(C) Daily Kos
This story was originally published by Daily Kos and is unaltered.
. . . . . . . . . .



Atmospheric rivers are more often hitting the Arctic and melting its sea ice. [1]

['This Content Is Not Subject To Review Daily Kos Staff Prior To Publication.', 'Backgroundurl Avatar_Large', 'Nickname', 'Joined', 'Created_At', 'Story Count', 'N_Stories', 'Comment Count', 'N_Comments', 'Popular Tags']

Date: 2023-03-07

In 2003, fast attack submarine USS Connecticut (SSN-22) had partly surfaced in an ice pack when a polar bear began to lick and paw the exposed rudder to determine if it was worth eating. The bear eventually decided he was not in the mood for a sub and wandered off.

A recent study published in Nature Climate Change determined that the central Arctic and the Barents-Kara seas are experiencing anthropogenic-driven warming that is increasing the frequency of Atmospheric Rivers and driving the extreme sea early winter ice loss of over one-third of the Arctic Ocean.

The Arctic begins to refreeze in late fall and early winter; the maximum sea ice extent is in February.

NASA describes the sea ice life cycle like this:

When seawater begins to freeze, it forms tiny crystals just millimeters wide called frazil. How the crystals coalesce into larger masses of ice depends on whether the seas are calm or rough. In calm seas, the crystals form thin sheets of ice, nilas, so smooth that they have an oily or greasy appearance. These wafer-thin sheets of ice slide over each other and form rafts of thicker ice. In rough seas, ice crystals converge into slushy pancakes. These pancakes slide over each other to form smooth rafts, or they collide into each other, creating ridges on the surface and keels on the bottom.

NASA prepared the information page in 2016, seven years ago, and at the time, multi-year sea ice accounted for thirty-one percent. With our rising greenhouse gas emissions, we are heading toward a blue ocean event shortly where the multi-year ice melts in summer and is funneled into the Atlantic at the Nares Strait between the Canadian Archipelago and Greenland. The new ice in winter will be thinner and more vulnerable to climatic conditions.

Ice that survives the summer melt season may last for years. For ice to thicken, the ocean must lose heat to the atmosphere. But the ice also insulates the ocean like a blanket. Eventually, the ice gets so thick that no more heat can escape. Once the ice reaches this thickness—3 to 4 meters (10 to 13 feet)—further thickening isn’t possible except through collisions and ridge-building. Multiyear ice increasingly loses salt and hardens each year that it survives the summer melt. In contrast to multiyear ice, first-year ice is thinner, saltier, and more prone to melt in the subsequent summer. As of March 2015, multiyear ice accounted for 31 percent of the ice cover. The rest was first-year ice.

There is a process that will speed up the timetable for a blue ocean event: Atmospheric Rivers' arrival.

Pengfei Zhang, Assistant Research Professor of Atmospheric Science at Penn State, writes on the study in The Conversation:

Atmospheric rivers get their name because they are essentially long rivers of water vapor in the sky. They carry heat and water from the subtropical oceans into the midlatitudes and beyond. California and New Zealand both saw extreme rainfall from multiple atmospheric rivers in January 2023. These storms also drive the bulk of moisture reaching the Arctic. Warm air can hold more water vapor. So as the planet and the Arctic warm, atmospheric rivers and other storms carrying lots of moisture can become more common – including in colder regions like the Arctic. When atmospheric rivers cross over newly formed sea ice, their heat and rainfall can melt the thin, fragile ice cover away. Ice will start to regrow fairly quickly, but episodic atmospheric river penetrations can easily melt it again. The increasing frequency of these storms means it takes longer for stable ice cover to become established. As a result, sea ice doesn’t spread to the extent that the cold winter temperature normally would allow it to, leaving more ocean water open longer to release heat energy.

The Conversation is a creative commons site where the free flow of information is not restricted to the public but is meant to be shared.

Atmospheric rivers affect sea ice melting in two primary ways. More precipitation is falling as rain. But a larger influence on ice loss involves water vapor in the atmosphere. As water vapor turns into rainfall, the process releases a lot of heat, which warms the atmosphere. Water vapor also has a greenhouse effect that prevents heat from escaping into space. Together with the effect of clouds, they make the atmosphere much warmer than the sea ice. Scientists have known for years that heat from strong moisture transports could melt sea ice, but no one knew to what extent. That’s because it’s nearly impossible to install instruments on wild ice to conduct long-term energy exchange observation. We looked at it in a different way. We were able to establish a statistical linkage between the amount of ice loss and the average count of atmospheric rivers that arrived. In the Barents-Kara Seas and central Arctic, the Arctic quadrant with the most atmospheric river activity, we found that about 34% of the ice decline from 1979 to 2021 can be attributed to the increased frequency of atmospheric rivers.

Zhang suggested that by mid-century, every region in the Arctic will see an increase in Atmospheric Rivers caused by "extratropical cyclones that form over the oceans."

He writes about what this will mean for humans. Unfortunately, he lists as a benefit the exploitation by our collective suicide pact the exploitation and shipping of oil and liquid natural gas methane.

Of course, atmospheric rivers are also accompanied by strong wind, which can mean more dangerous wind storms for shipping and erosion for coastal areas. For some wildlife, the effects would be a disaster. Polar bears, for example, rely on sea ice to hunt seals. Loss of sea ice also contributes to climate change. Sea ice reflects incoming energy back into space. Without it, the dark oceans absorb more than 90% of that energy, which causes the oceans to heat up, with wide implications. According to the latest global assessment published by the Intergovernmental Panel on Climate Change, the Arctic could be almost entirely ice-free in summer by the middle of this century. That means thin, fragile ice across almost the entire region in early winter that would be susceptible to increasing storms.

For consideration, Zhang argues that the IPCC reports project the blue ocean event by mid-century. The IPCC is conservative due to some political and fossil fuel industry input. So take the year 2050 with a grain of salt. Climate change is accelerating, and scientists recognize that fact, maybe not publicly but privately.

[END]
---
[1] Url: https://www.dailykos.com/stories/2023/3/7/2156691/-Atmospheric-rivers-are-more-often-hitting-the-Arctic-and-melting-its-sea-ice

Published and (C) by Daily Kos
Content appears here under this condition or license: Site content may be used for any purpose without permission unless otherwise specified.

via Magical.Fish Gopher News Feeds:
gopher://magical.fish/1/feeds/news/dailykos/

You are viewing proxied material from magical.fish. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.