Whether it's dandelions blooming in your backyard or purslane sprouting from the sidewalk, vegan forager Alexis Nikole Nelson is on a mission to show how freely growing flora could make its way to your plate. With contagious enthusiasm and a live cooking demo, she explains the benefits of expanding your palate to include "wild" foods that are delicious, nutritious and planet-friendly -- and gives three tips for helping others go from skeptical to confident in their own food adventures.

Even with public trust at an all-time low, Wikipedia continues to maintain people's confidence. How do they do it? Former CEO of Wikimedia Foundation Katherine Maher delves into the transparent, adaptable and community-building ways the online encyclopedia brings free and reliable information to the public -- while also accounting for bias and difference of opinion. "The seeds of our disagreement can actually become the roots of our common purpose," she says.

Air travel opens our eyes to the world, but it also comes at a high cost to the environment. Piloting us into a future of green aviation, innovator Ryah Whalen shares three ways to lower the industry's carbon footprint through smarter designs, eco-friendly fuel and new technology -- so we can continue to explore the planet without hurting it.

"If we can unlock the full potential of our cities, we can minimize the price the planet pays for hosting us in our growing numbers," says Marvin Rees, the Mayor of Bristol, UK, who understands deeply how cities can help (or hurt) the environment. Rees notes that while sustainable infrastructure already exists in many parts of the world -- like electric buses in Colombia and freshwater reserves in Singapore -- major investments could make similar innovations more far-reaching and successful. He highlights the pivotal role of city mayors in advocating for a "worldwide network of efficient decarbonized cities" that will bring the world closer to its climate goals.

Linking together the histories of Henrietta Swan Leavitt, Edwin Hubble and Tracy K. Smith, poet and thinker Maria Popova crafts an astonishing story of how humanity came to see the edge of the observable universe. (Followed by an animated excerpt of "My God, It's Full of Stars," by Tracy K. Smith)

The weekend. Social Security. Health insurance. What do these things have in common? They all exist thanks to the advocacy of labor unions. Political economist Margaret Levi explains how these organizations forge equality and protect worker rights, calling for a 21st-century revival of the labor movement in order to build a more equitable future.

In a talk packed with wry wisdom, pop culture queen Bevy Smith shares hard-earned lessons about authenticity, confidence, mature success and why, if you put in the work, "life gets greater later."

Lighting up the TED stage, Nobel laureate Al Gore takes stock of the current state of climate progress and calls attention to institutions that have failed to honor their promises by continuing to pour money into polluting sectors. He explains how the financial interests of fossil fuel companies have blocked the policymaking process in key countries -- and calls for a global epiphany to take on the climate crisis. "Do not give up hope," Gore says. "And remember always that political will is itself a renewable resource."

In times of uncertainty, leaders have a responsibility to inspire hope. Sharing hard-won wisdom, business leader Ken Chenault talks about what it takes to enact positive, enduring change -- and why it's more important than ever to invest in responsible innovation that uplifts people and centers equality and fairness.

Corporate inclusion visionary Deepa Purushothaman shares how women of color can advocate for themselves in workplace settings where they are undervalued, discriminated against and overlooked -- and how companies can foster working cultures that empower everyone to achieve success. (This conversation, hosted by TED current affairs curator Whitney Pennington Rodgers, was part of an exclusive TED Membership event. Visit ted.com/membership to become a TED Member.)