’s lab and the lead author of the study, there are roughly 50 million hectares of urban forest in the United States. As a result, more than 45 million dry tons of urban tree waste are generated every year in the United States — waste that usually ends up in landfills to be disposed of, contributing greatly to greenhouse gas emissions.

The study outlines several different methods for creating value from urban tree waste, including turning tree trunks into wood chips or lumber for wood products, composting leaves, and turning tree residue into biochar, a carbon-rich material made from biomass. Yao specifically highlighted the numerous applications for biochar, which include agriculture, energy, wastewater treatment, and carbon storage.

The researchers caution that the environmental benefits of new uses for urban tree waste will vary across states and cities. Bingquan Zhang, a postdoctoral researcher in Yao’s lab and an author of the study, says that several major U.S. cities have developed urban tree management strategies and that those efforts should be expanded.

“I hope this paper can provide some quantitative evidence that programs like these are working in climate mitigation efforts,” says Yao, who added that she also hopes this study lays the foundation for global collaboration on the topic.

“This all aligns with the circular economy concept — turning waste into something of value,” says Lan. “But it’s not just traditional waste, like plastic or paper. Tree waste is very important, too.”

Science paper:
One Earth

See the full article here .

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The Yale School of the Environment

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Yale School of the Environment Vision and Mission

We are leading the world toward a sustainable future with cutting-edge research, teaching, and public engagement on society’s evolving and urgent environmental challenges.

Core Values

Our Mission and Vision are grounded in seven fundamental values:

Excellence: We promote and engage in path-breaking science, policy, and business models that build on a fundamental commitment to analytic rigor, data, intellectual integrity, and excellence.
Leadership: We attract outstanding students nationally and internationally and offer a pioneering curriculum that defines the knowledge and skills needed to be a 21st century environmental leader in a range of professions.
Sustainability: We generate knowledge that will advance thinking and understanding across the various dimensions of sustainability.
Community: We offer a community that finds strength in its collegiality, diversity, independence, commitment to excellence, and lifelong learning.
Diversity: We celebrate our differences and identify pathways to a sustainable future that respects diverse values including equity, liberty, and civil discourse.
Collaboration: We foster collaborative learning, professional skill development, and problem-solving — and we strengthen our scholarship, teaching, policy work, and outreach through partnerships across the university and beyond.
Responsibility: We encourage environmental stewardship and responsible behavior on campus and beyond.

Guiding Principles

In pursuit of our Mission and Vision, we:

Build on more than a century of work bringing science-based strategies, ethical considerations, and conservation practices to natural resource management.
Approach problems on a systems basis and from interdisciplinary perspectives.
Integrate theory and practice, providing innovative solutions to society’s most pressing environmental problems.
Address environmental challenges at multiple scales and settings — from local to global, urban to rural, managed to wild.
Draw on the depth of resources at Yale University and our network of alumni who extend across the world.
Create opportunities for research, policy application, and professional development through our unique centers and programs.
Provide a diverse forum to convene conversations on difficult issues that are critical to progress on sustainability.
Bring special focus on the most significant threats to a sustainable future including climate change, the corresponding need for clean energy, and the increasing stresses on our natural resources.

Statement of Environmental Policy

As faculty, staff, and students of the Yale School of the Environment, we affirm our commitment to responsible stewardship of the environment of our School, our University, the city of New Haven, and the other sites of our teaching, research, professional, and social activities.

In the course of these activities, we shall strive to:

reduce our use of natural resources;
support the sustainable production of the resources we must use by purchasing renewable, reusable, recyclable, and recycled materials;
minimize our use of toxic substances and ensure that unavoidable use is in full compliance with federal, state, and local environmental regulations;
reduce the amount of waste we generate and promote strategies to reuse and recycle those wastes that cannot be avoided;
restore the environment where possible.

Each member of the School community is encouraged to set an example for others by serving as an active steward of our environment.

Yale University is a private Ivy League research university in New Haven, Connecticut. Founded in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and one of the nine Colonial Colleges chartered before the American Revolution. The Collegiate School was renamed Yale College in 1718 to honor the school’s largest private benefactor for the first century of its existence, Elihu Yale. Yale University is consistently ranked as one of the top universities and is considered one of the most prestigious in the nation.

Chartered by Connecticut Colony, the Collegiate School was established in 1701 by clergy to educate Congregational ministers before moving to New Haven in 1716. Originally restricted to theology and sacred languages, the curriculum began to incorporate humanities and sciences by the time of the American Revolution. In the 19th century, the college expanded into graduate and professional instruction, awarding the first PhD in the United States in 1861 and organizing as a university in 1887. Yale’s faculty and student populations grew after 1890 with rapid expansion of the physical campus and scientific research.

Yale is organized into fourteen constituent schools: the original undergraduate college, the Yale Graduate School of Arts and Sciences and twelve professional schools. While the university is governed by the Yale Corporation, each school’s faculty oversees its curriculum and degree programs. In addition to a central campus in downtown New Haven, the university owns athletic facilities in western New Haven, a campus in West Haven, Connecticut, and forests and nature preserves throughout New England. As of June 2020, the university’s endowment was valued at $31.1 billion, the second largest of any educational institution. The Yale University Library, serving all constituent schools, holds more than 15 million volumes and is the third-largest academic library in the United States. Students compete in intercollegiate sports as the Yale Bulldogs in the NCAA Division I – Ivy League.

As of October 2020, 65 Nobel laureates, five Fields Medalists, four Abel Prize laureates, and three Turing award winners have been affiliated with Yale University. In addition, Yale has graduated many notable alumni, including five U.S. Presidents, 19 U.S. Supreme Court Justices, 31 living billionaires, and many heads of state. Hundreds of members of Congress and many U.S. diplomats, 78 MacArthur Fellows, 252 Rhodes Scholars, 123 Marshall Scholars, and nine Mitchell Scholars have been affiliated with the university.

Research

Yale is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”. According to the National Science Foundation , Yale spent $990 million on research and development in 2018, ranking it 15th in the nation.

Yale’s faculty include 61 members of the National Academy of Sciences , 7 members of the National Academy of Engineering and 49 members of the American Academy of Arts and Sciences . The college is, after normalization for institution size, the tenth-largest baccalaureate source of doctoral degree recipients in the United States, and the largest such source within the Ivy League.

Yale’s English and Comparative Literature departments were part of the New Criticism movement. Of the New Critics, Robert Penn Warren, W.K. Wimsatt, and Cleanth Brooks were all Yale faculty. Later, the Yale Comparative literature department became a center of American deconstruction. Jacques Derrida, the father of deconstruction, taught at the Department of Comparative Literature from the late seventies to mid-1980s. Several other Yale faculty members were also associated with deconstruction, forming the so-called “Yale School”. These included Paul de Man who taught in the Departments of Comparative Literature and French, J. Hillis Miller, Geoffrey Hartman (both taught in the Departments of English and Comparative Literature), and Harold Bloom (English), whose theoretical position was always somewhat specific, and who ultimately took a very different path from the rest of this group. Yale’s history department has also originated important intellectual trends. Historians C. Vann Woodward and David Brion Davis are credited with beginning in the 1960s and 1970s an important stream of southern historians; likewise, David Montgomery, a labor historian, advised many of the current generation of labor historians in the country. Yale’s Music School and Department fostered the growth of Music Theory in the latter half of the 20th century. The Journal of Music Theory was founded there in 1957; Allen Forte and David Lewin were influential teachers and scholars.

In addition to eminent faculty members, Yale research relies heavily on the presence of roughly 1200 Postdocs from various national and international origin working in the multiple laboratories in the sciences, social sciences, humanities, and professional schools of the university. The university progressively recognized this working force with the recent creation of the Office for Postdoctoral Affairs and the Yale Postdoctoral Association.

Notable alumni

Over its history, Yale has produced many distinguished alumni in a variety of fields, ranging from the public to private sector. According to 2020 data, around 71% of undergraduates join the workforce, while the next largest majority of 16.6% go on to attend graduate or professional schools. Yale graduates have been recipients of 252 Rhodes Scholarships, 123 Marshall Scholarships, 67 Truman Scholarships, 21 Churchill Scholarships, and 9 Mitchell Scholarships. The university is also the second largest producer of Fulbright Scholars, with a total of 1,199 in its history and has produced 89 MacArthur Fellows. The U.S. Department of State Bureau of Educational and Cultural Affairs ranked Yale fifth among research institutions producing the most 2020–2021 Fulbright Scholars. Additionally, 31 living billionaires are Yale alumni.

At Yale, one of the most popular undergraduate majors among Juniors and Seniors is political science, with many students going on to serve careers in government and politics. Former presidents who attended Yale for undergrad include William Howard Taft, George H. W. Bush, and George W. Bush while former presidents Gerald Ford and Bill Clinton attended Yale Law School. Former vice-president and influential antebellum era politician John C. Calhoun also graduated from Yale. Former world leaders include Italian prime minister Mario Monti, Turkish prime minister Tansu Çiller, Mexican president Ernesto Zedillo, German president Karl Carstens, Philippine president José Paciano Laurel, Latvian president Valdis Zatlers, Taiwanese premier Jiang Yi-huah, and Malawian president Peter Mutharika, among others. Prominent royals who graduated are Crown Princess Victoria of Sweden, and Olympia Bonaparte, Princess Napoléon.

Yale alumni have had considerable presence in U.S. government in all three branches. On the U.S. Supreme Court, 19 justices have been Yale alumni, including current Associate Justices Sonia Sotomayor, Samuel Alito, Clarence Thomas, and Brett Kavanaugh. Numerous Yale alumni have been U.S. Senators, including current Senators Michael Bennet, Richard Blumenthal, Cory Booker, Sherrod Brown, Chris Coons, Amy Klobuchar, Ben Sasse, and Sheldon Whitehouse. Current and former cabinet members include Secretaries of State John Kerry, Hillary Clinton, Cyrus Vance, and Dean Acheson; U.S. Secretaries of the Treasury Oliver Wolcott, Robert Rubin, Nicholas F. Brady, Steven Mnuchin, and Janet Yellen; U.S. Attorneys General Nicholas Katzenbach, John Ashcroft, and Edward H. Levi; and many others. Peace Corps founder and American diplomat Sargent Shriver and public official and urban planner Robert Moses are Yale alumni.

Yale has produced numerous award-winning authors and influential writers, like Nobel Prize in Literature laureate Sinclair Lewis and Pulitzer Prize winners Stephen Vincent Benét, Thornton Wilder, Doug Wright, and David McCullough. Academy Award winning actors, actresses, and directors include Jodie Foster, Paul Newman, Meryl Streep, Elia Kazan, George Roy Hill, Lupita Nyong’o, Oliver Stone, and Frances McDormand. Alumni from Yale have also made notable contributions to both music and the arts. Leading American composer from the 20th century Charles Ives, Broadway composer Cole Porter, Grammy award winner David Lang, and award-winning jazz pianist and composer Vijay Iyer all hail from Yale. Hugo Boss Prize winner Matthew Barney, famed American sculptor Richard Serra, President Barack Obama presidential portrait painter Kehinde Wiley, MacArthur Fellow and contemporary artist Sarah Sze, Pulitzer Prize winning cartoonist Garry Trudeau, and National Medal of Arts photorealist painter Chuck Close all graduated from Yale. Additional alumni include architect and Presidential Medal of Freedom winner Maya Lin, Pritzker Prize winner Norman Foster, and Gateway Arch designer Eero Saarinen. Journalists and pundits include Dick Cavett, Chris Cuomo, Anderson Cooper, William F. Buckley, Jr., and Fareed Zakaria.

In business, Yale has had numerous alumni and former students go on to become founders of influential business, like William Boeing (Boeing, United Airlines), Briton Hadden and Henry Luce (Time Magazine), Stephen A. Schwarzman (Blackstone Group), Frederick W. Smith (FedEx), Juan Trippe (Pan Am), Harold Stanley (Morgan Stanley), Bing Gordon (Electronic Arts), and Ben Silbermann (Pinterest). Other business people from Yale include former chairman and CEO of Sears Holdings Edward Lampert, former Time Warner president Jeffrey Bewkes, former PepsiCo chairperson and CEO Indra Nooyi, sports agent Donald Dell, and investor/philanthropist Sir John Templeton,

Yale alumni distinguished in academia include literary critic and historian Henry Louis Gates, economists Irving Fischer, Mahbub ul Haq, and Nobel Prize laureate Paul Krugman; Nobel Prize in Physics laureates Ernest Lawrence and Murray Gell-Mann; Fields Medalist John G. Thompson; Human Genome Project leader and National Institutes of Health director Francis S. Collins; brain surgery pioneer Harvey Cushing; pioneering computer scientist Grace Hopper; influential mathematician and chemist Josiah Willard Gibbs; National Women’s Hall of Fame inductee and biochemist Florence B. Seibert; Turing Award recipient Ron Rivest; inventors Samuel F.B. Morse and Eli Whitney; Nobel Prize in Chemistry laureate John B. Goodenough; lexicographer Noah Webster; and theologians Jonathan Edwards and Reinhold Niebuhr.

In the sporting arena, Yale alumni include baseball players Ron Darling and Craig Breslow and baseball executives Theo Epstein and George Weiss; football players Calvin Hill, Gary Fenick, Amos Alonzo Stagg, and “the Father of American Football” Walter Camp; ice hockey players Chris Higgins and Olympian Helen Resor; Olympic figure skaters Sarah Hughes and Nathan Chen; nine-time U.S. Squash men’s champion Julian Illingworth; Olympic swimmer Don Schollander; Olympic rowers Josh West and Rusty Wailes; Olympic sailor Stuart McNay; Olympic runner Frank Shorter; and others.