A tourist visits the Oktyabrskaya cave of the Bogdanovich glacier located in the Tian Shan mountain range near Almaty, Kazakhstan February 20, 2021. Picture taken February 20, 2021. REUTERS/Pavel Mikheyev TPX IMAGES OF THE DAY

Tourists visit the Oktyabrskaya cave of the Bogdanovich glacier located in the Tian Shan mountain range near Almaty, Kazakhstan February 20, 2021. Picture taken February 20, 2021. REUTERS/Pavel Mikheyev

A tourist visits the Oktyabrskaya cave of the Bogdanovich glacier located in the Tian Shan mountain range near Almaty, Kazakhstan February 20, 2021. Picture taken February 20, 2021. REUTERS/Pavel Mikheyev

A tourist visits the Oktyabrskaya cave of the Bogdanovich glacier located in the Tian Shan mountain range near Almaty, Kazakhstan February 20, 2021. Picture taken February 20, 2021. REUTERS/Pavel Mikheyev

A tourist visits the Oktyabrskaya cave of the Bogdanovich glacier located in the Tian Shan mountain range near Almaty, Kazakhstan February 20, 2021. Picture taken February 20, 2021. REUTERS/Pavel Mikheyev

A Palestinian woman prepares bread for baking in a hillside cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

A Palestinian woman washes utensils outside a hillside cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

A Palestinian woman prepares food in a hillside cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

A Palestinian woman walks towards a cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

A Palestinian woman washes utensils outside a hillside cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

Palestinian man Barakat Mour sits in a hillside cave with his brother amid Palestinian worries about Israeli settler incursions into the property, in Masafer Yatta near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

A Palestinian woman enters a hillside cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

Members of the Palestinian family Mour sleep in a hillside cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

Palestinian children use a mobile phone inside their family's hillside cave amid Palestinian worries about Israeli settler incursions into the property, near Hebron, in the Israeli-occupied West Bank, January 28, 2021. Picture taken January 28, 2021. REUTERS/Mussa Qawasma

Alexa Cave sits during the viewing of her brother Dustin Higgs, the 13th and final prisoner executed by former U.S. President Donald Trump’s administration, with family members at the Darrow Joseph funeral home in Poughkeepsie, New York, U.S., January 29, 2021. REUTERS/Shannon Stapleton

Alexa Cave grieves for her brother Dustin Higgs, the 13th and final prisoner executed by former U.S. President Donald Trump’s administration, with family members at his graveside in Poughkeepsie, New York, U.S., January 29, 2021. REUTERS/Shannon Stapleton

Alexa Cave grieves for her brother Dustin Higgs, the 13th and final prisoner executed by former U.S. President Donald Trump’s administration, with family members leaving his graveside in Poughkeepsie, New York, U.S., January 29, 2021. REUTERS/Shannon Stapleton

Workers wearing protective suits bury a victim of the coronavirus disease (COVID-19) at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

Workers wearing protective suits bury a victim of the coronavirus disease (COVID-19) at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

Workers wearing protective suits bury a victim of the coronavirus disease (COVID-19) at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

Workers wearing protective suits disinfect themselves after burying a victim of the coronavirus disease (COVID-19) at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

Family members of a victim of the coronavirus disease (COVID-19) pray during a burial at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

A family member of a victim of the coronavirus disease (COVID-19) prays after a burial at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

Workers wearing protective suits bury a victim of the coronavirus disease (COVID-19) at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

Workers wearing personal protective equipment (PPE) carry the body of a victim of the coronavirus disease (COVID-19) at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

A worker rests beside a coffin of a victim of the coronavirus disease (COVID-19) before a burial at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

A family member of a victim of the coronavirus disease (COVID-19) reacts during a burial at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

A family member of a victim of the coronavirus disease (COVID-19) reads a book beside a grave at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng

Family members of a victim of the coronavirus disease (COVID-19) cry after a burial at a cemetery, in Batu Caves, Malaysia January 27, 2021. REUTERS/Lim Huey Teng TPX IMAGES OF THE DAY

Alexa Cave, sister of Dustin Higgs, talks about the moment she watched her brother being executed at the Federal Correctional Complex in Terre Haute, Indiana, U.S. January 16, 2021. REUTERS/Bryan Woolston

Alexa Cave, sister of Dustin Higgs, talks about her recent experiences visiting her brother in Terre Haute, Indiana, U.S. January 15, 2021. Picture taken January 15, 2021. REUTERS/Bryan Woolston

People observe icicles formed on Gibsons Cave and Summerhill Force Waterfall are pictured in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

Icicles formed on Gibsons Cave and Summerhill Force Waterfall are pictured in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

Icicles formed on Gibsons Cave and Summerhill Force Waterfall are pictured in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

Icicles formed next to Gibsons Cave and Summerhill Force Waterfall are pictured in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

Icicles formed on Gibsons Cave and Summerhill Force Waterfall are pictured in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

Icicles formed on Gibsons Cave and Summerhill Force Waterfall are pictured in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

A photographer takes pictures of icicles formed on Gibsons Cave and Summerhill Force Waterfall in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

A photographer takes pictures of icicles formed on Gibsons Cave and Summerhill Force Waterfall in Newbiggin, Barnard Castle, Britain, January 10, 2021. REUTERS/Lee Smith

A member of the Slovenian Cave Rescue Association dressed as Santa Clause rappels down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

Members of the Slovenian Cave Rescue Association dressed as Santa Clauses pose after rappelling down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

Members of the Slovenian Cave Rescue Association dressed as Santa Clauses rappel down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

A member of the Slovenian Cave Rescue Association dressed as Santa Clause waves after rappelling down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

Members of the Slovenian Cave Rescue Association dressed as Santa Clauses rappel down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

A member of the Slovenian Cave Rescue Association dressed as Santa Clause rappels down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

Members of the Slovenian Cave Rescue Association dressed as Santa Clauses rappel down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

A member of the Slovenian Cave Rescue Association dressed as Santa Clause rappels down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

Members of the Slovenian Cave Rescue Association dressed as Santa Clauses rappel down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

A member of the Slovenian Cave Rescue Association dressed as Santa Clause rappels down the glass facade of a paediatric hospital in Ljubljana, Slovenia, December 21, 2020. REUTERS/Borut Zivulovic

Tanya Harley, the owner of All Tressed Up Hair Salon, wears a face shield as she treats her customer Zada Cave in Lamesa, Texas, U.S., December 18, 2020. REUTERS/Go Nakamura

Helen Tromp takes a picture at the entrance of the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

People stand in the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse TPX IMAGES OF THE DAY

People stand in the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

People stand in the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

A photographer takes a picture in the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

A photographer takes a picture in the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

A sign is pictured at the entrance of the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

Felicien Rey-Bellet of Glacier 3000 stands at the entrance of the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

Hoarfrost is pictured at the entrance of the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse

Hoarfrost is pictured at the entrance of the "Mill", a 20m long natural ice cave created by melted water accumulated during the summer and by a siphon effect leaves in the autumn giving way to an ice cathedral, at the Glacier 3000 ski resort in Les Diablerets, Switzerland, December 10, 2020. REUTERS/Denis Balibouse