An ozone hole five times the size of California opened over the Arctic this spring, matching ozone loss over Antarctica for the first time on record, scientists said on Sunday.
Formed by a deep chill over the North Pole, the unprecedented hole at one point shifted over eastern Europe, Russia and Mongolia, exposing populations to higher, but unsustained, levels of ultraviolet light.
Ozone, a molecule of oxygen, forms in the stratosphere, filtering out ultraviolet rays that damage vegetation and can cause skin cancer and cataracts.
The shield comes under seasonal attack in both polar regions in the local winter-to-spring.
Part of the source comes from manmade chlorine-based compounds, once widely used in refrigerants and consumer aerosols, that are being phased out under the UN’s Montreal Protocol.
However, the loss itself is driven by deep cold, which causes water vapor and molecules of nitric acid to condense into clouds in the lower stratosphere.
These clouds in turn become a “bed” where atmospheric chlorine molecules convert into reactive compounds that gobble up ozone.
Ozone loss over the Antarctic is traditionally much bigger than over the Arctic because of the far colder temperatures there.
In the Arctic, records have — until now — suggested that the loss, while variable, is far more limited.
Satellite measurements conducted in the Arctic winter-to-spring from last year until this year found ozone badly depleted at a height of between 15km and 23km.
The biggest loss — of more than 80 percent — occurred between 18km and 20km.
“For the first time, sufficient loss occurred to be reasonably described as an Arctic ozone hole,” says the study, appearing in the British science journal Nature.
The trigger was the polar vortex, a large-scale cyclone that forms every winter in the Arctic stratosphere, but which last winter was born in extremely cold conditions, Gloria Manney, of the Jet Propulsion Laboratory in California, said in an e-mail.
“Especially low total column ozone values [below 250 Dobson Units] were observed for about 27 days in March and early April,” Manney said. “The maximum area with values below 250 Dobson Units was about 2 million km2, roughly five times the area of Germany or California.”
This was similar in size to ozone loss in Antarctica in the mid-1980s.
In April, the vortex shifted over more densely populated parts of Russia, Mongolia and eastern Europe for about two weeks.
Measurements on the ground showed “unusually high values” of ultraviolet, although human exposure was not constant as the vortex shifted location daily before eventually fading, Manney said.
The study challenges conventional thinking about the Arctic’s susceptibility to ozone holes. This thinking is based on only a few decades of satellite observations.
SCHEDULE: The delegation is due to meet with President Tsai Ing-wen this morning and witness the signing of an MOU on bilateral health cooperation in the afternoon US Secretary of Health and Human Services (HHS) Alex Azar yesterday arrived in Taipei aboard a US government plane at the head of a delegation that is the highest-level visit by a US official since Washington switched diplomatic recognition to China in 1979. Azar’s flight landed at Taipei International Airport (Songshan airport) at 4:48pm, nearly one hour earlier than scheduled, the Ministry of Foreign Affairs said. The apron where it landed is reserved for military aircraft, the Songshan Air Force Base Command said. The members of Azar’s delegation included HHS Assistant Secretary for Preparedness and Response Robert Kadlec, HHS Chief of Staff Brian
ALEX AZAR: The first visit by a head of the Department of Health and Human Services would strictly observe the CECC’s special regulations, the Ministry of Foreign Affairs said US Secretary of Health and Human Services (HHS) Alex Azar is to lead a delegation to Taiwan — the highest-level visit by a US Cabinet official since the two sides cut formal relations in 1979. The plan was announced yesterday morning by the US Department of Health and Human Services and confirmed by the Ministry of Foreign Affairs (MOFA). Beijing has expressed its concerns to Washington, Chinese Ministry of Foreign Affairs spokesman Wang Wenbin (汪文斌) said later yesterday. Taiwan and the US only issued statements saying that the visit would happen “in the coming days.” MOFA said that due to security concerns, it would
‘CROSS-STRAIT CONSIDERATIONS’: Groups said that the Ministry of Education’s policies excluded Chinese and students should not be blocked over political issues The Taiwan International Student Movement yesterday said it would protest today outside the Ministry of Education in Taipei against a policy that excludes some Chinese students from returning to Taiwan amid the COVID-19 pandemic. Since June 17, the ministry has allowed foreign students from 19 “low risk” and “medium-low risk” countries and regions to enter Taiwan. On July 22, it announced that it was relaxing restrictions to include students from all countries and regions who are graduating this semester and on Wednesday it further expanded entry to students enrolled in degree programs. A letter sent by the ministry on Wednesday to universities did
The military last week sent “no small number” of Marine Corps officers to the Pratas Islands (Dongsha Island, 東沙群島) following reports of a Chinese People’s Liberation Army (PLA) drill targeting the islands scheduled for this month. In an interview with Hong Kong’s Bauhinia Magazine published on Saturday last week, PLA National Defense University professor Li Daguang (李大光) confirmed that the Chinese army was planning to stage a simulated invasion of the Pratas Islands in the South China Sea this month. The islands comprise three atolls, with Pratas Island, at 1.74km2, being the largest. They lie southwest of Taiwan proper in the South