A new report published by the Sierra Club serves as proof that despite the geography, politics and social norms that divide American cities, a growing number of towns big and small can come together and work towards a common goal: the rejection of fossil fuels in favor of clean, renewable energy sources.

Released just ahead of the Global Climate Action Summit in San Francisco, the 2018 Case Study Report profiles 10 cities from coast to coast that have vowed to transition to 100 percent clean energy. They are Denver, Minneapolis, St. Louis, Orlando, Florida; Concord, New Hampshire; Columbia, South Carolina; Denton, Texas; Fayetteville, Arkansas; Norman, Oklahoma and Santa Barbara, California.

It's a disparate mix — and there's plenty more where these 10 towns came from. Per the Sierra Club, more than 80 cities in the U.S. are moving in the direction of 100 percent clean energy use. A small but growing handful of American cities — Burlington, Vermont; Aspen, Colorado; Eugene, Oregon; and Greensburg, Kansas, to name a few — are already sourcing 70 percent or more of their energy needs from solar, wind, geothermal and the like.

While local commitments to a cleaner future are encouraging and necessary, the good work of the cities profiled in the Sierra Club's report will likely be overshadowed by what's underway at a state level, specifically in California where Senate Bill (SB100) was recently signed by Gov. Jerry Brown. This landmark bill sets the Golden State — the world's fifth largest economy — on track to use only renewable energy by 2045. What's more, Brown kicked things up a v ery large notch by also signing an executive order that commits California to economy-wide carbon neutrality by 2045.

While a state vowing to generate electricity exclusively from renewable sources is huge news in itself, Vox's David Roberts notes that Brown's commitment to complete carbon neutrality is what's really gobsmacking ... and in the best way possible. He calls the executive order the "most significant carbon policy commitment ever. Anywhere. Period."

With this news, Brown not only made a splash in the days leading up to the Global Climate Action Summit but executed a series of pool-clearing cannonballs. "It was so out of left field and yet so profound in its implications that few in the media, or even in California, seem to have fully absorbed it yet," writes Roberts.

The wildly photogenic coastal city of Santa Barbara is one of roughly 20 California communities that have committed to a complete shift away from fossil fuel-derived energy. (Photo: Michael Theis/Flickr)

Santa Barbara: A city in plentiful company

Given all of the attention on California and renewables as of late, it's not surprising that the state is home to nearly 20 of the 80 cities and towns identified by the Sierra Club as striving toward 100 percent clean energy — that's roughly a quarter of them. These cities stretch from Eureka, in Northern California's Redwood Empire, all the way to Chula Visa in southernmost San Diego County. Somewhat in the middle is Santa Barbara, the lone Californian city showcased in this year's Case Study Report.

As the report details, "small, green-minded" Santa Barbara first committed to 100 percent clean energy by 2045 in July 2017. By 2020, this affluent beachfront burg aims to use 50 percent renewable energy in all municipal buildings and operations including at its immensely beautiful county courthouse. The following year, Santa Barbara, in partnership with the county and the neighboring communities of Carpenteria and Goleta, plans to break from a traditional, investor-supported utility arrangement and launch a Community Choice Aggregation (CCA) program.

This program, as the Sierra Club explains, would allow Santa Barbara and its neighbors to "band together to purchase their own energy wholesale and, therefore, exercise more control over their energy options. Through the CCA, decisions about power supply, rates, and incentives are brought to the local level." Once the CCA is enacted, Santa Barbara could immediately see its renewable energy mix jump from its current 32 to 34 percent range to 50 percent clean energy.

Home to the University of Oklahoma, Norman is the only community in the Sooner State that's committed to 100 percent clean energy use. (Photo: Majdan/Flickr)

From the Rockies to the Bible Belt, a shift away from fossil fuels

Moving east, Denver — one of 10 Colorado communities that have vowed to eschew fossil fuels in a historically coal-friendly state —will be powered by 100 percent renewable energy by 2030. Noting that the city is "rising fast as a clean energy star," the Case Study Report details how Denver also plans to reduce carbon emissions by 80 percent by 2050 through its ambitious 80x50 Climate Action plan.

Further east is Fayetteville, Arkansas, a fast-growing college town of 85,000 located in a coal-centric state not exactly known for progressive clean energy and climate policies. Under the leadership of Mayor Lioneld Jason, however, Fayetteville is paving the way in the Natural State as the first — and as of now, only — Arkansas community to commit to 100 percent renewable energy. "I believe we live in a day and time in which we know that climate change poses a very serious and very real threat," says Jason. "And I am proud that we have developed our action plan to address climate change issues."

Across the Oklahoma state line, the mid-sized — and also heavily rural — city of Norman is striving for 100 percent renewable energy across all sectors, including not just electricity but heating and transportation, by 2050. Like Fayetteville, Norman is also a college town and first — and so far the only — community in its respective state to make such a commitment. Oklahoma, by the way, ranks second in the country for installed wind power generation capacity. Here's hoping the winds of change blow beyond Norman and into neighboring cities and towns.

In the Midwest, St. Louis and Minneapolis are two cities that have pledged to shift to 100 percent renewable energy within the coming decades. The former, a longtime hub for big coal, plans to do so by 2035. The latter city is one of three Minnesotan communities — alongside St. Paul and St. Louis Park — with an agenda to bid adieu to fossil fuels. When Minneapolis announced its plan to fully transition to clean energy by 2030 in April 2018, it became the largest city in the Midwest to do so.

"Minneapolis is committed to ensuring that energy remains affordable and that our transition to clean energy meets the needs of those most marginalized and affected by pollution," reads a statement released by the office of Mayor Jacob Frey.

Orlando Mayor Buddy Dyer is an outspoken champion of renewable energy. He's also one of hundreds of American mayors who have vowed to uphold the Paris Agreement. (Photo: Aaron P. Bernstein/Getty Images)

A ray of light in the Sunshine State

Orlando is the largest among a quartet of Florida cities — Largo, St. Petersburg and Sarasota being the others — to embrace 100 percent clean energy.

With Mayor Buddy Dyer, a Democrat, at the wheel, Orlando — the Sunshine State's fourth most populous city and among the most visited tourist destinations in the world — has vowed to make the leap on a municipal operations-wide scale by 2030. Already, a local 24-acre solar farm is powering city hall, all 17 fire departments and police headquarters. By 2050, Orlando will be completely powered by renewable energy.

And as the Sierra Club notes, solar power is an obvious shoo-in for Orlando, a city that helps Florida earn its nickname and then some with an average of 300 days of sunshine per year. But as the report details, a full switch to solar, even in sunshine-drenched Central Florida, isn't always easy:

... as in other parts of the country, the upfront costs of solar infrastructure and concerns about availability can present hurdles to community buy-in. To address these issues, Orlando is working closely with its municipal utility, the Orlando Utilities Commission, to decarbonize its energy offerings and rapidly expand the availability of solar energy, while at the same time creating programs that reduce, defray, or even eliminate the upfront costs for end consumers.

These forward-thinking cities and the others — Denton, Columbia and Concord — are profiled in the 2018 Case Study Report. (You can also view the 2016 and 2017 reports, which showcase clean energy-ready cities including San Diego, Atlanta, Salt Lake City and tiny Abita Springs, Louisiana.)

"Cities are taking meaningful steps to realize a vision for healthy, vibrant, and more equitable communities powered with 100 percent clean energy," says Jodie Van Horn, director of the Sierra Club's Ready For 100 campaign. "A transition to 100 percent clean energy is within reach, and together we can create a new energy economy that transforms not only how we power our country but also who has power to decide what's best for our communities."

As the San Francisco Chronicle reports, a new poll conducted by the United States Conference of Mayors and the Center for Climate and Energy Solutions, found that 57 percent of American cities plan on taking action to slow the impact of global warming at some point this year, whether by shifting away from fossil fuel use or other measures. The same poll shows that 95 percent of American cities have been impacted by climate change.

As a sense of urgency drives change on the local and state levels, the Trump White House has taken a notably regressive stance on all things renewable energy and climate change-related.

"Climate change is too important for us not to act," San Francisco Mayor London Breed told a gathering of mayors in her remarks at the Global Climate Action Conference. "We're already seeing the impacts of global warming here in California and all over our planet."

And nowhere else are those impacts on more explicit display than in the communities deluged by Hurricane Florence.