These 24 Americans are changing the world -- and they're all under 40

The World Economic Forum recently announced its 2016 class of Young Global Leaders — people under the age of 40 who are changing the world — and 24 of the 121 are American.

This year’s Young Global Leaders class includes leaders from an array of backgrounds. Some are famous entertainers, like actor and investor Ashton Kutcher and writer John Green, and others are inventors, CEOs, philanthropists, and scientists working on revolutionary ideas — such as Nina Tandon, who grows human bones with her biotech company, EpiBone.

Once chosen by the WEF, these leaders are a part of the program for five years — they attend meetings, participate in initiatives and research, and work with the rest of the WEF’s community.

Here are the 23 American leaders making a worldwide impact.

Editor’s Note: An earlier version of this story mistakenly omitted James Song. The list has since been updated.

Andy Moon, SunFarmer

The Young Global Leaders

Andy Moon started his work in the solar energy industry in 2009 as a project developer for SunEdison. In 2013, he and a coworker started SunFarmer -- a nonprofit that brings solar power to developing countries -- with the help of a $2 million grant from a SunEdison foundation.

SunFarmer has completed more than 100 solar energy projects so far in Nepal, its pilot country, powering schools and health clinics as well as providing relief to victims following a pair of earthquakes last spring.

By 2020, SunFarmer's goal is to power 4,000 hospitals, schools and water projects around the world.

Aria Finger, DoSomething.Org

The Young Global Leaders

After graduating from college in 2005, Aria Finger joined the nonprofit to try to change the way young people give back to their communities. The organisation has since grown from five employees to 55, and in the past decade it has helped 4.7 million young people started campaigns in their hometowns.

Six months ago, Finger was promoted to CEO. Her most recent campaign, Keep Guns Off Campus, encourages students to pressure their college presidents to take a stand against having guns on campus.

Ashton Kutcher, THORN: Digital Defenders of Children

The Young Global Leaders

The actor, producer, and tech investor started the DNA Foundation in 2011 with then-wife Demi Moore with the goal of ending child sex slavery. The company rebranded a year later to 'Thorn: Digital Defenders of Children' with a more specific focus: technology's role in the sexual exploitation of children.

With the help of partners such as Facebook, Tumblr, and Microsoft, Thorn has been battling Internet-enabled sexual abuse and providing support to victims. This past November, Kutcher announced that the organisation would open an innovation lab that will allow data analysts and scientists to think up new technologies to deter online predatory behaviour toward children.

Avid Larizadeh-Duggan, Google Ventures

The Young Global Leaders

Avid Larizadeh-Duggan is one of the two remaining partners left at Google Ventures in Europe, a group created by the company to invest $100 million in startups.

Larizadeh-Duggan is the cofounder of online jewellery company Boticca -- recently acquired by Wolf & Badger -- and she also leads educational programming nonprofit in the UK and is an advisor for Founders4School and the Breteau Foundation.

Danae Ringelmann, Indiegogo

The Young Global Leaders

Indiegogo was founded by Danae Ringelmann as a crowdfunding platform that allows entrepreneurs to raise money without the help of banks or venture firms. Since its start in 2007, projects featured on the site have raised more than $800 million.

On International Women's Day, Ringelmann announced Indiegogo would be partnering with companies such as Dell Women's Entrepreneur Network and Girls In Tech to launch an initiative that encourages women to start their own projects and businesses.

David Bray, Federal Communication Commission

The Young Global Leaders

David Bray started out in tech at age 15, working on computer simulations for the Department of Energy. He had his first military security clearance before he turned 18.

Bray has held an array of academic and public service positions since, and in 2013 he was named chief information officer of the FCC and given the task of running a team of 35 full-time employees and 200 contractors.

Most recently, Bray started an ambitious project to bring the FCC's infrastructures to a cloud-based system.

Dhivya Suryadevara, General Motors

The Young Global Leaders

Dhivya Suryadevara manages more than $80 billion in assets as the CEO of GM Asset Management at General Motors, a post she's held since 2014.

Last summer, she was also promoted to General Motors' vice president of finance and treasurer -- taking responsibility for the company's capital planning and worldwide banking, among other tasks.

James Song, Faircap Partners

The Young Global Leaders

James Song is the cofounder and managing principal at Faircap Partners, an investment firm focused on the burgeoning economy of Myanmar -- the developing Southeast Asian nation of about 55 million people. The company calls the country, whose economy is growing at more than 8% annually, the 'last great frontier for capitalism.'

Prior to founding Faircap, Song served as a medical researcher in Uganda on a Fulbright scholarship. While in Uganda, the Harvard alum, who also holds a masters in nerouscience from University College London, 'pioneered the use of empirically based, non-pharmacological HIV interventions at Makerere University Hospital.' He also started the nation's first polyethylene recycling facility.

Joe Gebbia, Airbnb

Joe Gebbia

Joe Gebbia cofounded Airbnb in 2008 when he and his roommate were struggling with ways to come up with rent money. Since then, the person-to-person home and apartment rental company has grown to provide services in over 30,000 cities and is valued at more than $25 billion. Gebbia alone is worth $3.3 billion.

In February, Gebbia led a TED Talk on building trust with his company's customers. 'We bet our whole company on the hope that, with the right design, people would be willing to overcome the stranger-danger bias,' he said.

John Green, Author

The Youth Global Leaders

The Indianapolis-born author has written four New York Times Best Sellers: 'Looking for Alaska,' 'An Abundance of Katharines,' 'Paper Towns,' and 'The Fault in Our Stars.'

The latter two books have both been made into successful feature films, while 'Looking for Alaska' has been stalled for years at Paramount, much to Green's frustration.

In March, he took a trip to Jordan to visit Syrian Refugees with the UN Refugee Agency.

Julie Yoo, Kyruus

The Youth Global Leaders

Julie Yoo is a cofounder and the chief product officer of Kyruus, a company that uses data to help healthcare professional and hospitals match their patients with physicians. The company has raised nearly $60 million in funding, including a $25 million round in September.

Yoo is bullish about the company's future, saying, 'We see Kyruus as the leader of the next big category in healthcare IT: patient access.'

Leslie Dewan, Transatomic Power Corporation

The Young Global Leaders

While studying at MIT, Leslie Dewan and a classmate discovered something the nuclear industry had given up on long ago: the molten salt reactor, a more efficient and safe alternative to the reactors in use today.

They started Transatomic Power and designed an updated version called the Waste Annihilating Molten Salt Reactor, which will burn liquid uranium fuel instead of solid fuel, decreasing the chance of a meltdown. It will also create 75 times more electricity per ton of uranium. Dewan, who ultimately hopes to diminish the use of fossil fuels, plans to blueprint a test plant and move forward with a prototype facility at a national laboratory by 2020.

Michael Lefenfeld, SiGNa Chemistry INC.

The Young Global Leaders

Michael Lefenfeld came up with the idea for SiGNa Chemistry in 2002 after his grandfather asked him to solve a problem: He wanted something that would work like an air freshener, but for the toilet.

After partnering with a chemist, he built SiGNa, which manufactures safe, user-friendly alkali metals -- which are typically very combustible -- for larger-scale chemical reactions.

SiGNa's more environmentally friendly products are now being applied far beyond the bathroom, including for oil recovery, petrochemical refining, pharmaceutical manufacturing, alternative energy production, and speciality chemical processing.

Monica Yunus, Sing for Hope

The Young Global Leaders

Born in Bangladesh but raised in New Jersey, Monica Yunus started her career as an opera singer after attending Juilliard. She cofounded and is the director for Sing For Hope -- a nonprofit organisation based in New York that brings arts programming to underprivileged communities.

The organisation is well-known for its Sing for Hope Pianos, in which decorated pianos are placed throughout New York City for public use.

Nina Tandon, EpiBone

The Young Global Leaders

Nina Tandon is the CEO of EpiBone, a biotech company she cofounded in 2012 that is trying to revolutionise how we treat bone injuries and ailments. The company uses stem cells and a special incubator to grow human bones that doctors can use in surgeries instead of taking them from another part of the body or using the donor bones.

Aside from EpiBone, Tandon is also the co-author of 'Super Cells: Building with Biology,' a TED Senior Fellow, and an adjunct professor of electrical engineering at Cooper Union.

Penny Abeywardena, Mayor's Office of the City of New York

The Young Global Leaders

Prior to her time working for New York City Mayor Bill De Blasio as the commissioner of international affairs, Penny Abeywardena worked for the Clinton Foundation as the director of girls and women integration.

As the commissioner, Abeywardena works as the liaison between the New York and diplomatic communities, foreign governments, the United Nations, and US Department of State.

Since starting the job in 2014 Abeywardena's goal has been to 'create a global platform from which to promote what's working in New York City, but also engage this diplomatic community with its local immigrant communities.'

Rohit Chopra, Lazard

The Young Global Leaders

Rohit Chopra joined Lazard in 1999 as the youngest managing director for the financial advisory and asset management firm. Chopra now manages the $9.2 billion Lazard Emerging Markets Equity Porfolio -- one of the firm's largest -- which is beating 93% of its competitors this year with a value-focused approach toward investments in countries like Brazil, South Africa, and Turkey.

Roland G. Fryer, Jr., Harvard University

The Young Global Leaders

Before becoming an award-winning Harvard University economics professor, Roland G. Fryer wasn't sure he would make it out of his hometown of Daytona Beach, Forida, where he grew up around crack dealers.

While many of his best friends wound up in prison or dead, by age 30 Fryer became the youngest African-American economics professor to receive tenure at Harvard, thanks in part to novel studies that examine racial inequality and education.

Last year he became the first black recipient of the John Bates Clark Medal, the second-highest economics honour after the Nobel Prize. His current projects include studying how high-quality charter schools affect students' earnings later in life and researching which colleges disadvantaged students prefer to attend.

Sam Altman, Y Combinator

The Young Global Leaders

Sam Altman cofounded location-sharing service Loopt in 2005 with the help of seed funding from Silicon Valley incubator Y Combinator. He sold Loopt in 2012 for nearly $45 million.

Two years later Altman took over as CEO of the vaunted tech incubator, which has helped spawn Airbnb, Dropbox, and Reddit. Since taking the reins, Altman has expanded the company to include a fellowship program, a VC arm, and a research lab.

His goal is to make Y Combinator 10 times bigger: 'We were talking about how do we add another zero, go from 200 companies to 2,000.'

Sarah Daubenspeck, Accenture

The Young Global Leaders

Sarah Daubenspeck is the managing director of the CFO and Enterprise Value group at Accenture, where she specialises in the healthcare, high tech, and products sectors.

Daubenspeck, who joined the workforce amid the 'dot com' implosion of the early 2000s, credits her swift corporate rise to a head-down, hardworking mentality instilled by her grandfather. 'There is not a magic secret. It's been sheer hard work. Sometimes I worked hard. Sometimes I worked smart. Sometimes I had to learn the difference,' she wrote on The Huffington Post.

She aspires to be a voice in supporting female education through business and policy actions.

Seth Moulton, US House of Representatives

The Young Global Leaders

Massachusetts-born Seth Moulton has served four tours in Iraq -- where he earned two medals -- and was elected to congress in 2014. The congressman's main focuses are the economic growth for Massachusetts families and improving veterans' healthcare.

Moulton's personal difficulties with Veterans Affairs hospitals, which have also had well-documented failings at a national level, led him to create a small package of bills in hopes of improving their quality.

In November, Moulton opened his home to a Syrian refugee after Massachusetts Gov. Charlie Baker said he didn't want the refugees coming to the state.

Shivani Siroya, InVenture

The Young Global Leaders

When Shivani Siroya founded microfinance firm InVenture in 2011, she did it with the hope that small business owners around the would have a better chance at borrowing money instead of getting denied by banks for a single criteria: having a low credit score.

InVenture's proprietary software, uploaded by a user on their phone, monitors 10,000 aspects of a person's level of responsibility before they're considered for a loan. The idea came to Siroya after working in emerging markets and microfinance for investment banks as well as the UN and UNICEF.

InVenture only operates in Eastern Africa, India, and South Africa, where Soriya found that 2.5 billion people don't have a credit score.

Vanessa Kerry, Seed Global Health

The Young Global Leaders

Vanessa Kerry, a critical care physician and the daughter of US Secretary of State John Kerry, founded the nonprofit Seed Global Health in 2012 to better train health professionals in developing parts of the world.

'I realised that something needed to change; there had to be a way to provide better healthcare in a sustainable way in countries that are resource constrained,' she said at a recent fundraiser. 'This is a solution to improving the health of the world.'

The organisation, which trained 7,200 medical professionals in such as Uganda, Malawi, and Tanzania over the past two years, plans on expanding services to two more countries this year.

Yao Zhang, Roboterra

The Young Global Leaders

Roboterra CEO Yao Zhang had one goal: Teach kids around the world to code. To execute this ambition, Zhang created the Origin Kit, a $319 individual box full of parts that students assemble into an interactive robot, and Castle Rock, a coding platform to program the robot.

With these creations Zhang aims to bring college-level learning to middle schoolers. This past fall, after partnering with schools in China, Roboterra ran its first pilot program with 30 students in Silicon Valley.

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