Risa Wechsler uses computer simulations of the entire universe to explore questions about our existence on the largest scales.

Jennifer Wilcox works on ways to test and measure methods of trace metal and carbon capture, to mitigate the effects of fossil fuels on our planet.

Physicist Geoffrey West believes that complex systems from organisms to cities are in many ways governed by simple laws -- laws that can be discovered and analyzed.

Alok Sharma is a British politician, Cabinet Minister and President-Designate of COP26, the 26th United Nations Climate Change Conference.

Bertrand Piccard circumnavigated the Earth in a hot-air balloon. Now he wants to circle it in an airplane powered only by solar energy.

A leading interpreter of Mahler and Beethoven, Benjamin Zander is known for his charisma and unyielding energy -- and for his brilliant pre-concert talks.

Jason Pontin is the editor-in-chief and publisher of MIT Technology Review.

Sarah Rugheimer looks for signs of life on other planets by studying the telltale chemical signatures on distant planets.

Kara Hurst leads the development and evolution of sustainability and social responsibility at Amazon.

A scientist and entrepreneur, Gabriel Kra invests in solar energy, hydrogen, plant-based food, storage and other climate technologies.

Jorge Mañes Rubio creates artworks that rethink humanity's relationship with the universe and all the beings that live in it -- whether human, nonhuman, material or spiritual.

Wanjira Mathai has more than 20 years of experience advocating for social and environmental change on both local and international platforms.

Vaitea Cowan wants to create a world where green hydrogen is readily available -- and fossil fuels are a thing of the past.

Jackson Browne has written and performed some of the most literate and moving songs in popular music -- and has defined a genre of songwriting charged with honesty, emotion and personal politics.

Andras Forgacs produces animal products -- meat and leather -- without the animal.

Marco Alverà is an Italian/American businessman and CEO of Snam, Europe’s largest natural gas utility.

Architect William McDonough believes green design can prevent environmental disaster and drive economic growth. He champions “cradle to cradle” design, which considers a product's full life cycle -- from creation with sustainable materials to a recycled afterlife.

Eben Bayer is co-inventor of MycoBond, an organic (really -- it's based on mycelium, a living, growing organism) adhesive that turns agriwaste into a foam-like material for packaging and insulation.

Matthew Mazzotta uses clouds, giant flamingos, houses and dog waste to design unique public spaces with communities to solve unaddressed issues.

Tasso Azevedo has helped reduce the rate of deforestation in Brazil’s Amazon rainforest by 75 percent — and inspired similar efforts around the world.

Activist Patrisse Cullors created the hashtag #BlackLivesMatter as a tonic against years of injustice by police forces and prisons.

Physicist Brian Cox has two jobs: working with the Large Hadron Collider at CERN, and explaining big science to the general public. He's a professor at the University of Manchester.

Allan Adams is a theoretical physicist working at the intersection of fluid dynamics, quantum field theory and string theory.

A Louisiana native, Colette Pichon Battle fights to advance human rights for communities on the frontline of the struggle against climate change.

Andrew "Twiggy" Forrest is an Australian businessman, philanthropist and entrepreneur, widely considered one of the country’s greatest change agents.

Angela Francis finds ways to work on changing our human systems -- energy, production, consumption, transport and planning -- to bring them in line with our environment.

At 14, Taylor Wilson became the youngest person to achieve fusion -- with a reactor born in his garage. Now he wants to save our seaports from nuclear terror.

Jessica Green wants people to understand the important role microbes play in every facet of our lives: climate change, building ecosystems, human health, even roller derby -- using nontraditional tools like art, animation and film to help people visualize the invisible world.

Lisa Jackson is an environmental and social impact leader who has dedicated her career to building a greener and more just economy.

TED Fellow Federica Bianco is a cross-disciplinary scientist who can't stay still.