"This decade is a moment of choice unlike any we have ever lived," says Christiana Figueres, the architect of the historic 2015 Paris Agreement. The daughter of Costa Rica's beloved President José Figueres Ferrer, she shares how her father's unwillingness to lose the country he loved taught her how stubborn optimism can catalyze action and change. With an unshakeable determination to fight for the generations that will come after us, Figueres describes what stubborn optimism is (and isn't) -- and urges everyone to envision and work for the future they want for humanity.

Why has there been so little mention of saving Black lives from the climate emergency? For too long, racial justice efforts have been distinguished from climate justice work, says David Lammy, Member of Parliament for Tottenham, England. In a stirring talk about building a new movement to care for the planet, Lammy calls for inclusion and support of Black and minority leadership on climate issues and a global recognition that we can't solve climate change without racial, social and intergenerational justice.

"If we don't act now on climate change, this coming century may be one of humanity's last," says António Guterres, Secretary-General of the United Nations. As the world recovers from the COVID-19 pandemic, Guterres urges us to use this moment to rebuild with ambitious climate action in mind -- and lays out a blueprint for getting companies, governments and countries to reach net-zero carbon emissions by 2050. "We can only win the race to zero together," he says. "I urge you all to get on board."

A brief answer to one of the key questions about climate change: What is net zero? (Written by Myles Allen, David Biello and George Zaidan)

A brief answer to one of the key questions about climate change: Why is the world warming up? (Written by Myles Allen, David Biello and George Zaidan)

Cities pump out 70 percent of all global carbon emissions -- which means they also have the greatest opportunity to lower CO2 levels and energy consumption. Climate and data scientist Angel Hsu shares how cities around the world are leading the response to climate change by innovating new, low-carbon ways of living.

Cities pump out 70 percent of all global carbon emissions -- which means they also have the greatest opportunity to lower CO2 levels and energy consumption. Climate and data scientist Angel Hsu shares how cities around the world are leading the response to climate change by innovating new, low-carbon ways of living.

We could realistically see people starting to live and work on the Moon in the next decade -- and how we do it matters, says space policy researcher Jessy Kate Schingler. In this fascinating talk, she discusses the critical issues that arise when we consider civilization in outer space -- such as governance, property rights and resource management -- and shows how the Moon can be a template for solving our biggest challenges here on Earth.

Botanical artist Nirupa Rao captures the spirit and beauty of nature in watercolor. With a portfolio of enchanting, scientifically accurate illustrations, she aims to reignite our emotional connection to the environment -- and open our eyes to an entire kingdom hidden in plain sight.

Racism thrives on your silence and apathy, says human rights lawyer Dexter Dias. Telling the story of a harrowing UK court case that spotlights the corrosive effects of injustice, Dias urges us all to speak out and expose toxic myths about race -- in order to allow hope, change and justice to flourish.