Schoolchildren, students and activists attend a protest march to call for action against climate change, in Vienna, Austria, September 27, 2019. REUTERS/Leonhard Foeger

Demonstrators take part in a march as part of a world-wide protest called by "Fridays for Future" movement against climate change in Madrid, Spain, May 24, 2019. REUTERS/Susana Vera

A participant holds a replica depicting globe on fire during a "Fridays for Future" march calling for urgent measures to combat climate change, in Mumbai, India, September 27, 2019. REUTERS/Francis Mascarenhas

Activists take part in a pro-climate demonstration march in Lausanne, Switzerland September 27, 2019. REUTERS/Denis Balibouse

An activist takes part in a Global Climate Strike rally in Kolkata, India, September 20, 2019. REUTERS/Rupak De Chowdhuri TPX IMAGES OF THE DAY

Activists of "Ice on the rope" stand on blocks of ice under makeshift gallows as they take part in the Global Climate Strike of the movement Fridays for Future, in Munich, Germany, September 20, 2019. REUTERS/Michael Dalder

Schoolchildren, students and activists attend a protest march to call for action against climate change, in The Hague, Netherlands September 27, 2019. REUTERS/Piroschka van de Wouw

Sixteen year-old Swedish climate activist Greta Thunberg poses for a selfie with fellow activist Militza Flaco of Panama at the U.S. Supreme Court in Washington U.S., September 18, 2019. REUTERS/Kevin Lamarque

A child plays with a ball that represents an earth globe during the Global Climate Strike of the Fridays for Future movement in Sao Paulo, Brazil September 20, 2019. REUTERS/Nacho Doce ?

Swedish environmental activist Greta Thunberg watches as U.S. President Donald Trump enters the United Nations to speak with reporters in a still image from video taken in New York City, U.S. September 23, 2019. REUTERS/Andrew Hofstetter TPX IMAGES OF THE DAY

16-year-old Swedish Climate activist Greta Thunberg speaks at the 2019 United Nations Climate Action Summit at U.N. headquarters in New York City, New York, U.S., September 23, 2019. REUTERS/Carlo Allegri TPX IMAGES OF THE DAY

Swedish 16-year-old youth climate activist Greta Thunberg sits on the side amongst other youth climate activists at a news conference about the Green New Deal hosted by U.S. Senator Ed Markey (D-MA) on the Northeast lawn in front of the U.S. Capitol in Washington, U.S., September 17, 2019. REUTERS/Sarah Silbiger TPX IMAGES OF THE DAY

Sixteen year-old Swedish climate activist Greta Thunberg testifies at a House Foreign Affairs subcommittee and House Select Climate Crisis Committee joint hearing on "Voices Leading the Next Generation on the Global Climate Crisis" on Capitol Hill in Washington U.S., September 18, 2019. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY

European Commission President Jean-Claude Juncker kisses the hand of 16-year old Swedish environmental activist Greta Thunberg at a conference in Brussels, Belgium February 21, 2019. REUTERS/Yves Herman TPX IMAGES OF THE DAY

Canada's Prime Minister Justin Trudeau greets Swedish climate change teen activist Greta Thunberg before a climate strike march in Montreal, Quebec, Canada September 27, 2019. REUTERS/Andrej Ivanov

Swedish environmental activist Greta Thunberg cries at the end of her speech to the environment committee of the European Parliament in Strasbourg, April 16, 2019. REUTERS/Vincent Kessler

Swedish environmental activist Greta Thunberg, Ivy-Fleur Boileau, Virgile Mouquet, Adelaide Charlier and Alicia Arquetoux, French activists from the Youth for Climate movement, attend the questions to the government session at the National Assembly in Paris, France, July 23, 2019. REUTERS/Philippe Wojazer TPX IMAGES OF THE DAY

Swedish activist Greta Thunberg participates in a youth climate change protest in front of the United Nations Headquarters in Manhattan, New York City, New York, U.S., August 30, 2019. REUTERS/Jeenah Moon

Swedish environmental activist Greta Thunberg attends "Fridays for Future" protest, claiming for urgent measures to combat climate change, in Berlin, Germany, July 19, 2019. REUTERS/Fabrizio Bensch

Greta Thunberg, Swedish "Fridays for Future" climate activist, stands next to climbing equipment that hangs from an illegal tree house in the Hambach Forest that is supposed to be chopped away for the nearby open-cast brown coal mine of German utility RWE, west of Cologne, Germany, August 10, 2019. REUTERS/Wolfgang Rattay TPX IMAGES OF THE DAY

Climate change environmental teen activist Greta Thunberg takes part in a climate strike march in Montreal, Quebec, Canada September 27, 2019. REUTERS/Andrej Ivanov TPX IMAGES OF THE DAY

Sixteen year-old Swedish climate activist Greta Thunberg takes part in a demonstration as part of the Global Climate Strike in lower Manhattan in New York, U.S., September 20, 2019. REUTERS/Shannon Stapleton

Students listen to a speaker as they take part in a "Fridays for Future" protest claiming for urgent measures to combat climate change, in New Delhi, India, April 26, 2019. REUTERS/Anushree Fadnavis

Young climate activists attend a "Friday's for future" protest outside Germany's chancellery in Berlin, Germany, September 13, 2019. REUTERS/Fabrizio Bensch

Demonstrators take part in a "Fridays for Future" protest claiming for urgent measures to combat climate change in Berlin, Germany April 5, 2019. REUTERS/Michele Tantussi

Demonstrators take part in a "Fridays for Future" protest claiming for urgent measures to combat climate change, in Berlin, Germany, March 29, 2019. REUTERS/Fabrizio Bensch

French students take part in their sixth "Friday for Future" climate action protest in Paris, France, March 22, 2019. The banner reads: "We are not the utopians". REUTERS/Charles Platiau

Students perform under a shade made from used plastic bottles as they take part in a global protest against climate change in Gurugram, India, March 15, 2019. REUTERS/Adnan Abidi

A demonstrator holds a banner during a protest against climate change, organised by the YouthStrike4Climate movement, in Brighton, Britain March 15, 2019. REUTERS/Peter Nicholls

A student dress as a killer whale dances during a protest to demand global action on climate change as part of the "Fridays for Future" movement in Buenos Aires, Argentina. March 15, 2019. REUTERS/Agustin Marcarian

Belgian students claim for urgent measures to combat climate change during a demonstration in central Brussels, Belgium January 31, 2019. REUTERS/Yves Herman

People attend a "Fridays for Future" protest, claiming for urgent measures to combat climate change, at Stuttgart airport, Germany July 26, 2019. REUTERS/Andreas Gebert

Young people protest outside of the San Francisco Federal Building during the Global Climate Strike march in San Francisco, U.S. September 20, 2019. REUTERS/Kate Munsch TPX IMAGES OF THE DAY

Demonstrators take part in a protest against climate change called by the organization Fridays For Future ahead of the 2019 United Nations Climate Change Conference, also known as COP25, in Valparaiso, Chile, September 27, 2019. REUTERS/Rodrigo Garrido

School pupils protest to demand action, during the world march for climate change and the environment, called by the organization Fridays for Future inside of Secretary of State for the Environment in Sao Paulo, Brazil, May 24, 2019. REUTERS/Nacho Doce

Environmental activists hold signs as they take part in the Climate strike protest calling for action on climate change, in Nairobi, Kenya, September 20, 2019. REUTERS/Baz Ratner

Students take part in a "youth strike to act on climate change" demonstration in Paris, March 15, 2019. REUTERS/Gonzalo Fuentes

Members of "Fridays for Future" movement prepare placards for a world-wide protest called against climate change in Madrid, Spain, May 23, 2019. REUTERS/Sergio Perez

People gather in front of the Brandenburg Gate to take part in the Global Climate Strike of the movement Fridays for Future, in Berlin, Germany, September 20, 2019. REUTERS/Fabrizio Bensch

Students hold placards as they take part in the Fridays for Future climate change action protest in Paris, France, September 20, 2019. REUTERS/Charles Platiau

Students take part in the Global Climate Strike of the Fridays for Future movement in Berlin, Germany, September 20, 2019. REUTERS/Christian Mang

A giant "carbon clock", installed by young activists from the "Fridays for Future" campaign, displays how much carbon dioxide can be released into the atmosphere to limit global warming to a maximum of 1.5 or 2 degrees Celsius, at former gasometer, ahead a worldwide climate strike over the weekend, in Berlin, Germany September 18, 2019. REUTERS/Hannibal Hanschke

People march in the climate strike march in Montreal, Quebec, Canada September 27, 2019. REUTERS/Andrej Ivanov

People attend a "Fridays for Future" protest, claiming for urgent measures to combat climate change, in Berlin, Germany, July 19, 2019. REUTERS/Fabrizio Bensch

Students take part in a "youth strike to act on climate change" demonstration in Paris, France, March 15, 2019. REUTERS/Gonzalo Fuentes

A student holds a placard that reads "which green are you looking?" during a protest to demand global action on climate change as part of the "Fridays for Future" movement in Buenos Aires, Argentina. March 15, 2019. REUTERS/Agustin Marcarian

Students take part in a protest claiming for urgent measures to combat climate change, in Hamburg, Germany, March 1, 2019. REUTERS/Morris Mac Matzen

Belgian student claims for urgent measures to combat climate change during a demonstration in central Brussels, Belgium February 21, 2019. REUTERS/Yves Herman

Anuna De Wever reacts as Belgian students claim for urgent measures to combat climate change during a demonstration in central Brussels, Belgium January 31, 2019. REUTERS/Yves Herman

A participant holds a dog with a placard during a protest march to call for action against climate change, in The Hague, Netherlands September 27, 2019. REUTERS/Piroschka van de Wouw TPX IMAGES OF THE DAY

Demonstrators lie on the ground at the end of a march as part of a world-wide protest called by "Fridays for Future" movement against climate change in Madrid, Spain, May 24, 2019. REUTERS/Susana Vera

Students take part in a protest demanding action on climate change, near the Colosseum, in Rome, Italy March 15, 2019. REUTERS/Remo Casilli