Swiss pilot Bertrand Piccard prepares for a test flight of the solar-powered Solar Impulse 2 experimental aircraft in Payerne November 13, 2014. The aircraft, weighing 2.4 tons with a wingspan of 72 meters, is fitted with more than 17,000 solar cells. An attempt to fly around the world in stages using only solar energy will be made in 2015. (Photo by Ruben Sprich/Reuters)

An employee of the National Park Service takes a selfie with President Barack Obama, left, in the background meeting with the crowd after a tour of Everglades National Park on Earth Day, Wednesday, April 22, 2015, in Florida. Obama used the visit to warn of the damage that climate change is already inflicting on the nation's environmental treasures. (Photo by Lynne Sladky/AP Photo)

A handout photograph provided by Brian Kubicki of Costa Rican Amphibian Research Center on 26 April 2016 shows a “Crystal frog”, Hyalinobatrachium dianae (H. diane). This frog was discovered by US biologist Brian Kubicki and Costa Ricans Stanley Salazar and Robert Puschendorf in a rainy forest of Costa Rican caribbean after 40 years without notice of any new example of this kind. (Photo by Brian Kubicki/EPA/Costa Rican Amphibian Research Center)

Self-titled Pricasso – real name Tim Patch, 71, – is using his very own pen*s to create his masterpiece – and claims to have made close to £500k from his saucy paintings. Here: Pricasso gets to work with his tools - and paints The Sun's newspaper correspondent Amy Nickell with his bits in London, England on November 5, 2019. (Photo by Stewart Williams/The Sun)

A woman wearing a face mask as a precaution against the COVID-19 while using smartphone in a subway train in Hong Kong, Thursday, February 27, 2020. As the worst-hit areas of Asia continued to struggle with a viral epidemic, with hundreds more cases reported Thursday in South Korea and China, worries about infection and containment spread across the globe. (Photo by Kin Cheung/AP Photo)

WWII veterans attend a ceremony to place tobacco pouches of soil from WWII mass graves of Red Army soldiers abroad, in the custody of the Central Armed Forces Museum in Moscow, Russia on March 6, 2020. The grave soil has been brought from Abkhazia, Germany, Kyrgyzstan, US, Ukraine, France, Estonia, Mongolia, Bulgaria, UK, Uzbekistan and South Ossetia. (Photo by Alexander Shcherbak/TASS)

In this photo released by the Alaska National Guard, Alaska Army National Guard soldiers use a CH-47 Chinook helicopter to removed an abandoned bus, popularized by the book and movie “Into the Wild”, out of its location in the Alaska backcountry Thursday, June 18, 2020, as part of a training mission. Alaska Natural Resources Commissioner Corri Feige, in a release, said the bus will be kept in a secure location while her department weighs various options for what to do with it. (Photo by Sgt. Seth LaCount/Alaska National Guard via AP Photo)

A young woman looks at her smartphone sitting in front of a mannequin use to keep social distancing at a Chinese cuisine restaurant in Tokyo, Japan, 27 July 2020. Japan's total number of COVID-19 cases crossed the 30,000 line showing the new coronavirus pandemic is spreading across the country and not only in Tokyo and Osaka megalopolis. (Photo by Franck Robichon/EPA/EFE)