Climate Mayors Statement on President Trump’s Revocation of California Clean Air Act Waiver

September 18, 2019 – Today, a spokesperson from Climate Mayors issued the following statement around the Trump administration’s revocation of California’s waiver under the Clean Air Act:

“President Trump’s announcement today that the Environmental Protection Agency (EPA) will rescind California’s authority to regulate pollution from automobiles runs in direct opposition to the EPA’s stated mission and the federal Clean Air Act (CAA), and will be harmful to our residents’ physical and financial health – impacts that we simply cannot afford in the face of a growing climate crisis. We need carmakers to harness their innovation and accelerate the nation’s progress toward a new, clean era of transportation. Instead, today’s decision will stall the progress we’ve already made in cleaning up our transportation sector, the highest-polluting sector in the United States.

Under the CAA, California has the authority to adopt stronger pollution standards than those set by the federal government. Other states have not been granted similar authority but can opt to follow California’s motor vehicle emission regulations. Maintaining state authority to protect local communities from pollution has strong support from Climate Mayors across the country who want to take meaningful and ambitious action toward fighting climate change. The administration’s ironic assault on states’ rights will directly harm the more than 118 million people living in 14 states and the District of Columbia that have adopted more stringent vehicle pollution standards in order to protect the health of their communities.

But whether or not the White House is on board, this much is clear: the automotive industry is already producing cleaner and, increasingly, more zero-emissions vehicles – not just because they’re good for the environment, but also because of the economic and public health benefits that follow. That’s why companies such as Honda, Ford, Volkswagen, and BMW have already expressed their commitment to maintaining strong emissions standards established in 2012 and currently under threat by the Trump administration. And it’s also why Climate Mayors across the country are making strides in deploying clean vehicles in their cities. The Climate Mayors Electric Vehicle Purchasing Collaborative is bringing cities to the table and deploying electric vehicles to streets from coast-to-coast – and no decision from the White House will stop our progress.

As Climate Mayors representing over 71 million Americans in over 430 cities across the United States, we are committed to leading on climate action, no matter who occupies the Oval Office. We will continue our efforts to hasten the transition to more efficient and zero-emissions vehicles because we know it’s what’s best for our residents, our economy, and our environment.”

Climate Mayors Statement in Support of Strong Auto Efficiency Standards

Climate Mayors responds to U.S. Environmental Protection Agency (EPA) Administrator Scott Pruitt’s April 2, 2018 announcement of proposed weakening of corporate average fuel economy (CAFE) standards

As mayors representing 69 million Americans, across 47 states (and the District of Columbia and Puerto Rico), with millions of vehicles on our roads, we strongly support the current federal standards on vehicle fuel efficiency and oppose the Trump Administration’s efforts to roll back this important policy.  Today’s announcement leaves the health of American families hanging in the balance while creating uncertainty in the automotive market. The standards adopted by the US EPA in 2011 are saving American drivers money at the gas pump, keeping the country competitive in a sector trending toward zero emissions innovation, and cleaning up the air we all breathe.

As mayors, we are bound by our common commitment to lead in the fight against climate change. Last year 30 Climate Mayors released a joint Electric Vehicle Request for Information (EV RFI) proving to car companies that if they build zero emissions vehicles, we will buy them. These first 30 cities put forward a combined 114,000 vehicles representing $10 billion in industry value. We want these vehicles because they save us money, offer new technologies and services, and protect local communities from harmful air pollution.

We will continue our efforts to hasten the transition to more efficient and zero emissions vehicles. We had long viewed the federal government as a partner on clean cars, but we won’t let it take us backwards.

Climate Mayors Submit Comments on Proposed Repeal of Clean Power Plan

244 U.S. Mayors from 48 states and territories, representing over 52 million Americans, strongly oppose EPA’s proposed repeal of Clean Power Plan

In a comment letter re-submitted today to the US Environmental Protection Agency (EPA), 244 mayors from 48 states and territories voice opposition to efforts by the Trump administration and EPA Administrator Scott Pruitt to dismantle the Clean Power Plan, as it would have devastating health and economic impacts on their communities, including exposing Americans to increased air pollution, worsening climate change, and more extreme weather events.  This comment letter was originally submitted to US EPA on February 20, 2018 with 233 signatories. Additional mayors wishing to add their support to this comment letter should email: to be included.


March 27, 2018

By electronic mail ( and first class mail

Administrator Scott Pruitt
Environmental Protection Agency
EPA Docket Center (EPA/DC)
Mail Code 28221T
Attention Docket ID No. EPA-HQ-OAR-2017-0355
1200 Pennsylvania Avenue, NW
Washington, DC 20460

Administrator Pruitt:

As mayors from 244 U.S. cities, we submit this letter of comment to oppose the Environmental Protection Agency’s proposed repeal of the Clean Power Plan, Repeal of Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units.

Collectively, we represent over 52 million residents, in 48 states & territories across the country. We strongly oppose the proposed repeal of the Clean Power Plan, which would put our citizens at risk and harm our efforts to address the urgent threat of climate change.

Climate Change is Global but Impacts are Felt Locally

Communities across the country are experiencing the effects of climate change today: sea level rise; hotter, longer, and more frequent heat waves; increased extreme weather; and many other harmful impacts. There is broad agreement that the future economic costs of climate change should not be overlooked. On our current path, the annual cost of coastal storm damage is expected to climb to as high as $35 billion by the 2030s; coastal property valued at $66 to $106 billion will likely be underwater by 2050.

No one is insulated from the impacts of climate change – people in cities of all sizes, along with suburban and rural communities are all at risk. Residents of our communities have experienced harmful impacts of climate change such as dirtier air, increased heat-related illnesses and deaths, damaged and disappearing coastlines, longer droughts and other strains on water quantity and quality, and increasingly frequent and severe storms and wildfires.

Reducing greenhouse gas emissions is essential to protect our citizens against the worst impacts of climate change. A peer reviewed study conducted by EPA projected stark differences between a world in the year 2100 where global warming averages 2 degrees Celsius—a goal for which the Clean Power Plan is critical—and one in which global warming averages 4 degrees Celsius: 57,000 fewer domestic deaths per year due to poor air quality; 12,000 fewer domestic deaths per year from extreme heat and cold in 49 U.S. cities; up to $6.4 billion in avoided annual adaptation costs from severe precipitation in 50 U.S. cities; $3.1 billion in avoided annual damages and adaptation costs from sea level rise and storm surge on the coasts; and up to $2.5 billion in avoided damages from inland flooding.

Repealing the Clean Power Plan Would Slow Local Efforts to Address Climate Change

Not only are climate change impacts felt locally — our communities are also where climate change adaptation and mitigation efforts are being implemented. Urban, suburban, and rural communities across the country are reducing their contributions to greenhouse gas emissions by investing in energy efficiency, committing to the use of clean energy resources, and reducing reliance on fossil-fueled energy sources—efforts that protect against climate change, and also support clean air and a vibrant clean energy economy.

But the legal authority of cities and other municipalities generally extends only as far as their state governments and federal law allow, and as a result, our local efforts to address climate change are highly sensitive to national policies like the Clean Power Plan, which shape markets, steer state action, and have large direct impacts on nationwide emissions.

We would benefit from the support and certainty that a federal framework for reducing the power sector’s greenhouse gas emissions could provide. The Clean Power Plan, by providing such a framework, would enhance ongoing local efforts and enable new local initiatives to improve public health, increase air quality, and reduce greenhouse gas emissions through energy innovation.

We would like to reiterate a statement that more than 25 mayors delivered during the course of the Clean Power Plan development: “[W]e cannot act alone. We need the federal government to provide a path forward to making meaningful reductions in carbon pollution while preparing for the impacts of climate change.”

As 244 mayors of communities across the U.S., representing over 52 million residents in 48 states & territories we strongly oppose the repeal of the Clean Power Plan, which would put our citizens at risk and undermine our efforts to prepare for and protect against the worst impacts of climate change.


Mayor Peggy McQuaid
Albany, CA

Mayor Kathy Sheehan
Albany, NY

Mayor Tim Keller
Albuquerque, NM

Mayor Ed Pawlowski
Allentown PA

Mayor Gary Goosman
Amesville, OH

Mayor Sofia Pereira
Arcata, CA

Mayor Nancy Kaboolian
Ardsley, NY

Mayor Esther Manheimer
Asheville, NC

Mayor Steve Skadron
Aspen, CO

Mayor Keisha Lance Bottoms
Atlanta, GA

Mayor Steve Adler
Austin, TX

Mayor Catherine E. Pugh
Baltimore, MD

Mayor Kelli Linville
Bellingham, WA

Mayor Jesse Arreguin
Berkeley, CA

Mayor Robert J. Donchez
Bethlehem, PA

Mayor Michael P. Cahill
Beverly, MA

Mayor Lili Bosse
Beverly Hills, CA

Mayor Randall Woodfin
Birmingham, AL

Mayor Leslie Hager-Smith
Blacksburg, VA

Mayor David H. Bieter
Boise, ID

Mayor Martin J. Walsh
Boston, MA

Mayor Suzanne Jones
Boulder, CO

Mayor Eric Mamula
Breckenridge, CO

Mayor Joseph P. Ganim
Bridgeport, CT

Mayor W. Clarke Conway
Brisbane, CA

Mayor Brenda J. Hess
Buchanan, MI

Mayor Byron W. Brown
Buffalo, NY

Mayor Miro Weinberger
Burlington, VT

Mayor Edwin García Feliciano
Camuy, PR

Mayor Robert J. Moffatt, VMD
Cape May Point, NJ

Mayor Jim Brainard
Carmel, IN

Mayor Lydia E. Lavelle
Carrboro, NC

Mayor Mike Webb
Carver, MN

Mayor Pam Hemminger
Chapel Hill, NC

Mayor John Tecklenburg
Charleston, SC

Mayor Scott Rogers
Charles Town, WV

Mayor Andy Berke
Chattanooga, TN

Mayor Chuck Cahn
Cherry Hill, NJ

Mayor Rahm Emanuel
Chicago, IL

Mayor Mary Casillas Salas
Chula Vista, CA

Mayor John Cranley
Cincinnati, OH

Mayor Ted Terry
Clarkston, GA

Mayor Frank G. Jackson
Cleveland, OH

Mayor Patrick Wojahn
College Park, MD

Mayor Brian Treece
Columbia, MO

Mayor Steve Benjamin
Columbia, SC

Mayor Jeff Katz
Cooperstown, NY

Mayor Raul Valdes-Fauli
Coral Gables, FL

Mayor Carla Condon
Corte Madera, CA

Mayor Brian Tobin
Cortland, NY

Mayor Biff Traber
Corvallis, OR

Mayor Mark Landman
Cotati, CA

Mayor Roger W. Foster
Crete, NE

Mayor Darcy Paul
Cupertino, CA

Mayor Mike Rawlings
Dallas, TX

Mayor Juslyn Manalo
Daly City, CA

Mayor Robb Davis
Davis, CA

Mayor Cary Glickstein
Delray Beach, FL

Mayor Michael B. Hancock
Denver, CO

Mayor Josh Maxwell
Downingtown, PA

Mayor David Haubert
Dublin, CA

Mayor Roy D. Buol
Dubuque, IA

Mayor Emily Larson
Duluth, MN

Mayor Stephen M. Schewel
Durham, NC

Mayor Brad Cohen
East Brunswick Township, NJ

Mayor Mark S. Meadows
East Lansing, MI

Mayor Nancy Tyra-Lukens
Eden Prairie, MN

Mayor James Hovland
Edina, MN

Mayor Dave Earling
Edmonds, WA

Mayor David Kaptain
Elgin, IL

Mayor John J. Bauters
Emeryville, CA

Mayor Lucy Vinis
Eugene, OR

Mayor Stephen H. Hagerty
Evanston, IL

Mayor Karl W. Kassel
Fairbanks North Star Borough, AK

Mayor Ed Malloy
Fairfield, IA

Mayor Peter Lindstrom
Falcon Heights, MN

Mayor David Tarter
Falls Church, VA

Mayor Colleen Mahr
Fanwood, NJ

Mayor Lioneld Jordan
Fayetteville, AR

Mayor David Coulter
Ferndale, MI

Mayor Lindy Peters
Fort Bragg, CA

Mayor Wade Troxell
Fort Collins, CO

Mayor John P. “Jack” Seiler
Fort Lauderdale, FL

Mayor Thomas C. Henry
Fort Wayne, IN

Mayor Bob Scott
Franklin, NC

Mayor Lily Mei
Fremont, CA

Mayor Gary Wilkinson
Frisco, CO

Mayor Lauren B. Poe
Gainesville, FL

Mayor J Kachen Kimmell
Gambier, Ohio

Mayor Karen Freeman-Wilson
Gary, IN

Mayor Tammy Stempel
Gladstone, OR

Mayor Bruce J Packer
Glen Rock, NJ

Mayor Marjorie Sloan
Golden, CO

Mayor Paula Perotte
Goleta, CA

Mayor Rosalynn Bliss
Grand Rapids, MI

Mayor Emmett V. Jordan
Greenbelt, MD

Mayor Peter Swiderski
Hastings-on-Hudson, NY

Mayor Harry Kim
County of Hawai’i, HI

Mayor Barbara Halliday
Hayward, CA

Mayor Nancy Rotering
Highland Park, IL

Mayor Gayle Brill Mittler
Highland Park, NJ

Mayor Ravinder S. Bhalla
Hoboken, NJ

Mayor Josh Levy
Hollywood, FL

Mayor Alex Morse
Holyoke, MA

Mayor Kirk Caldwell
Honolulu, HI

Mayor Paul Blackburn
Hood River, OR

Mayor Sylvester Turner
Houston, TX

Mayor Candace B. Hollingsworth
Hyattsville, MD

Mayor Serge Dedina
Imperial Beach, CA

Mayor Jim Throgmorton
Iowa City, IA

Mayor Svante Myrick
Ithaca, NY

Mayor Pete Muldoon
Jackson, WY

Mayor Sly James
Kansas City, MO

Mayor Bernard P. Carvalho Jr
Kauai, HI

Mayor John Antaramian
Kenosha, WI

Mayor Steve Noble
Kingston, NY

Mayor Madeline Rogero
Knoxville, TN

Mayor Tim Kabat
La Crosse, WI

Mayor Christine Berg
Lafayette, CO

Mayor Robert Blais
Lake George Village, NY

Mayor Adam Paul
Lakewood, CO

Mayor Danene Sorace
Lancaster, PA

Mayor William J Sprague
Lapeer, MI

Mayor Ken Miyagishima
Las Cruces NM

Mayor Craig A. Moe
Laurel, MD

Mayor Stuart Boley
Lawrence, KS

Mayor Theodore Becker
Lewes, DE

Mayor Robert Garcia
Long Beach, CA

Mayor Adam Schneider
Long Branch, NJ

Mayor Eric Garcetti
Los Angeles, CA

Mayor Greg Fischer
Louisville, KY

Mayor Paul Soglin
Madison, WI

Mayor Joyce Craig
Manchester, NH

Mayor Amy Howorth
Manhattan Beach, CA

Mayor Barry J. Greenberg
Maplewood, MO

Mayor Alan M. Arakawa
Maui, HI

Mayor Stephanie M. Burke
Medford, MA

Mayor Jim Strickland
Memphis, TN

Mayor Dan Gelber
Miami Beach, FL

Mayor Gurdip Brar, Ph.D.
Middleton, WI

Mayor Daniel T. Drew
Middletown, CT

Mayor Sean Strub
Milford, PA

Mayor Jeff Silvestrini
Millcreek, UT

Mayor Tom Barrett
Milwaukee, WI

Mayor Jacob Frey
Minneapolis, MN

Mayor John Engen
Missoula, MT

Mayor Mary O’Connor
Monona, WI

Mayor Jamie Irons
Morro Bay, CA

Mayor Arlene Burns
Mosier, OR

Mayor Lenny Siegel
Mountain View, CA

Mayor Frederick T. Courtright
Mount Pocono, PA

Mayor Jill Techel
Napa, CA

Mayor Megan Barry
Nashville, TN

Mayor Kristopher Larsen
Nederland, CO

Mayor Jon Mitchell
New Bedford, MA

Mayor Donna D. Holaday
Newburyport, MA

Mayor Toni N. Harp
New Haven, CT

Mayor Mitchell J. Landrieu
New Orleans, LA

Town Supervisor Neil Bettez
New Paltz, NY

Mayor Bill de Blasio
New York City, NY

Mayor Paul A. Dyster
Niagara Falls, NY

Mayor Lynne Miller
Norman, OK

Mayor David J. Narkewicz
Northampton, MA

Mayor Smith Joseph D.O., Pharm.D.
North Miami, FL



Mayor Don Hammond
Nyack, New York

Mayor Libby Schaaf
Oakland, CA

Mayor Johnny Johnston
Ojai, CA

Mayor Cheryl Selby
Olympia, WA

Mayor Buddy Dyer
Orlando, FL

Mayor Victoria Gearity
Ossining, NY

Mayor Andy Beerman
Park City, UT

Mayor Donald R. Grebien
Pawtucket, RI

Mayor Frank C. Ortis
Pembroke Pines, FL

Mayor Jim Kenney
Philadelphia, PA

Mayor Cindy Perry
Pittsboro, NC

Mayor Jeremy Johnson
Pittsburg, KS

Mayor William Peduto
Pittsburgh, PA

Mayor Kurt R. Metzger
Pleasant Ridge, MI

Mayor Ethan Strimling
Portland, ME

Mayor Ted Wheeler
Portland, OR

Mayor Deborah Stinson
Port Townsend, WA

Mayor Jorge O. Elorza
Providence, RI

Mayor Paul Kuhns
Rehoboth Beach, DE

Mayor Hillary Schieve
Reno, NV

Mayor Tom Butt
Richmond, CA

Mayor Levar M. Stoney
Richmond, VA

Mayor Lovely Warren
Rochester, NY

Mayor Darrell Steinberg
Sacramento, CA

Mayor Jacob Day
Salisbury, MD

Mayor Jackie Biskupski
Salt Lake City, UT

Mayor Ron Nirenberg
San Antonio, TX

Mayor Kevin Faulconer
San Diego, CA

Mayor Mark Farrell
San Francisco, CA

Mayor Sam Liccardo
San José, CA

Mayor Pauline Russo Cutter
San Leandro, CA

Mayor Heidi Harmon
San Luis Obispo, CA

Mayor Rick Bonilla
San Mateo, CA

Mayor David J. Terrazas
Santa Cruz, CA

Mayor Javier M. Gonzales
Santa Fe, NM

Mayor Ted Winterer
Santa Monica, CA

Mayor Shelli Freeland Eddie
Sarasota, FL

Mayor Chris Lain
Savanna, IL

Mayor Jenny Durkan
Seattle, WA

Mayor Michael Gonnelli
Secaucus, NJ

Mayor George Van Dusen
Skokie, IL

Mayor Ken Wray
Sleepy Hollow, NY

Mayor Scott Saunders
Smithville, TX

Mayor Matthew R. Larson
Snoqualmie, WA

Mayor Jeffrey Slavin
Somerset, MD

Mayor Dana S. Hilliard
Somersworth, NH

Mayor Joseph A. Curtatone
Somerville, MA

Mayor Pete Buttigieg
South Bend, IN

Mayor Philip Stoddard
South Miami, FL

Mayor Sheena C. Collum
South Orange Village, NJ

Mayor Domenic J. Sarno
Springfield, MA

Mayor David Martin
Stamford, CT

Mayor Donald M. Hahn
State College, PA

Mayor Lyda Krewson
St. Louis, MO

Mayor Michael Tubbs
Stockton, CA

Mayor Melvin Carter
St. Paul, MN

Mayor Glenn Hendricks
Sunnyvale, CA

Mayor Daniel Dietch
Surfside, FL

Mayor Tim Kearney
Swarthmore, PA

Mayor Thomas Fromm
Swedesboro, NJ

Mayor Kate Stewart
Takoma Park, MD

Mayor Drew Fixell
Tarrytown, NY

Mayor Sean Murphy
Telluride, CO

Mayor Jim Carruthers
Traverse City, MI

Mayor Jonathan Rothschild
Tucson, AZ

Mayor Brian P. Stack
Union City, NJ

Mayor Shelley Welsch
University City, MO

Mayor Dave Chapin
Vail, CO

Mayor Kevin J. Ryan
Verona, NJ

Mayor Muriel Bowser
Washington, DC

Mayor Lowell Hurst
Watsonville, CA

Mayor John Heilman
West Hollywood, CA

Mayor John Dennis
West Lafayette, IN

Mayor Daniel J. Stermer
Weston, FL

Mayor Jeri Muoio
West Palm Beach, FL

Mayor Christopher Cabaldon
West Sacramento, CA

Mayor Daniel Corona
West Wendover, NV

Mayor Bud Starker
Wheat Ridge, CO

Mayor Thomas Roach
White Plains, NY

Mayor Mike Spano
Yonkers, NY

Mayor Amanda Marie Edmonds
Ypsilanti, MI

The comment letter was originally released on February 20, 2018 (5:00am PST) with 233 signatories. Updated signatories as of 11:00 am PST on March 27, 2018. Mayors wishing to add their support to this comment letter should email: before the closing of the EPA Comment Period on April 26, 2018.

279 Climate Mayors across the United States now committed to adopting the Paris agreement goals in their cities

LOS ANGELES — In the week since the President pulled the U.S. from the Paris Climate Agreement, 279 Climate Mayors — a peer-to-peer network Mayor Garcetti co-founded in 2014 — have pledged to adopt, honor, and uphold the Paris Agreement goals in their cities.

When the President announced the withdrawal on June 1, 61 Climate Mayors spoke up together in support of the agreement. One week later, the number of Climate Mayors more than quadrupled in size, representing nearly one in five Americans.

Mayor Garcetti and the Climate Mayors responded forcefully to the Administration’s decision to leave the Paris Agreement last week, each making a strong commitment to uphold its standards in their own cities.

“Last week, Democratic and Republican mayors from cities across America came together to say ‘Enough’ — we will not let the future of our world be jeopardized by inaction at the very top,” said Mayor Garcetti. “Now, mayors from every corner of our nation are joining the call to action, and uniting to carry the fight against climate change forward in our cities.”

The Climate Mayors now include nine of the 10 largest cities in America — New York, Los Angeles, Chicago, Houston, Philadelphia, Phoenix, San Diego, Dallas, and San Jose — along with hundreds of additional cities large and small, from Boston to Knoxville to the City of Miami, in both red and blue states. In all, the 279 Climate Mayors now represent 59 million Americans from 42 states.

“This is a top priority for the people of Boston and the American people,” said Boston Mayor Martin J. Walsh. “We see the impacts of climate change every day in the streets and homes of our cities — the extreme heat, flooding, and increasing health issues. It’s our responsibility to act, and I’m proud to stand among the growing number of Climate Mayors fighting for our residents.”

“We believe that The City of Miami is ground zero for climate change and sea level rise,” said Miami Mayor Tomas Regalado. “Now, more than ever, we are undeterred and will vigorously pursue our commitment to this fight. This is not just about ‘the here and now,’ but for generations to come.”

“Protecting the climate is not a choice between our environment and our economy,” said Knoxville Mayor Madeline Rogero. “As we have shown in Knoxville, we can strengthen both while making Knoxville a better community. No matter the attitude of the president, we will continue to advance our local values by upholding the principles and commitment of the Paris Agreement.”

In Los Angeles, Mayor Garcetti has led the effort to make L.A. the most sustainable city in America. In April 2015, he introduced the city’s first ever Sustainable City pLAn, a comprehensive roadmap that lays out measurable long-term goals for efforts like conserving water, creating green jobs, expanding the use of electric vehicles, and reducing greenhouse gas emissions by 45% below 1990 levels by 2025, and 80% by 2050. The City is on track to meet 90% of the pLAn’s 2017 goals.

You can see the text, map of and full list of signatories to the Climate Mayors commitment to adopt the Paris Agreement goals. To learn more about Climate Mayors, visit can also engage with Climate Mayors on FacebookTwitter and Medium.

Mayor Garcetti is the co-founder of the Climate Mayors (also known as the Mayors National Climate Action Agenda, or MNCAA), a network of 289 U.S. cities representing more than 62 million Americans — working together to strengthen local efforts for reducing greenhouse gas emissions and supporting efforts for binding federal and global-level policymaking. Earlier this year, Mayor Garcetti led the release of an EV RFI with 30 MNCAA cities to demonstrate potential demand for over 114,000 electric vehicles, trucks, and equipment for cities. Mayor Garcetti is also Vice Chair of the C40 Cities Climate Leadership Group, an international network of the world’s megacities taking action to reduce greenhouse gas emissions, and he has signed the Covenant of Mayors for Climate and Energy.

Bloomberg CityLab: Can Cities Actually Meet the Paris Commitments on Their Own?

Think of the Paris climate accord as a delicate scale. Every nation works to meet carefully co-determined carbon cuts, holding one another accountable towards the utterly un-simple goal of limiting catastrophic global warming. By withdrawing the U.S., President Trump has lifted a critical weight from one end of this scale. How and whether it can right itself is an open question.