Showing posts with label Artic Melting. Show all posts
Showing posts with label Artic Melting. Show all posts

Saturday, March 29, 2025

Global Sea Ice Hits a New Low. The data comes after researchers reported that the past 10 years have been the 10 hottest on record.

 

Ice floes off Nuuk, Greenland, this month.Credit...Odd Andersen/Agence France-Presse — Getty Images
 
 



 



Earth is missing a lot of sea ice this year. Enough to cover the entire United States east of the Mississippi.

That was announced by researchers at NASA and the National Snow and Ice Data Center on Thursday, who said the amount of sea ice on the planet had reached the lowest level ever recorded in March.

The record comes days after the World Meteorological Organization reported that the past 10 years have been the 10 hottest on record, with 2024 the hottest year. The global rise in temperatures is tied to increasing concentrations of greenhouse gases, largely caused by the burning of fossil fuels.

“Warming temperatures drive melting ice across the globe, and because we’re seeing such high temperatures, it’s not surprising that this year we’re seeing the least amount of ice coverage,” said Linette Boisvert, an ice scientist at NASA’s Goddard Space Flight Center.

 

The center has been compiling data for almost 50 years, primarily through a Department of Defense satellite program. The global sea ice extent includes measurements taken in both the Southern Hemisphere and the Northern Hemisphere, which experience opposite seasons.

Dr. Boisvert compared the freezing and melting of sea ice between winter and summer to the heartbeat of the planet. The pulses between the winter maximum and summer minimum used to be shorter. But with more sea ice melting away, the distance between pulses has grown larger.

“It’s like the heartbeat of the planet is slowing down,” Dr. Boisvert said. “It’s not good.”

 

Sea ice plays many important roles for the global climate: Its white surface can reflect energy back into space, helping the planet cool. It also acts like a blanket for the ocean, insulating it and preventing ocean heat from reaching the atmosphere. Less sea ice means more heat goes in Earth’s systems, warming the atmosphere and the oceans.

The extent of sea ice isn’t the only measurement scientists are tracking. The thickness of the ice also matters and, since the 1980s, Arctic sea ice has become thinner.

 

While thicker sea ice tends to survive the summer melt, nowadays most of the sea ice completely melts during the summer, preventing it from thickening year after year. More open ocean means more dark surfaces to absorb more heat from the sun, which in turn melts more ice. The melting becomes its own positive feedback loop.

Changes in remote polar regions affect the rest of the globe, including changes to ocean currents and weather patterns.

“It’s really important to have scientists’ eyes on the data,” Dr. Boisvert said. “It would be really detrimental not to have funding for this type of work.”

Melting sea ice also has negative implications for marine life, tourism in polar regions and global shipping. It’s important for military activities, Indigenous communities in Alaska and the fishing industry, according to Walt Meier, a senior research scientist at the National Snow and Ice Data Center, a research organization at the University of Colorado, Boulder. The trend of decreasing sea ice in the Arctic is an increasingly clear indicator of global warming, he said.

“We’re seeing something that’s pretty unprecedented, at least on scales of human society for thousands of years,” Dr. Meier said.

 

Under the Trump administration, scientific agencies monitoring weather and climate data have been under threat. In March, NASA fired its chief scientist and eliminated more than a dozen other senior positions. The National Oceanic and Atmospheric Administration, which collects global climate data, fired hundreds of probationary employees in February and officials said officials they had plans to shrink its work force by nearly 20 percent. Projects focused on polar regions lost managers who oversee research when the National Science Foundation laid off about a tenth of its work force.

When asked about the cuts, Dr. Meier noted that groups in Europe and Japan also monitor global sea ice.

“It’s not like there’s not going to be any knowledge of what’s going on in the Arctic, regardless of what happens in the U.S.,” he said

“But I, and I think all of us here at N.S.I.D.C., are focused on the data and our research and doing our best to serve the public by keeping people informed on what’s happening in the polar regions.”


 

Monday, November 11, 2024

Por que o nível do mar está subindo cada vez mais rápido? Aumento vem causando o desaparecimento de praias e a destruição de casas principalmente durante tempestades

 

Água invade a faixa de areia na Praia de Copacabana, no Rio; nível do mar está subindo cada vez mais rápido. Foto: PEDRO KIRILOS/ESTADÃO - 14/06/2023

 Por Fernando Reinach

 Em 2024 comemoramos 30 anos em que altímetros instalados em satélites medem continuamente o nível dos oceanos ao redor do planeta. Uma análise cuidadosa dos dados coletados nessas três décadas mostra que o nível do oceano está subindo e que o ritmo do aumento dobrou nos últimos anos.

 

Qualquer pessoa olhando o mar pode imaginar quão difícil é medir seu nível. A cada segundo, ondas sobem e descem, a cada dia as marés sobem e descem e os grandes sistemas climáticos cíclicos como o El Niño provocam mudanças que duram anos. Além disso, a água dilata e contrai com mudanças da temperatura dos oceanos. Tudo isso combinado torna uma tarefa hercúlea medir o aumento do nível médio do mar com uma precisão de milímetros.

PUBLICIDADE

Foi somente com a colocação de altímetros precisos em satélites 30 anos atrás, capazes de medir a distância entre a superfície do oceano e o satélite, que isso se tornou possível. A cada segundo a distância de milhares de pontos em todos os oceanos e o satélite são determinadas. E, depois de corrigir para todas as flutuações, os computadores calculam o nível médio global do oceano.

O gráfico obtido ao longo dos 30 anos e as projeções para o futuro podem ser vistos na figura abaixo.


 Nesses últimos 30 anos, o nível do mar subiu 111 milímetros, subindo em média 3,5 milímetros por ano. Esse é um número pequeno, mas o preocupante é que a velocidade da subida vem aumentando. No início do período de 30 anos, em 1993, o mar subia 2,5 milímetros por ano, mas em 2023 ele subiu 4,5 milímetros em um ano. Extrapolando esse aumento até o ano de 2050, é provável que o nível do mar subirá mais 169 milímetros.


 

Esse aumento se deve principalmente ao derretimento das geleiras e a dilatação da água devido ao aquecimento da atmosfera e a transferência desse calor para os oceanos. Esse número é relativamente pequeno, mas, por não ser distribuído igualmente ao longo das costas de todos os continentes, vem causando o desaparecimento de praias e a destruição de casas principalmente durante tempestades.

 

Nas próximas décadas não vai ser o aumento do nível do mar que vai afetar a vida das cidades costeiras, mas o aumento da intensidade das tempestades causadas pelo aumento da temperatura. A importância desse resultado é que ele confirma uma das premissas mais importantes dos modelos climáticos: a velocidade da subida do nível dos oceanos. As outras duas medidas globais são a temperatura média da atmosfera e o nível de gás carbônico na atmosfera.

Essas medidas experimentais são extremamente importantes pois são elas que ancoram os modelos preditivos do IPCC.

Mais informações: The rate of global sea level rise doubled during the past three decades. Communications Earth & Environmental. https://doi.org/10.1038/s43247-024-01761-5 2024

  

Tuesday, June 25, 2024

Newly identified tipping point for ice sheets could mean greater sea level rise

 

A satellite image of ice-pack breakup at the mouth of the Pine Island glacier in Antarctica. Photograph: Planet Observer/Universal Images Group/Getty Images

 Small increase in temperature of intruding water could lead to very big increase in loss of ice, scientists say

 

A newly identified tipping point for the loss of ice sheets in Antarctica and elsewhere could mean future sea level rise is significantly higher than current projections.

A new study has examined how warming seawater intrudes between coastal ice sheets and the ground they rest on. The warm water melts cavities in the ice, allowing more water to flow in, expanding the cavities further in a feedback loop. This water then lubricates the collapse of ice into the ocean, pushing up sea levels.

The researchers used computer models to show that a “very small increase” in the temperature of the intruding water could lead to a “very big increase” in the loss of ice – ie, tipping point behaviour.

It is unknown how close the tipping point is, or whether it has even been crossed already. But the researchers said it could be triggered by temperature rises of just tenths of a degree, and very likely by the rises expected in the coming decades.


Sea level rise is the greatest long-term impact of the climate crisis and is set to redraw the world map in coming centuries. It has the potential to put scores of major cities, from New York City to Shanghai, below sea level and to affect billions of people.

The study addresses a key question of why current models underestimate the sea level seen in earlier periods between ice ages. Scientists think some ice sheet melting processes must not yet included in the models.

“[Seawater intrusion] could basically be the missing piece,” said Dr Alexander Bradley of the British Antarctic Survey, who led the research. “We don’t really have many other good ideas. And there’s a lot of evidence that when you do include it, the amount of sea level rise the models predict could be much, much higher.”

Previous research has shown that seawater intrusion could double the rate of ice loss from some Antarctic ice shelves. There is also real-world evidence that seawater intrusion is causing melting today, including satellite data that shows drops in the height of ice sheets near grounding zones.

“With every tenth of a degree of ocean warming, we get closer and closer to passing this tipping point, and each tenth of a degree is linked to the amount of climate change that takes place,” Bradley said. “So we need very dramatic action to restrict the amount of warming that takes place and prevent this tipping point from being passed.”

The most important action is to cut the burning of fossil fuels to net zero by 2050.

Bradley said: “Now we want to put [seawater intrusion] into ice sheet models and see whether that two-times sea level rise plays out when you analyse the whole of Antarctica.”

Scientists warned in 2022 that the climate crisis had driven the world to the brink of multiple “disastrous” tipping points, including the collapse of Greenland’s ice cap and the collapse of a key current in the north Atlantic, disrupting rains upon which billions of people depend for food.

 

Research in 2023 found that accelerated ice melting in west Antarctica was inevitable for the rest of the century, no matter how much carbon emissions are cut, with “dire” implications for sea levels.

The new research, published in the journal Nature Geoscience, found that some Antarctic ice sheets were more vulnerable to seawater intrusion than others. The Pine Island glacier, currently Antarctica’s largest contributor to sea level rise, is especially vulnerable, as the base of the glacier slopes down inland, meaning gravity helps the seawater penetrate. The large Larsen ice sheet is similarly at risk.

The so-called “Doomsday” glacier, Thwaites, was found to be among the least vulnerable to seawater intrusion. This is because the ice is flowing into the sea so fast already that any cavities in the ice melted by seawater intrusion are quickly filled with new ice.

Dr Tiago Segabinazzi Dotto, of the UK’s National Oceanography Centre, welcomed the new analysis of the ocean-ice feedback loop under ice sheets.

“The researchers’ simplified model is useful for showing this feedback, but a more realistic model is highly needed to evaluate both positive and negative feedbacks,” he said. “An enhancement of observations at the grounding zone is also essential to better understand the key processes associated with the instability of ice shelves.”


 

Sunday, May 12, 2024

(Artic Melting) - Afghanistan flash floods kill more than 300 as torrents of water and mud crash through villages - theguardian.com

 

 Afghan men shovel mud from a house following flash floods after heavy rains at a village in the Baghlan-e-Markazi district of northern Afghanistan’s Baghlan province on Saturday. Photograph: Atif Aryan/AFP/Getty Images

More than 300 people were killed in flash floods that ripped through multiple provinces in Afghanistan, the UN’s World Food Programme said, as authorities declared a state of emergency and rushed to rescue the injured.

Many people remained missing after heavy rains on Friday sent roaring rivers of water and mud crashing through villages and across agricultural land in several provinces, causing what one aid group described as a “major humanitarian emergency”.

Survivors picked through muddy, debris-littered streets and damaged buildings on Saturday as authorities and non-governmental groups deployed rescue workers and aid, warning that some areas had been cut off by the flooding.

 

Northern Baghlan province was one of the hardest hit, with more than 300 people killed there alone, and thousands of houses destroyed or damaged, according to the World Food Programme.

“On current information: in Baghlan province there are 311 fatalities, 2,011 houses destroyed and 2,800 houses damaged,” said Rana Deraz, a communications officer for the UN agency in Afghanistan.

There were disparities between the death tolls provided by the government and humanitarian agencies.

The UN’s International Organisation for Migration said on Saturday that there were 218 deaths in Baghlan. Abdul Mateen Qani, spokesman for the interior ministry, told Agence France-Presse that 131 people had been killed in Baghlan, but that the government toll could rise.

“Many people are still missing,” he said.

Another 20 people were reported dead in northern Takhar province and two in neighbouring Badakhshan, he added.

 Taliban government spokesman Zabihullah Mujahid said on Twitter/X: “Hundreds of our fellow citizens have succumbed to these calamitous floods.”

 He added: “The deluge has wrought extensive devastation upon residential properties, resulting in significant financial losses.”

 

Torrential rains caused heavy damage in Baghlan, Takhar and Badakhshan, as well as western Ghor and Herat provinces, officials said, in a country racked by poverty and heavily dependent on agriculture.

“My house and my whole life was swept away by the flood,” said Jan Mohammad Din Mohammad, a resident of the Baghlan provincial capital, Pul-e-Khumri.

His family had managed to flee to higher ground but when the weather cleared and they returned home, “there was nothing left, all my belongings and my house had been destroyed”, he said.

“I don’t know where to take my family … I don’t know what to do.”

Emergency personnel were rushing to rescue injured and stranded Afghans. The air force said it had started evacuation operations as skies cleared on Saturday, adding that more than 100 injured people had been transferred to hospital.

“By announcing the state of emergency in [affected] areas, the ministry of national defence has started distributing food, medicine and first aid to the impacted people,” it said.

A vehicle laden with food and water was seen in Baghlan’s Baghlan-i-Markazi district, as well as others carrying the dead to be buried.

  The bodies of Afghans killed in the floods are placed on the ground in Baghlan province, northern Afghanistan, on Saturday. Photograph: Mehrab Ibrahimi/AP

 

The UN secretary general, António Guterres, “expresses his solidarity with the people of Afghanistan [and] extends his condolences to the families of the victims”, said his spokesperson, Stephane Dujarric, adding that the UN was working with local authorities on providing assistance.

The International Rescue Committee (IRC) was also preparing a rapid response, adding that the floods should act as an “alarm bell” reminding world leaders and donors not to forget a country devastated by decades of conflict and beset by natural calamity.

“These latest floods have caused a major humanitarian emergency in Afghanistan, which is still reeling from a string of earthquakes” this year and severe flooding in March, IRC country director Salma Ben Aissa said.

Since mid-April, flash flooding and other floods had left about 100 people dead in 10 of Afghanistan’s provinces, authorities said.

Farmland has been swamped in a country where 80% of the more than 40 million people depend on agriculture to survive.

Afghanistan – which had a relatively dry winter, making it more difficult for the soil to absorb rainfall – is highly vulnerable to climate change.

The nation, ravaged by four decades of war, is one of the world’s poorest and, according to scientists, one of the worst prepared to face the consequences of global warming.

The UN special rapporteur for human rights in Afghanistan, Richard Bennett, said on Twitter/X that the floods were “a stark reminder of Afghanistan’s vulnerability to the climate crisis”.

“Both immediate aid and long term planning by the Taliban and international actors are needed.”

Summer 2025 was hottest on record in UK, says Met Office. Unprecedented average temperature made about 70 times more likely by human-induced climate change, says agency

The water levels at Broomhead reservoir in South Yorkshire have been low this summer. Photograph: Richard McCarthy/PA by   Damien Gayle The...